Merge lp:~chad.smith/landscape-client-charm/add-apt-repository-retries into lp:landscape-client-charm

[Chad Smith]

Sync charmhelpers for add_source retries to avoid hook errors on network timeouts. Because of charmhelpers sync fetch._run_apt_command moved to fetch.ubuntu._run_apt_command and fetch has new dependency on osplatform

We just added retries to the fetch.add_source function from in Charm helpers per https://code.launchpad.net/~chad.smith/charm-helpers/retry-add-apt-repository/+merge/318951

This branch only syncs latest charmhelpers per "make sync"

[🤖 Landscape Builder (landscape-builder)]

review: Abstain (executing tests)

[🤖 Landscape Builder (landscape-builder)]

Command: make ci-test
Result: Success
Revno: 64
Branch: lp:~chad.smith/landscape-client-charm/add-apt-repository-retries
Jenkins: https://ci.lscape.net/job/latch-test-trusty/747/

review: Approve (test results)

[Eric Snow (ericsnowcurrently)]

review: Approve

[lp:~chad.smith/landscape-client-charm/add-apt-repository-retries]

65. By Chad Smith on 2017-03-03

add charmhelpers.osplatform dependency and resync

[🤖 Landscape Builder (landscape-builder)]

review: Abstain (executing tests)

[🤖 Landscape Builder (landscape-builder)]

Command: make ci-test
Result: Success
Revno: 65
Branch: lp:~chad.smith/landscape-client-charm/add-apt-repository-retries
Jenkins: https://ci.lscape.net/job/latch-test-trusty/748/

review: Approve (test results)

[lp:~chad.smith/landscape-client-charm/add-apt-repository-retries]

66. By Chad Smith on 2017-03-03

import has moved in latest charmhelpers out to fetch.ubuntu

[🤖 Landscape Builder (landscape-builder)]

review: Abstain (executing tests)

[🤖 Landscape Builder (landscape-builder)]

Command: make ci-test
Result: Success
Revno: 66
Branch: lp:~chad.smith/landscape-client-charm/add-apt-repository-retries
Jenkins: https://ci.lscape.net/job/latch-test-trusty/749/

review: Approve (test results)

=== modified file 'charm-helpers-sync.yaml'
--- charm-helpers-sync.yaml	2014-05-11 12:16:14 +0000
+++ charm-helpers-sync.yaml	2017-03-03 23:04:07 +0000
@@ -3,6 +3,7 @@
 include:
     - core
     - fetch
+    - osplatform
 #    - contrib.storage.linux:
 #        - utils
 #    - payload.execd

=== modified file 'hooks/charmhelpers/__init__.py'
--- hooks/charmhelpers/__init__.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/__init__.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # Bootstrap charm-helpers, installing its dependencies if necessary using
 # only standard libraries.

=== modified file 'hooks/charmhelpers/core/__init__.py'
--- hooks/charmhelpers/core/__init__.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/__init__.py	2017-03-03 23:04:07 +0000
@@ -1,15 +1,13 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.

=== modified file 'hooks/charmhelpers/core/decorators.py'
--- hooks/charmhelpers/core/decorators.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/decorators.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 #
 # Copyright 2014 Canonical Ltd.

=== added file 'hooks/charmhelpers/core/files.py'
--- hooks/charmhelpers/core/files.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/files.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Copyright 2014-2015 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+__author__ = 'Jorge Niedbalski <[e-mail]>'
+
+import os
+import subprocess
+
+
+def sed(filename, before, after, flags='g'):
+    """
+    Search and replaces the given pattern on filename.
+
+    :param filename: relative or absolute file path.
+    :param before: expression to be replaced (see 'man sed')
+    :param after: expression to replace with (see 'man sed')
+    :param flags: sed-compatible regex flags in example, to make
+    the  search and replace case insensitive, specify ``flags="i"``.
+    The ``g`` flag is always specified regardless, so you do not
+    need to remember to include it when overriding this parameter.
+    :returns: If the sed command exit code was zero then return,
+    otherwise raise CalledProcessError.
+    """
+    expression = r's/{0}/{1}/{2}'.format(before,
+                                         after, flags)
+
+    return subprocess.check_call(["sed", "-i", "-r", "-e",
+                                  expression,
+                                  os.path.expanduser(filename)])

=== modified file 'hooks/charmhelpers/core/fstab.py'
--- hooks/charmhelpers/core/fstab.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/fstab.py	2017-03-03 23:04:07 +0000
@@ -3,19 +3,17 @@
 
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import io
 import os

=== modified file 'hooks/charmhelpers/core/hookenv.py'
--- hooks/charmhelpers/core/hookenv.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/hookenv.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 "Interactions with the Juju environment"
 # Copyright 2013 Canonical Ltd.
@@ -21,7 +19,10 @@
 #  Charm Helpers Developers <[e-mail]>
 
 from __future__ import print_function
+import copy
+from distutils.version import LooseVersion
 from functools import wraps
+import glob
 import os
 import json
 import yaml
@@ -71,6 +72,7 @@
         res = func(*args, **kwargs)
         cache[key] = res
         return res
+    wrapper._wrapped = func
     return wrapper
 
 
@@ -170,9 +172,19 @@
     return os.environ.get('JUJU_RELATION', None)
 
 
-def relation_id():
-    """The relation ID for the current relation hook"""
-    return os.environ.get('JUJU_RELATION_ID', None)
+@cached
+def relation_id(relation_name=None, service_or_unit=None):
+    """The relation ID for the current or a specified relation"""
+    if not relation_name and not service_or_unit:
+        return os.environ.get('JUJU_RELATION_ID', None)
+    elif relation_name and service_or_unit:
+        service_name = service_or_unit.split('/')[0]
+        for relid in relation_ids(relation_name):
+            remote_service = remote_service_name(relid)
+            if remote_service == service_name:
+                return relid
+    else:
+        raise ValueError('Must specify neither or both of relation_name and service_or_unit')
 
 
 def local_unit():
@@ -190,9 +202,20 @@
     return local_unit().split('/')[0]
 
 
+@cached
+def remote_service_name(relid=None):
+    """The remote service name for a given relation-id (or the current relation)"""
+    if relid is None:
+        unit = remote_unit()
+    else:
+        units = related_units(relid)
+        unit = units[0] if units else None
+    return unit.split('/')[0] if unit else None
+
+
 def hook_name():
     """The name of the currently executing hook"""
-    return os.path.basename(sys.argv[0])
+    return os.environ.get('JUJU_HOOK_NAME', os.path.basename(sys.argv[0]))
 
 
 class Config(dict):
@@ -242,29 +265,7 @@
         self.path = os.path.join(charm_dir(), Config.CONFIG_FILE_NAME)
         if os.path.exists(self.path):
             self.load_previous()
-
-    def __getitem__(self, key):
-        """For regular dict lookups, check the current juju config first,
-        then the previous (saved) copy. This ensures that user-saved values
-        will be returned by a dict lookup.
-
-        """
-        try:
-            return dict.__getitem__(self, key)
-        except KeyError:
-            return (self._prev_dict or {})[key]
-
-    def get(self, key, default=None):
-        try:
-            return self[key]
-        except KeyError:
-            return default
-
-    def keys(self):
-        prev_keys = []
-        if self._prev_dict is not None:
-            prev_keys = self._prev_dict.keys()
-        return list(set(prev_keys + list(dict.keys(self))))
+        atexit(self._implicit_save)
 
     def load_previous(self, path=None):
         """Load previous copy of config from disk.
@@ -283,6 +284,9 @@
         self.path = path or self.path
         with open(self.path) as f:
             self._prev_dict = json.load(f)
+        for k, v in copy.deepcopy(self._prev_dict).items():
+            if k not in self:
+                self[k] = v
 
     def changed(self, key):
         """Return True if the current value for this key is different from
@@ -314,13 +318,13 @@
         instance.
 
         """
-        if self._prev_dict:
-            for k, v in six.iteritems(self._prev_dict):
-                if k not in self:
-                    self[k] = v
         with open(self.path, 'w') as f:
             json.dump(self, f)
 
+    def _implicit_save(self):
+        if self.implicit_save:
+            self.save()
+
 
 @cached
 def config(scope=None):
@@ -328,6 +332,8 @@
     config_cmd_line = ['config-get']
     if scope is not None:
         config_cmd_line.append(scope)
+    else:
+        config_cmd_line.append('--all')
     config_cmd_line.append('--format=json')
     try:
         config_data = json.loads(
@@ -364,11 +370,16 @@
     relation_settings = relation_settings if relation_settings else {}
     relation_cmd_line = ['relation-set']
     accepts_file = "--file" in subprocess.check_output(
-        relation_cmd_line + ["--help"])
+        relation_cmd_line + ["--help"], universal_newlines=True)
     if relation_id is not None:
         relation_cmd_line.extend(('-r', relation_id))
     settings = relation_settings.copy()
     settings.update(kwargs)
+    for key, value in settings.items():
+        # Force value to be a string: it always should, but some call
+        # sites pass in things like dicts or numbers.
+        if value is not None:
+            settings[key] = "{}".format(value)
     if accepts_file:
         # --file was introduced in Juju 1.23.2. Use it by default if
         # available, since otherwise we'll break if the relation data is
@@ -480,6 +491,76 @@
 
 
 @cached
+def peer_relation_id():
+    '''Get the peers relation id if a peers relation has been joined, else None.'''
+    md = metadata()
+    section = md.get('peers')
+    if section:
+        for key in section:
+            relids = relation_ids(key)
+            if relids:
+                return relids[0]
+    return None
+
+
+@cached
+def relation_to_interface(relation_name):
+    """
+    Given the name of a relation, return the interface that relation uses.
+
+    :returns: The interface name, or ``None``.
+    """
+    return relation_to_role_and_interface(relation_name)[1]
+
+
+@cached
+def relation_to_role_and_interface(relation_name):
+    """
+    Given the name of a relation, return the role and the name of the interface
+    that relation uses (where role is one of ``provides``, ``requires``, or ``peers``).
+
+    :returns: A tuple containing ``(role, interface)``, or ``(None, None)``.
+    """
+    _metadata = metadata()
+    for role in ('provides', 'requires', 'peers'):
+        interface = _metadata.get(role, {}).get(relation_name, {}).get('interface')
+        if interface:
+            return role, interface
+    return None, None
+
+
+@cached
+def role_and_interface_to_relations(role, interface_name):
+    """
+    Given a role and interface name, return a list of relation names for the
+    current charm that use that interface under that role (where role is one
+    of ``provides``, ``requires``, or ``peers``).
+
+    :returns: A list of relation names.
+    """
+    _metadata = metadata()
+    results = []
+    for relation_name, relation in _metadata.get(role, {}).items():
+        if relation['interface'] == interface_name:
+            results.append(relation_name)
+    return results
+
+
+@cached
+def interface_to_relations(interface_name):
+    """
+    Given an interface, return a list of relation names for the current
+    charm that use that interface.
+
+    :returns: A list of relation names.
+    """
+    results = []
+    for role in ('provides', 'requires', 'peers'):
+        results.extend(role_and_interface_to_relations(role, interface_name))
+    return results
+
+
+@cached
 def charm_name():
     """Get the name of the current charm as is specified on metadata.yaml"""
     return metadata().get('name')
@@ -535,6 +616,20 @@
     subprocess.check_call(_args)
 
 
+def open_ports(start, end, protocol="TCP"):
+    """Opens a range of service network ports"""
+    _args = ['open-port']
+    _args.append('{}-{}/{}'.format(start, end, protocol))
+    subprocess.check_call(_args)
+
+
+def close_ports(start, end, protocol="TCP"):
+    """Close a range of service network ports"""
+    _args = ['close-port']
+    _args.append('{}-{}/{}'.format(start, end, protocol))
+    subprocess.check_call(_args)
+
+
 @cached
 def unit_get(attribute):
     """Get the unit ID for the remote unit"""
@@ -555,6 +650,38 @@
     return unit_get('private-address')
 
 
+@cached
+def storage_get(attribute=None, storage_id=None):
+    """Get storage attributes"""
+    _args = ['storage-get', '--format=json']
+    if storage_id:
+        _args.extend(('-s', storage_id))
+    if attribute:
+        _args.append(attribute)
+    try:
+        return json.loads(subprocess.check_output(_args).decode('UTF-8'))
+    except ValueError:
+        return None
+
+
+@cached
+def storage_list(storage_name=None):
+    """List the storage IDs for the unit"""
+    _args = ['storage-list', '--format=json']
+    if storage_name:
+        _args.append(storage_name)
+    try:
+        return json.loads(subprocess.check_output(_args).decode('UTF-8'))
+    except ValueError:
+        return None
+    except OSError as e:
+        import errno
+        if e.errno == errno.ENOENT:
+            # storage-list does not exist
+            return []
+        raise
+
+
 class UnregisteredHookError(Exception):
     """Raised when an undefined hook is called"""
     pass
@@ -582,10 +709,14 @@
             hooks.execute(sys.argv)
     """
 
-    def __init__(self, config_save=True):
+    def __init__(self, config_save=None):
         super(Hooks, self).__init__()
         self._hooks = {}
-        self._config_save = config_save
+
+        # For unknown reasons, we allow the Hooks constructor to override
+        # config().implicit_save.
+        if config_save is not None:
+            config().implicit_save = config_save
 
     def register(self, name, function):
         """Register a hook"""
@@ -593,13 +724,16 @@
 
     def execute(self, args):
         """Execute a registered hook based on args[0]"""
+        _run_atstart()
         hook_name = os.path.basename(args[0])
         if hook_name in self._hooks:
-            self._hooks[hook_name]()
-            if self._config_save:
-                cfg = config()
-                if cfg.implicit_save:
-                    cfg.save()
+            try:
+                self._hooks[hook_name]()
+            except SystemExit as x:
+                if x.code is None or x.code == 0:
+                    _run_atexit()
+                raise
+            _run_atexit()
         else:
             raise UnregisteredHookError(hook_name)
 
@@ -648,6 +782,21 @@
     subprocess.check_call(['action-fail', message])
 
 
+def action_name():
+    """Get the name of the currently executing action."""
+    return os.environ.get('JUJU_ACTION_NAME')
+
+
+def action_uuid():
+    """Get the UUID of the currently executing action."""
+    return os.environ.get('JUJU_ACTION_UUID')
+
+
+def action_tag():
+    """Get the tag for the currently executing action."""
+    return os.environ.get('JUJU_ACTION_TAG')
+
+
 def status_set(workload_state, message):
     """Set the workload state with a message
 
@@ -677,25 +826,28 @@
 
 
 def status_get():
-    """Retrieve the previously set juju workload state
-
-    If the status-set command is not found then assume this is juju < 1.23 and
-    return 'unknown'
+    """Retrieve the previously set juju workload state and message
+
+    If the status-get command is not found then assume this is juju < 1.23 and
+    return 'unknown', ""
+
     """
-    cmd = ['status-get']
+    cmd = ['status-get', "--format=json", "--include-data"]
     try:
-        raw_status = subprocess.check_output(cmd, universal_newlines=True)
-        status = raw_status.rstrip()
-        return status
+        raw_status = subprocess.check_output(cmd)
     except OSError as e:
         if e.errno == errno.ENOENT:
-            return 'unknown'
+            return ('unknown', "")
         else:
             raise
+    else:
+        status = json.loads(raw_status.decode("UTF-8"))
+        return (status["status"], status["message"])
 
 
 def translate_exc(from_exc, to_exc):
     def inner_translate_exc1(f):
+        @wraps(f)
         def inner_translate_exc2(*args, **kwargs):
             try:
                 return f(*args, **kwargs)
@@ -707,6 +859,20 @@
     return inner_translate_exc1
 
 
+def application_version_set(version):
+    """Charm authors may trigger this command from any hook to output what
+    version of the application is running. This could be a package version,
+    for instance postgres version 9.5. It could also be a build number or
+    version control revision identifier, for instance git sha 6fb7ba68. """
+
+    cmd = ['application-version-set']
+    cmd.append(version)
+    try:
+        subprocess.check_call(cmd)
+    except OSError:
+        log("Application Version: {}".format(version))
+
+
 @translate_exc(from_exc=OSError, to_exc=NotImplementedError)
 def is_leader():
     """Does the current unit hold the juju leadership
@@ -727,13 +893,176 @@
 @translate_exc(from_exc=OSError, to_exc=NotImplementedError)
 def leader_set(settings=None, **kwargs):
     """Juju leader set value(s)"""
-    log("Juju leader-set '%s'" % (settings), level=DEBUG)
+    # Don't log secrets.
+    # log("Juju leader-set '%s'" % (settings), level=DEBUG)
     cmd = ['leader-set']
     settings = settings or {}
     settings.update(kwargs)
-    for k, v in settings.iteritems():
+    for k, v in settings.items():
         if v is None:
             cmd.append('{}='.format(k))
         else:
             cmd.append('{}={}'.format(k, v))
     subprocess.check_call(cmd)
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def payload_register(ptype, klass, pid):
+    """ is used while a hook is running to let Juju know that a
+        payload has been started."""
+    cmd = ['payload-register']
+    for x in [ptype, klass, pid]:
+        cmd.append(x)
+    subprocess.check_call(cmd)
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def payload_unregister(klass, pid):
+    """ is used while a hook is running to let Juju know
+    that a payload has been manually stopped. The <class> and <id> provided
+    must match a payload that has been previously registered with juju using
+    payload-register."""
+    cmd = ['payload-unregister']
+    for x in [klass, pid]:
+        cmd.append(x)
+    subprocess.check_call(cmd)
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def payload_status_set(klass, pid, status):
+    """is used to update the current status of a registered payload.
+    The <class> and <id> provided must match a payload that has been previously
+    registered with juju using payload-register. The <status> must be one of the
+    follow: starting, started, stopping, stopped"""
+    cmd = ['payload-status-set']
+    for x in [klass, pid, status]:
+        cmd.append(x)
+    subprocess.check_call(cmd)
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def resource_get(name):
+    """used to fetch the resource path of the given name.
+
+    <name> must match a name of defined resource in metadata.yaml
+
+    returns either a path or False if resource not available
+    """
+    if not name:
+        return False
+
+    cmd = ['resource-get', name]
+    try:
+        return subprocess.check_output(cmd).decode('UTF-8')
+    except subprocess.CalledProcessError:
+        return False
+
+
+@cached
+def juju_version():
+    """Full version string (eg. '1.23.3.1-trusty-amd64')"""
+    # Per https://bugs.launchpad.net/juju-core/+bug/1455368/comments/1
+    jujud = glob.glob('/var/lib/juju/tools/machine-*/jujud')[0]
+    return subprocess.check_output([jujud, 'version'],
+                                   universal_newlines=True).strip()
+
+
+@cached
+def has_juju_version(minimum_version):
+    """Return True if the Juju version is at least the provided version"""
+    return LooseVersion(juju_version()) >= LooseVersion(minimum_version)
+
+
+_atexit = []
+_atstart = []
+
+
+def atstart(callback, *args, **kwargs):
+    '''Schedule a callback to run before the main hook.
+
+    Callbacks are run in the order they were added.
+
+    This is useful for modules and classes to perform initialization
+    and inject behavior. In particular:
+
+        - Run common code before all of your hooks, such as logging
+          the hook name or interesting relation data.
+        - Defer object or module initialization that requires a hook
+          context until we know there actually is a hook context,
+          making testing easier.
+        - Rather than requiring charm authors to include boilerplate to
+          invoke your helper's behavior, have it run automatically if
+          your object is instantiated or module imported.
+
+    This is not at all useful after your hook framework as been launched.
+    '''
+    global _atstart
+    _atstart.append((callback, args, kwargs))
+
+
+def atexit(callback, *args, **kwargs):
+    '''Schedule a callback to run on successful hook completion.
+
+    Callbacks are run in the reverse order that they were added.'''
+    _atexit.append((callback, args, kwargs))
+
+
+def _run_atstart():
+    '''Hook frameworks must invoke this before running the main hook body.'''
+    global _atstart
+    for callback, args, kwargs in _atstart:
+        callback(*args, **kwargs)
+    del _atstart[:]
+
+
+def _run_atexit():
+    '''Hook frameworks must invoke this after the main hook body has
+    successfully completed. Do not invoke it if the hook fails.'''
+    global _atexit
+    for callback, args, kwargs in reversed(_atexit):
+        callback(*args, **kwargs)
+    del _atexit[:]
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def network_get_primary_address(binding):
+    '''
+    Retrieve the primary network address for a named binding
+
+    :param binding: string. The name of a relation of extra-binding
+    :return: string. The primary IP address for the named binding
+    :raise: NotImplementedError if run on Juju < 2.0
+    '''
+    cmd = ['network-get', '--primary-address', binding]
+    return subprocess.check_output(cmd).decode('UTF-8').strip()
+
+
+def add_metric(*args, **kwargs):
+    """Add metric values. Values may be expressed with keyword arguments. For
+    metric names containing dashes, these may be expressed as one or more
+    'key=value' positional arguments. May only be called from the collect-metrics
+    hook."""
+    _args = ['add-metric']
+    _kvpairs = []
+    _kvpairs.extend(args)
+    _kvpairs.extend(['{}={}'.format(k, v) for k, v in kwargs.items()])
+    _args.extend(sorted(_kvpairs))
+    try:
+        subprocess.check_call(_args)
+        return
+    except EnvironmentError as e:
+        if e.errno != errno.ENOENT:
+            raise
+    log_message = 'add-metric failed: {}'.format(' '.join(_kvpairs))
+    log(log_message, level='INFO')
+
+
+def meter_status():
+    """Get the meter status, if running in the meter-status-changed hook."""
+    return os.environ.get('JUJU_METER_STATUS')
+
+
+def meter_info():
+    """Get the meter status information, if running in the meter-status-changed
+    hook."""
+    return os.environ.get('JUJU_METER_INFO')

=== modified file 'hooks/charmhelpers/core/host.py'
--- hooks/charmhelpers/core/host.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/host.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 """Tools for working with the host system"""
 # Copyright 2012 Canonical Ltd.
@@ -24,85 +22,324 @@
 import os
 import re
 import pwd
+import glob
 import grp
 import random
 import string
 import subprocess
 import hashlib
+import functools
+import itertools
+import six
+
 from contextlib import contextmanager
 from collections import OrderedDict
-
-import six
-
 from .hookenv import log
 from .fstab import Fstab
-
-
-def service_start(service_name):
-    """Start a system service"""
-    return service('start', service_name)
-
-
-def service_stop(service_name):
-    """Stop a system service"""
-    return service('stop', service_name)
-
-
-def service_restart(service_name):
-    """Restart a system service"""
+from charmhelpers.osplatform import get_platform
+
+__platform__ = get_platform()
+if __platform__ == "ubuntu":
+    from charmhelpers.core.host_factory.ubuntu import (
+        service_available,
+        add_new_group,
+        lsb_release,
+        cmp_pkgrevno,
+    )  # flake8: noqa -- ignore F401 for this import
+elif __platform__ == "centos":
+    from charmhelpers.core.host_factory.centos import (
+        service_available,
+        add_new_group,
+        lsb_release,
+        cmp_pkgrevno,
+    )  # flake8: noqa -- ignore F401 for this import
+
+UPDATEDB_PATH = '/etc/updatedb.conf'
+
+def service_start(service_name, **kwargs):
+    """Start a system service.
+
+    The specified service name is managed via the system level init system.
+    Some init systems (e.g. upstart) require that additional arguments be
+    provided in order to directly control service instances whereas other init
+    systems allow for addressing instances of a service directly by name (e.g.
+    systemd).
+
+    The kwargs allow for the additional parameters to be passed to underlying
+    init systems for those systems which require/allow for them. For example,
+    the ceph-osd upstart script requires the id parameter to be passed along
+    in order to identify which running daemon should be reloaded. The follow-
+    ing example stops the ceph-osd service for instance id=4:
+
+    service_stop('ceph-osd', id=4)
+
+    :param service_name: the name of the service to stop
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the init system's commandline. kwargs
+                     are ignored for systemd enabled systems.
+    """
+    return service('start', service_name, **kwargs)
+
+
+def service_stop(service_name, **kwargs):
+    """Stop a system service.
+
+    The specified service name is managed via the system level init system.
+    Some init systems (e.g. upstart) require that additional arguments be
+    provided in order to directly control service instances whereas other init
+    systems allow for addressing instances of a service directly by name (e.g.
+    systemd).
+
+    The kwargs allow for the additional parameters to be passed to underlying
+    init systems for those systems which require/allow for them. For example,
+    the ceph-osd upstart script requires the id parameter to be passed along
+    in order to identify which running daemon should be reloaded. The follow-
+    ing example stops the ceph-osd service for instance id=4:
+
+    service_stop('ceph-osd', id=4)
+
+    :param service_name: the name of the service to stop
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the init system's commandline. kwargs
+                     are ignored for systemd enabled systems.
+    """
+    return service('stop', service_name, **kwargs)
+
+
+def service_restart(service_name, **kwargs):
+    """Restart a system service.
+
+    The specified service name is managed via the system level init system.
+    Some init systems (e.g. upstart) require that additional arguments be
+    provided in order to directly control service instances whereas other init
+    systems allow for addressing instances of a service directly by name (e.g.
+    systemd).
+
+    The kwargs allow for the additional parameters to be passed to underlying
+    init systems for those systems which require/allow for them. For example,
+    the ceph-osd upstart script requires the id parameter to be passed along
+    in order to identify which running daemon should be restarted. The follow-
+    ing example restarts the ceph-osd service for instance id=4:
+
+    service_restart('ceph-osd', id=4)
+
+    :param service_name: the name of the service to restart
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the  init system's commandline. kwargs
+                     are ignored for init systems not allowing additional
+                     parameters via the commandline (systemd).
+    """
     return service('restart', service_name)
 
 
-def service_reload(service_name, restart_on_failure=False):
+def service_reload(service_name, restart_on_failure=False, **kwargs):
     """Reload a system service, optionally falling back to restart if
-    reload fails"""
-    service_result = service('reload', service_name)
+    reload fails.
+
+    The specified service name is managed via the system level init system.
+    Some init systems (e.g. upstart) require that additional arguments be
+    provided in order to directly control service instances whereas other init
+    systems allow for addressing instances of a service directly by name (e.g.
+    systemd).
+
+    The kwargs allow for the additional parameters to be passed to underlying
+    init systems for those systems which require/allow for them. For example,
+    the ceph-osd upstart script requires the id parameter to be passed along
+    in order to identify which running daemon should be reloaded. The follow-
+    ing example restarts the ceph-osd service for instance id=4:
+
+    service_reload('ceph-osd', id=4)
+
+    :param service_name: the name of the service to reload
+    :param restart_on_failure: boolean indicating whether to fallback to a
+                               restart if the reload fails.
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the  init system's commandline. kwargs
+                     are ignored for init systems not allowing additional
+                     parameters via the commandline (systemd).
+    """
+    service_result = service('reload', service_name, **kwargs)
     if not service_result and restart_on_failure:
-        service_result = service('restart', service_name)
+        service_result = service('restart', service_name, **kwargs)
     return service_result
 
 
-def service(action, service_name):
-    """Control a system service"""
-    cmd = ['service', service_name, action]
+def service_pause(service_name, init_dir="/etc/init", initd_dir="/etc/init.d",
+                  **kwargs):
+    """Pause a system service.
+
+    Stop it, and prevent it from starting again at boot.
+
+    :param service_name: the name of the service to pause
+    :param init_dir: path to the upstart init directory
+    :param initd_dir: path to the sysv init directory
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the init system's commandline. kwargs
+                     are ignored for init systems which do not support
+                     key=value arguments via the commandline.
+    """
+    stopped = True
+    if service_running(service_name, **kwargs):
+        stopped = service_stop(service_name, **kwargs)
+    upstart_file = os.path.join(init_dir, "{}.conf".format(service_name))
+    sysv_file = os.path.join(initd_dir, service_name)
+    if init_is_systemd():
+        service('disable', service_name)
+    elif os.path.exists(upstart_file):
+        override_path = os.path.join(
+            init_dir, '{}.override'.format(service_name))
+        with open(override_path, 'w') as fh:
+            fh.write("manual\n")
+    elif os.path.exists(sysv_file):
+        subprocess.check_call(["update-rc.d", service_name, "disable"])
+    else:
+        raise ValueError(
+            "Unable to detect {0} as SystemD, Upstart {1} or"
+            " SysV {2}".format(
+                service_name, upstart_file, sysv_file))
+    return stopped
+
+
+def service_resume(service_name, init_dir="/etc/init",
+                   initd_dir="/etc/init.d", **kwargs):
+    """Resume a system service.
+
+    Reenable starting again at boot. Start the service.
+
+    :param service_name: the name of the service to resume
+    :param init_dir: the path to the init dir
+    :param initd dir: the path to the initd dir
+    :param **kwargs: additional parameters to pass to the init system when
+                     managing services. These will be passed as key=value
+                     parameters to the init system's commandline. kwargs
+                     are ignored for systemd enabled systems.
+    """
+    upstart_file = os.path.join(init_dir, "{}.conf".format(service_name))
+    sysv_file = os.path.join(initd_dir, service_name)
+    if init_is_systemd():
+        service('enable', service_name)
+    elif os.path.exists(upstart_file):
+        override_path = os.path.join(
+            init_dir, '{}.override'.format(service_name))
+        if os.path.exists(override_path):
+            os.unlink(override_path)
+    elif os.path.exists(sysv_file):
+        subprocess.check_call(["update-rc.d", service_name, "enable"])
+    else:
+        raise ValueError(
+            "Unable to detect {0} as SystemD, Upstart {1} or"
+            " SysV {2}".format(
+                service_name, upstart_file, sysv_file))
+    started = service_running(service_name, **kwargs)
+
+    if not started:
+        started = service_start(service_name, **kwargs)
+    return started
+
+
+def service(action, service_name, **kwargs):
+    """Control a system service.
+
+    :param action: the action to take on the service
+    :param service_name: the name of the service to perform th action on
+    :param **kwargs: additional params to be passed to the service command in
+                    the form of key=value.
+    """
+    if init_is_systemd():
+        cmd = ['systemctl', action, service_name]
+    else:
+        cmd = ['service', service_name, action]
+        for key, value in six.iteritems(kwargs):
+            parameter = '%s=%s' % (key, value)
+            cmd.append(parameter)
     return subprocess.call(cmd) == 0
 
 
-def service_running(service):
-    """Determine whether a system service is running"""
-    try:
-        output = subprocess.check_output(
-            ['service', service, 'status'],
-            stderr=subprocess.STDOUT).decode('UTF-8')
-    except subprocess.CalledProcessError:
+_UPSTART_CONF = "/etc/init/{}.conf"
+_INIT_D_CONF = "/etc/init.d/{}"
+
+
+def service_running(service_name, **kwargs):
+    """Determine whether a system service is running.
+
+    :param service_name: the name of the service
+    :param **kwargs: additional args to pass to the service command. This is
+                     used to pass additional key=value arguments to the
+                     service command line for managing specific instance
+                     units (e.g. service ceph-osd status id=2). The kwargs
+                     are ignored in systemd services.
+    """
+    if init_is_systemd():
+        return service('is-active', service_name)
+    else:
+        if os.path.exists(_UPSTART_CONF.format(service_name)):
+            try:
+                cmd = ['status', service_name]
+                for key, value in six.iteritems(kwargs):
+                    parameter = '%s=%s' % (key, value)
+                    cmd.append(parameter)
+                output = subprocess.check_output(cmd,
+                    stderr=subprocess.STDOUT).decode('UTF-8')
+            except subprocess.CalledProcessError:
+                return False
+            else:
+                # This works for upstart scripts where the 'service' command
+                # returns a consistent string to represent running
+                # 'start/running'
+                if ("start/running" in output or
+                        "is running" in output or
+                        "up and running" in output):
+                    return True
+        elif os.path.exists(_INIT_D_CONF.format(service_name)):
+            # Check System V scripts init script return codes
+            return service('status', service_name)
         return False
-    else:
-        if ("start/running" in output or "is running" in output):
-            return True
-        else:
-            return False
-
-
-def service_available(service_name):
-    """Determine whether a system service is available"""
-    try:
-        subprocess.check_output(
-            ['service', service_name, 'status'],
-            stderr=subprocess.STDOUT).decode('UTF-8')
-    except subprocess.CalledProcessError as e:
-        return b'unrecognized service' not in e.output
-    else:
-        return True
-
-
-def adduser(username, password=None, shell='/bin/bash', system_user=False):
-    """Add a user to the system"""
+
+
+SYSTEMD_SYSTEM = '/run/systemd/system'
+
+
+def init_is_systemd():
+    """Return True if the host system uses systemd, False otherwise."""
+    return os.path.isdir(SYSTEMD_SYSTEM)
+
+
+def adduser(username, password=None, shell='/bin/bash',
+            system_user=False, primary_group=None,
+            secondary_groups=None, uid=None, home_dir=None):
+    """Add a user to the system.
+
+    Will log but otherwise succeed if the user already exists.
+
+    :param str username: Username to create
+    :param str password: Password for user; if ``None``, create a system user
+    :param str shell: The default shell for the user
+    :param bool system_user: Whether to create a login or system user
+    :param str primary_group: Primary group for user; defaults to username
+    :param list secondary_groups: Optional list of additional groups
+    :param int uid: UID for user being created
+    :param str home_dir: Home directory for user
+
+    :returns: The password database entry struct, as returned by `pwd.getpwnam`
+    """
     try:
         user_info = pwd.getpwnam(username)
         log('user {0} already exists!'.format(username))
+        if uid:
+            user_info = pwd.getpwuid(int(uid))
+            log('user with uid {0} already exists!'.format(uid))
     except KeyError:
         log('creating user {0}'.format(username))
         cmd = ['useradd']
+        if uid:
+            cmd.extend(['--uid', str(uid)])
+        if home_dir:
+            cmd.extend(['--home', str(home_dir)])
         if system_user or password is None:
             cmd.append('--system')
         else:
@@ -111,52 +348,104 @@
                 '--shell', shell,
                 '--password', password,
             ])
+        if not primary_group:
+            try:
+                grp.getgrnam(username)
+                primary_group = username  # avoid "group exists" error
+            except KeyError:
+                pass
+        if primary_group:
+            cmd.extend(['-g', primary_group])
+        if secondary_groups:
+            cmd.extend(['-G', ','.join(secondary_groups)])
         cmd.append(username)
         subprocess.check_call(cmd)
         user_info = pwd.getpwnam(username)
     return user_info
 
 
-def add_group(group_name, system_group=False):
-    """Add a group to the system"""
+def user_exists(username):
+    """Check if a user exists"""
+    try:
+        pwd.getpwnam(username)
+        user_exists = True
+    except KeyError:
+        user_exists = False
+    return user_exists
+
+
+def uid_exists(uid):
+    """Check if a uid exists"""
+    try:
+        pwd.getpwuid(uid)
+        uid_exists = True
+    except KeyError:
+        uid_exists = False
+    return uid_exists
+
+
+def group_exists(groupname):
+    """Check if a group exists"""
+    try:
+        grp.getgrnam(groupname)
+        group_exists = True
+    except KeyError:
+        group_exists = False
+    return group_exists
+
+
+def gid_exists(gid):
+    """Check if a gid exists"""
+    try:
+        grp.getgrgid(gid)
+        gid_exists = True
+    except KeyError:
+        gid_exists = False
+    return gid_exists
+
+
+def add_group(group_name, system_group=False, gid=None):
+    """Add a group to the system
+
+    Will log but otherwise succeed if the group already exists.
+
+    :param str group_name: group to create
+    :param bool system_group: Create system group
+    :param int gid: GID for user being created
+
+    :returns: The password database entry struct, as returned by `grp.getgrnam`
+    """
     try:
         group_info = grp.getgrnam(group_name)
         log('group {0} already exists!'.format(group_name))
+        if gid:
+            group_info = grp.getgrgid(gid)
+            log('group with gid {0} already exists!'.format(gid))
     except KeyError:
         log('creating group {0}'.format(group_name))
-        cmd = ['addgroup']
-        if system_group:
-            cmd.append('--system')
-        else:
-            cmd.extend([
-                '--group',
-            ])
-        cmd.append(group_name)
-        subprocess.check_call(cmd)
+        add_new_group(group_name, system_group, gid)
         group_info = grp.getgrnam(group_name)
     return group_info
 
 
 def add_user_to_group(username, group):
     """Add a user to a group"""
-    cmd = [
-        'gpasswd', '-a',
-        username,
-        group
-    ]
+    cmd = ['gpasswd', '-a', username, group]
     log("Adding user {} to group {}".format(username, group))
     subprocess.check_call(cmd)
 
 
-def rsync(from_path, to_path, flags='-r', options=None):
+def rsync(from_path, to_path, flags='-r', options=None, timeout=None):
     """Replicate the contents of a path"""
     options = options or ['--delete', '--executability']
     cmd = ['/usr/bin/rsync', flags]
+    if timeout:
+        cmd = ['timeout', str(timeout)] + cmd
     cmd.extend(options)
     cmd.append(from_path)
     cmd.append(to_path)
     log(" ".join(cmd))
-    return subprocess.check_output(cmd).decode('UTF-8').strip()
+    return subprocess.check_output(cmd, stderr=subprocess.STDOUT).decode('UTF-8').strip()
 
 
 def symlink(source, destination):
@@ -202,14 +491,12 @@
 
 
 def fstab_remove(mp):
-    """Remove the given mountpoint entry from /etc/fstab
-    """
+    """Remove the given mountpoint entry from /etc/fstab"""
     return Fstab.remove_by_mountpoint(mp)
 
 
 def fstab_add(dev, mp, fs, options=None):
-    """Adds the given device entry to the /etc/fstab file
-    """
+    """Adds the given device entry to the /etc/fstab file"""
     return Fstab.add(dev, mp, fs, options=options)
 
 
@@ -253,9 +540,19 @@
     return system_mounts
 
 
+def fstab_mount(mountpoint):
+    """Mount filesystem using fstab"""
+    cmd_args = ['mount', mountpoint]
+    try:
+        subprocess.check_output(cmd_args)
+    except subprocess.CalledProcessError as e:
+        log('Error unmounting {}\n{}'.format(mountpoint, e.output))
+        return False
+    return True
+
+
 def file_hash(path, hash_type='md5'):
-    """
-    Generate a hash checksum of the contents of 'path' or None if not found.
+    """Generate a hash checksum of the contents of 'path' or None if not found.
 
     :param str hash_type: Any hash alrgorithm supported by :mod:`hashlib`,
                           such as md5, sha1, sha256, sha512, etc.
@@ -269,9 +566,22 @@
         return None
 
 
+def path_hash(path):
+    """Generate a hash checksum of all files matching 'path'. Standard
+    wildcards like '*' and '?' are supported, see documentation for the 'glob'
+    module for more information.
+
+    :return: dict: A { filename: hash } dictionary for all matched files.
+                   Empty if none found.
+    """
+    return {
+        filename: file_hash(filename)
+        for filename in glob.iglob(path)
+    }
+
+
 def check_hash(path, checksum, hash_type='md5'):
-    """
-    Validate a file using a cryptographic checksum.
+    """Validate a file using a cryptographic checksum.
 
     :param str checksum: Value of the checksum used to validate the file.
     :param str hash_type: Hash algorithm used to generate `checksum`.
@@ -286,54 +596,78 @@
 
 
 class ChecksumError(ValueError):
+    """A class derived from Value error to indicate the checksum failed."""
     pass
 
 
-def restart_on_change(restart_map, stopstart=False):
+def restart_on_change(restart_map, stopstart=False, restart_functions=None):
     """Restart services based on configuration files changing
 
     This function is used a decorator, for example::
 
         @restart_on_change({
             '/etc/ceph/ceph.conf': [ 'cinder-api', 'cinder-volume' ]
+            '/etc/apache/sites-enabled/*': [ 'apache2' ]
             })
-        def ceph_client_changed():
+        def config_changed():
             pass  # your code here
 
     In this example, the cinder-api and cinder-volume services
     would be restarted if /etc/ceph/ceph.conf is changed by the
-    ceph_client_changed function.
+    ceph_client_changed function. The apache2 service would be
+    restarted if any file matching the pattern got changed, created
+    or removed. Standard wildcards are supported, see documentation
+    for the 'glob' module for more information.
+
+    @param restart_map: {path_file_name: [service_name, ...]
+    @param stopstart: DEFAULT false; whether to stop, start OR restart
+    @param restart_functions: nonstandard functions to use to restart services
+                              {svc: func, ...}
+    @returns result from decorated function
     """
     def wrap(f):
+        @functools.wraps(f)
         def wrapped_f(*args, **kwargs):
-            checksums = {}
-            for path in restart_map:
-                checksums[path] = file_hash(path)
-            f(*args, **kwargs)
-            restarts = []
-            for path in restart_map:
-                if checksums[path] != file_hash(path):
-                    restarts += restart_map[path]
-            services_list = list(OrderedDict.fromkeys(restarts))
-            if not stopstart:
-                for service_name in services_list:
-                    service('restart', service_name)
-            else:
-                for action in ['stop', 'start']:
-                    for service_name in services_list:
-                        service(action, service_name)
+            return restart_on_change_helper(
+                (lambda: f(*args, **kwargs)), restart_map, stopstart,
+                restart_functions)
         return wrapped_f
     return wrap
 
 
-def lsb_release():
-    """Return /etc/lsb-release in a dict"""
-    d = {}
-    with open('/etc/lsb-release', 'r') as lsb:
-        for l in lsb:
-            k, v = l.split('=')
-            d[k.strip()] = v.strip()
-    return d
+def restart_on_change_helper(lambda_f, restart_map, stopstart=False,
+                             restart_functions=None):
+    """Helper function to perform the restart_on_change function.
+
+    This is provided for decorators to restart services if files described
+    in the restart_map have changed after an invocation of lambda_f().
+
+    @param lambda_f: function to call.
+    @param restart_map: {file: [service, ...]}
+    @param stopstart: whether to stop, start or restart a service
+    @param restart_functions: nonstandard functions to use to restart services
+                              {svc: func, ...}
+    @returns result of lambda_f()
+    """
+    if restart_functions is None:
+        restart_functions = {}
+    checksums = {path: path_hash(path) for path in restart_map}
+    r = lambda_f()
+    # create a list of lists of the services to restart
+    restarts = [restart_map[path]
+                for path in restart_map
+                if path_hash(path) != checksums[path]]
+    # create a flat list of ordered services without duplicates from lists
+    services_list = list(OrderedDict.fromkeys(itertools.chain(*restarts)))
+    if services_list:
+        actions = ('stop', 'start') if stopstart else ('restart',)
+        for service_name in services_list:
+            if service_name in restart_functions:
+                restart_functions[service_name](service_name)
+            else:
+                for action in actions:
+                    service(action, service_name)
+    return r
 
 
 def pwgen(length=None):
@@ -352,36 +686,92 @@
     return(''.join(random_chars))
 
 
-def list_nics(nic_type):
-    '''Return a list of nics of given type(s)'''
+def is_phy_iface(interface):
+    """Returns True if interface is not virtual, otherwise False."""
+    if interface:
+        sys_net = '/sys/class/net'
+        if os.path.isdir(sys_net):
+            for iface in glob.glob(os.path.join(sys_net, '*')):
+                if '/virtual/' in os.path.realpath(iface):
+                    continue
+
+                if interface == os.path.basename(iface):
+                    return True
+
+    return False
+
+
+def get_bond_master(interface):
+    """Returns bond master if interface is bond slave otherwise None.
+
+    NOTE: the provided interface is expected to be physical
+    """
+    if interface:
+        iface_path = '/sys/class/net/%s' % (interface)
+        if os.path.exists(iface_path):
+            if '/virtual/' in os.path.realpath(iface_path):
+                return None
+
+            master = os.path.join(iface_path, 'master')
+            if os.path.exists(master):
+                master = os.path.realpath(master)
+                # make sure it is a bond master
+                if os.path.exists(os.path.join(master, 'bonding')):
+                    return os.path.basename(master)
+
+    return None
+
+
+def list_nics(nic_type=None):
+    """Return a list of nics of given type(s)"""
     if isinstance(nic_type, six.string_types):
         int_types = [nic_type]
     else:
         int_types = nic_type
+
     interfaces = []
-    for int_type in int_types:
-        cmd = ['ip', 'addr', 'show', 'label', int_type + '*']
+    if nic_type:
+        for int_type in int_types:
+            cmd = ['ip', 'addr', 'show', 'label', int_type + '*']
+            ip_output = subprocess.check_output(cmd).decode('UTF-8')
+            ip_output = ip_output.split('\n')
+            ip_output = (line for line in ip_output if line)
+            for line in ip_output:
+                if line.split()[1].startswith(int_type):
+                    matched = re.search('.*: (' + int_type +
+                                        r'[0-9]+\.[0-9]+)@.*', line)
+                    if matched:
+                        iface = matched.groups()[0]
+                    else:
+                        iface = line.split()[1].replace(":", "")
+
+                    if iface not in interfaces:
+                        interfaces.append(iface)
+    else:
+        cmd = ['ip', 'a']
         ip_output = subprocess.check_output(cmd).decode('UTF-8').split('\n')
-        ip_output = (line for line in ip_output if line)
+        ip_output = (line.strip() for line in ip_output if line)
+
+        key = re.compile('^[0-9]+:\s+(.+):')
         for line in ip_output:
-            if line.split()[1].startswith(int_type):
-                matched = re.search('.*: (' + int_type + r'[0-9]+\.[0-9]+)@.*', line)
-                if matched:
-                    interface = matched.groups()[0]
-                else:
-                    interface = line.split()[1].replace(":", "")
-                interfaces.append(interface)
+            matched = re.search(key, line)
+            if matched:
+                iface = matched.group(1)
+                iface = iface.partition("@")[0]
+                if iface not in interfaces:
+                    interfaces.append(iface)
 
     return interfaces
 
 
 def set_nic_mtu(nic, mtu):
-    '''Set MTU on a network interface'''
+    """Set the Maximum Transmission Unit (MTU) on a network interface."""
     cmd = ['ip', 'link', 'set', nic, 'mtu', mtu]
     subprocess.check_call(cmd)
 
 
 def get_nic_mtu(nic):
+    """Return the Maximum Transmission Unit (MTU) for a network interface."""
     cmd = ['ip', 'addr', 'show', nic]
     ip_output = subprocess.check_output(cmd).decode('UTF-8').split('\n')
     mtu = ""
@@ -393,6 +783,7 @@
 
 
 def get_nic_hwaddr(nic):
+    """Return the Media Access Control (MAC) for a network interface."""
     cmd = ['ip', '-o', '-0', 'addr', 'show', nic]
     ip_output = subprocess.check_output(cmd).decode('UTF-8')
     hwaddr = ""
@@ -402,35 +793,31 @@
     return hwaddr
 
 
-def cmp_pkgrevno(package, revno, pkgcache=None):
-    '''Compare supplied revno with the revno of the installed package
-
-    *  1 => Installed revno is greater than supplied arg
-    *  0 => Installed revno is the same as supplied arg
-    * -1 => Installed revno is less than supplied arg
-
-    This function imports apt_cache function from charmhelpers.fetch if
-    the pkgcache argument is None. Be sure to add charmhelpers.fetch if
-    you call this function, or pass an apt_pkg.Cache() instance.
-    '''
-    import apt_pkg
-    if not pkgcache:
-        from charmhelpers.fetch import apt_cache
-        pkgcache = apt_cache()
-    pkg = pkgcache[package]
-    return apt_pkg.version_compare(pkg.current_ver.ver_str, revno)
-
-
 @contextmanager
-def chdir(d):
+def chdir(directory):
+    """Change the current working directory to a different directory for a code
+    block and return the previous directory after the block exits. Useful to
+    run commands from a specificed directory.
+
+    :param str directory: The directory path to change to for this context.
+    """
     cur = os.getcwd()
     try:
-        yield os.chdir(d)
+        yield os.chdir(directory)
     finally:
         os.chdir(cur)
 
 
-def chownr(path, owner, group, follow_links=True):
+def chownr(path, owner, group, follow_links=True, chowntopdir=False):
+    """Recursively change user and group ownership of files and directories
+    in given path. Doesn't chown path itself by default, only its children.
+
+    :param str path: The string path to start changing ownership.
+    :param str owner: The owner string to use when looking up the uid.
+    :param str group: The group string to use when looking up the gid.
+    :param bool follow_links: Also follow and chown links if True
+    :param bool chowntopdir: Also chown path itself if True
+    """
     uid = pwd.getpwnam(owner).pw_uid
     gid = grp.getgrnam(group).gr_gid
     if follow_links:
@@ -438,7 +825,11 @@
     else:
         chown = os.lchown
 
-    for root, dirs, files in os.walk(path):
+    if chowntopdir:
+        broken_symlink = os.path.lexists(path) and not os.path.exists(path)
+        if not broken_symlink:
+            chown(path, uid, gid)
+    for root, dirs, files in os.walk(path, followlinks=follow_links):
         for name in dirs + files:
             full = os.path.join(root, name)
             broken_symlink = os.path.lexists(full) and not os.path.exists(full)
@@ -447,4 +838,81 @@
 
 
 def lchownr(path, owner, group):
+    """Recursively change user and group ownership of files and directories
+    in a given path, not following symbolic links. See the documentation for
+    'os.lchown' for more information.
+
+    :param str path: The string path to start changing ownership.
+    :param str owner: The owner string to use when looking up the uid.
+    :param str group: The group string to use when looking up the gid.
+    """
     chownr(path, owner, group, follow_links=False)
+
+
+def owner(path):
+    """Returns a tuple containing the username & groupname owning the path.
+
+    :param str path: the string path to retrieve the ownership
+    :return tuple(str, str): A (username, groupname) tuple containing the
+                             name of the user and group owning the path.
+    :raises OSError: if the specified path does not exist
+    """
+    stat = os.stat(path)
+    username = pwd.getpwuid(stat.st_uid)[0]
+    groupname = grp.getgrgid(stat.st_gid)[0]
+    return username, groupname
+
+
+def get_total_ram():
+    """The total amount of system RAM in bytes.
+
+    This is what is reported by the OS, and may be overcommitted when
+    there are multiple containers hosted on the same machine.
+    """
+    with open('/proc/meminfo', 'r') as f:
+        for line in f.readlines():
+            if line:
+                key, value, unit = line.split()
+                if key == 'MemTotal:':
+                    assert unit == 'kB', 'Unknown unit'
+                    return int(value) * 1024  # Classic, not KiB.
+        raise NotImplementedError()
+
+
+UPSTART_CONTAINER_TYPE = '/run/container_type'
+
+
+def is_container():
+    """Determine whether unit is running in a container
+
+    @return: boolean indicating if unit is in a container
+    """
+    if init_is_systemd():
+        # Detect using systemd-detect-virt
+        return subprocess.call(['systemd-detect-virt',
+                                '--container']) == 0
+    else:
+        # Detect using upstart container file marker
+        return os.path.exists(UPSTART_CONTAINER_TYPE)
+
+
+def add_to_updatedb_prunepath(path, updatedb_path=UPDATEDB_PATH):
+    with open(updatedb_path, 'r+') as f_id:
+        updatedb_text = f_id.read()
+        output = updatedb(updatedb_text, path)
+        f_id.seek(0)
+        f_id.write(output)
+        f_id.truncate()
+
+
+def updatedb(updatedb_text, new_path):
+    lines = [line for line in updatedb_text.split("\n")]
+    for i, line in enumerate(lines):
+        if line.startswith("PRUNEPATHS="):
+            paths_line = line.split("=")[1].replace('"', '')
+            paths = paths_line.split(" ")
+            if new_path not in paths:
+                paths.append(new_path)
+                lines[i] = 'PRUNEPATHS="{}"'.format(' '.join(paths))
+    output = "\n".join(lines)
+    return output

=== added directory 'hooks/charmhelpers/core/host_factory'
=== added file 'hooks/charmhelpers/core/host_factory/__init__.py'
=== added file 'hooks/charmhelpers/core/host_factory/centos.py'
--- hooks/charmhelpers/core/host_factory/centos.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/host_factory/centos.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,56 @@
+import subprocess
+import yum
+import os
+
+
+def service_available(service_name):
+    # """Determine whether a system service is available."""
+    if os.path.isdir('/run/systemd/system'):
+        cmd = ['systemctl', 'is-enabled', service_name]
+    else:
+        cmd = ['service', service_name, 'is-enabled']
+    return subprocess.call(cmd) == 0
+
+
+def add_new_group(group_name, system_group=False, gid=None):
+    cmd = ['groupadd']
+    if gid:
+        cmd.extend(['--gid', str(gid)])
+    if system_group:
+        cmd.append('-r')
+    cmd.append(group_name)
+    subprocess.check_call(cmd)
+
+
+def lsb_release():
+    """Return /etc/os-release in a dict."""
+    d = {}
+    with open('/etc/os-release', 'r') as lsb:
+        for l in lsb:
+            s = l.split('=')
+            if len(s) != 2:
+                continue
+            d[s[0].strip()] = s[1].strip()
+    return d
+
+
+def cmp_pkgrevno(package, revno, pkgcache=None):
+    """Compare supplied revno with the revno of the installed package.
+
+    *  1 => Installed revno is greater than supplied arg
+    *  0 => Installed revno is the same as supplied arg
+    * -1 => Installed revno is less than supplied arg
+
+    This function imports YumBase function if the pkgcache argument
+    is None.
+    """
+    if not pkgcache:
+        y = yum.YumBase()
+        packages = y.doPackageLists()
+        pkgcache = {i.Name: i.version for i in packages['installed']}
+    pkg = pkgcache[package]
+    if pkg > revno:
+        return 1
+    if pkg < revno:
+        return -1
+    return 0

=== added file 'hooks/charmhelpers/core/host_factory/ubuntu.py'
--- hooks/charmhelpers/core/host_factory/ubuntu.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/host_factory/ubuntu.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,56 @@
+import subprocess
+
+
+def service_available(service_name):
+    """Determine whether a system service is available"""
+    try:
+        subprocess.check_output(
+            ['service', service_name, 'status'],
+            stderr=subprocess.STDOUT).decode('UTF-8')
+    except subprocess.CalledProcessError as e:
+        return b'unrecognized service' not in e.output
+    else:
+        return True
+
+
+def add_new_group(group_name, system_group=False, gid=None):
+    cmd = ['addgroup']
+    if gid:
+        cmd.extend(['--gid', str(gid)])
+    if system_group:
+        cmd.append('--system')
+    else:
+        cmd.extend([
+            '--group',
+        ])
+    cmd.append(group_name)
+    subprocess.check_call(cmd)
+
+
+def lsb_release():
+    """Return /etc/lsb-release in a dict"""
+    d = {}
+    with open('/etc/lsb-release', 'r') as lsb:
+        for l in lsb:
+            k, v = l.split('=')
+            d[k.strip()] = v.strip()
+    return d
+
+
+def cmp_pkgrevno(package, revno, pkgcache=None):
+    """Compare supplied revno with the revno of the installed package.
+
+    *  1 => Installed revno is greater than supplied arg
+    *  0 => Installed revno is the same as supplied arg
+    * -1 => Installed revno is less than supplied arg
+
+    This function imports apt_cache function from charmhelpers.fetch if
+    the pkgcache argument is None. Be sure to add charmhelpers.fetch if
+    you call this function, or pass an apt_pkg.Cache() instance.
+    """
+    import apt_pkg
+    if not pkgcache:
+        from charmhelpers.fetch import apt_cache
+        pkgcache = apt_cache()
+    pkg = pkgcache[package]
+    return apt_pkg.version_compare(pkg.current_ver.ver_str, revno)

=== added file 'hooks/charmhelpers/core/hugepage.py'
--- hooks/charmhelpers/core/hugepage.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/hugepage.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2014-2015 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import yaml
+from charmhelpers.core import fstab
+from charmhelpers.core import sysctl
+from charmhelpers.core.host import (
+    add_group,
+    add_user_to_group,
+    fstab_mount,
+    mkdir,
+)
+from charmhelpers.core.strutils import bytes_from_string
+from subprocess import check_output
+
+
+def hugepage_support(user, group='hugetlb', nr_hugepages=256,
+                     max_map_count=65536, mnt_point='/run/hugepages/kvm',
+                     pagesize='2MB', mount=True, set_shmmax=False):
+    """Enable hugepages on system.
+
+    Args:
+    user (str)  -- Username to allow access to hugepages to
+    group (str) -- Group name to own hugepages
+    nr_hugepages (int) -- Number of pages to reserve
+    max_map_count (int) -- Number of Virtual Memory Areas a process can own
+    mnt_point (str) -- Directory to mount hugepages on
+    pagesize (str) -- Size of hugepages
+    mount (bool) -- Whether to Mount hugepages
+    """
+    group_info = add_group(group)
+    gid = group_info.gr_gid
+    add_user_to_group(user, group)
+    if max_map_count < 2 * nr_hugepages:
+        max_map_count = 2 * nr_hugepages
+    sysctl_settings = {
+        'vm.nr_hugepages': nr_hugepages,
+        'vm.max_map_count': max_map_count,
+        'vm.hugetlb_shm_group': gid,
+    }
+    if set_shmmax:
+        shmmax_current = int(check_output(['sysctl', '-n', 'kernel.shmmax']))
+        shmmax_minsize = bytes_from_string(pagesize) * nr_hugepages
+        if shmmax_minsize > shmmax_current:
+            sysctl_settings['kernel.shmmax'] = shmmax_minsize
+    sysctl.create(yaml.dump(sysctl_settings), '/etc/sysctl.d/10-hugepage.conf')
+    mkdir(mnt_point, owner='root', group='root', perms=0o755, force=False)
+    lfstab = fstab.Fstab()
+    fstab_entry = lfstab.get_entry_by_attr('mountpoint', mnt_point)
+    if fstab_entry:
+        lfstab.remove_entry(fstab_entry)
+    entry = lfstab.Entry('nodev', mnt_point, 'hugetlbfs',
+                         'mode=1770,gid={},pagesize={}'.format(gid, pagesize), 0, 0)
+    lfstab.add_entry(entry)
+    if mount:
+        fstab_mount(mnt_point)

=== added file 'hooks/charmhelpers/core/kernel.py'
--- hooks/charmhelpers/core/kernel.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/kernel.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,72 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Copyright 2014-2015 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+import subprocess
+
+from charmhelpers.osplatform import get_platform
+from charmhelpers.core.hookenv import (
+    log,
+    INFO
+)
+
+__platform__ = get_platform()
+if __platform__ == "ubuntu":
+    from charmhelpers.core.kernel_factory.ubuntu import (
+        persistent_modprobe,
+        update_initramfs,
+    )  # flake8: noqa -- ignore F401 for this import
+elif __platform__ == "centos":
+    from charmhelpers.core.kernel_factory.centos import (
+        persistent_modprobe,
+        update_initramfs,
+    )  # flake8: noqa -- ignore F401 for this import
+
+__author__ = "Jorge Niedbalski <[e-mail]>"
+
+
+def modprobe(module, persist=True):
+    """Load a kernel module and configure for auto-load on reboot."""
+    cmd = ['modprobe', module]
+
+    log('Loading kernel module %s' % module, level=INFO)
+
+    subprocess.check_call(cmd)
+    if persist:
+        persistent_modprobe(module)
+
+
+def rmmod(module, force=False):
+    """Remove a module from the linux kernel"""
+    cmd = ['rmmod']
+    if force:
+        cmd.append('-f')
+    cmd.append(module)
+    log('Removing kernel module %s' % module, level=INFO)
+    return subprocess.check_call(cmd)
+
+
+def lsmod():
+    """Shows what kernel modules are currently loaded"""
+    return subprocess.check_output(['lsmod'],
+                                   universal_newlines=True)
+
+
+def is_module_loaded(module):
+    """Checks if a kernel module is already loaded"""
+    matches = re.findall('^%s[ ]+' % module, lsmod(), re.M)
+    return len(matches) > 0

=== added directory 'hooks/charmhelpers/core/kernel_factory'
=== added file 'hooks/charmhelpers/core/kernel_factory/__init__.py'
=== added file 'hooks/charmhelpers/core/kernel_factory/centos.py'
--- hooks/charmhelpers/core/kernel_factory/centos.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/kernel_factory/centos.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,17 @@
+import subprocess
+import os
+
+
+def persistent_modprobe(module):
+    """Load a kernel module and configure for auto-load on reboot."""
+    if not os.path.exists('/etc/rc.modules'):
+        open('/etc/rc.modules', 'a')
+        os.chmod('/etc/rc.modules', 111)
+    with open('/etc/rc.modules', 'r+') as modules:
+        if module not in modules.read():
+            modules.write('modprobe %s\n' % module)
+
+
+def update_initramfs(version='all'):
+    """Updates an initramfs image."""
+    return subprocess.check_call(["dracut", "-f", version])

=== added file 'hooks/charmhelpers/core/kernel_factory/ubuntu.py'
--- hooks/charmhelpers/core/kernel_factory/ubuntu.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/core/kernel_factory/ubuntu.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,13 @@
+import subprocess
+
+
+def persistent_modprobe(module):
+    """Load a kernel module and configure for auto-load on reboot."""
+    with open('/etc/modules', 'r+') as modules:
+        if module not in modules.read():
+            modules.write(module + "\n")
+
+
+def update_initramfs(version='all'):
+    """Updates an initramfs image."""
+    return subprocess.check_call(["update-initramfs", "-k", version, "-u"])

=== modified file 'hooks/charmhelpers/core/services/__init__.py'
--- hooks/charmhelpers/core/services/__init__.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/services/__init__.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 from .base import *  # NOQA
 from .helpers import *  # NOQA

=== modified file 'hooks/charmhelpers/core/services/base.py'
--- hooks/charmhelpers/core/services/base.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/services/base.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
 import json
@@ -128,15 +126,18 @@
         """
         Handle the current hook by doing The Right Thing with the registered services.
         """
-        hook_name = hookenv.hook_name()
-        if hook_name == 'stop':
-            self.stop_services()
-        else:
-            self.reconfigure_services()
-            self.provide_data()
-        cfg = hookenv.config()
-        if cfg.implicit_save:
-            cfg.save()
+        hookenv._run_atstart()
+        try:
+            hook_name = hookenv.hook_name()
+            if hook_name == 'stop':
+                self.stop_services()
+            else:
+                self.reconfigure_services()
+                self.provide_data()
+        except SystemExit as x:
+            if x.code is None or x.code == 0:
+                hookenv._run_atexit()
+        hookenv._run_atexit()
 
     def provide_data(self):
         """

=== modified file 'hooks/charmhelpers/core/services/helpers.py'
--- hooks/charmhelpers/core/services/helpers.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/services/helpers.py	2017-03-03 23:04:07 +0000
@@ -1,22 +1,22 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
 import yaml
+
 from charmhelpers.core import hookenv
+from charmhelpers.core import host
 from charmhelpers.core import templating
 
 from charmhelpers.core.services.base import ManagerCallback
@@ -239,28 +239,51 @@
     action.
 
     :param str source: The template source file, relative to
-    `$CHARM_DIR/templates`
+        `$CHARM_DIR/templates`
 
-    :param str target: The target to write the rendered template to
+    :param str target: The target to write the rendered template to (or None)
     :param str owner: The owner of the rendered file
     :param str group: The group of the rendered file
     :param int perms: The permissions of the rendered file
+    :param partial on_change_action: functools partial to be executed when
+                                     rendered file changes
+    :param jinja2 loader template_loader: A jinja2 template loader
+
+    :return str: The rendered template
     """
     def __init__(self, source, target,
-                 owner='root', group='root', perms=0o444):
+                 owner='root', group='root', perms=0o444,
+                 on_change_action=None, template_loader=None):
         self.source = source
         self.target = target
         self.owner = owner
         self.group = group
         self.perms = perms
+        self.on_change_action = on_change_action
+        self.template_loader = template_loader
 
     def __call__(self, manager, service_name, event_name):
+        pre_checksum = ''
+        if self.on_change_action and os.path.isfile(self.target):
+            pre_checksum = host.file_hash(self.target)
         service = manager.get_service(service_name)
-        context = {}
+        context = {'ctx': {}}
         for ctx in service.get('required_data', []):
             context.update(ctx)
-        templating.render(self.source, self.target, context,
-                          self.owner, self.group, self.perms)
+            context['ctx'].update(ctx)
+
+        result = templating.render(self.source, self.target, context,
+                                   self.owner, self.group, self.perms,
+                                   template_loader=self.template_loader)
+        if self.on_change_action:
+            if pre_checksum == host.file_hash(self.target):
+                hookenv.log(
+                    'No change detected: {}'.format(self.target),
+                    hookenv.DEBUG)
+            else:
+                self.on_change_action()
+
+        return result
 
 
 # Convenience aliases for templates

=== modified file 'hooks/charmhelpers/core/strutils.py'
--- hooks/charmhelpers/core/strutils.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/strutils.py	2017-03-03 23:04:07 +0000
@@ -3,21 +3,20 @@
 
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import six
+import re
 
 
 def bool_from_string(value):
@@ -40,3 +39,32 @@
 
     msg = "Unable to interpret string value '%s' as boolean" % (value)
     raise ValueError(msg)
+
+
+def bytes_from_string(value):
+    """Interpret human readable string value as bytes.
+
+    Returns int
+    """
+    BYTE_POWER = {
+        'K': 1,
+        'KB': 1,
+        'M': 2,
+        'MB': 2,
+        'G': 3,
+        'GB': 3,
+        'T': 4,
+        'TB': 4,
+        'P': 5,
+        'PB': 5,
+    }
+    if isinstance(value, six.string_types):
+        value = six.text_type(value)
+    else:
+        msg = "Unable to interpret non-string value '%s' as boolean" % (value)
+        raise ValueError(msg)
+    matches = re.match("([0-9]+)([a-zA-Z]+)", value)
+    if not matches:
+        msg = "Unable to interpret string value '%s' as bytes" % (value)
+        raise ValueError(msg)
+    return int(matches.group(1)) * (1024 ** BYTE_POWER[matches.group(2)])

=== modified file 'hooks/charmhelpers/core/sysctl.py'
--- hooks/charmhelpers/core/sysctl.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/sysctl.py	2017-03-03 23:04:07 +0000
@@ -3,19 +3,17 @@
 
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import yaml
 

=== modified file 'hooks/charmhelpers/core/templating.py'
--- hooks/charmhelpers/core/templating.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/templating.py	2017-03-03 23:04:07 +0000
@@ -1,33 +1,33 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
+import sys
 
 from charmhelpers.core import host
 from charmhelpers.core import hookenv
 
 
 def render(source, target, context, owner='root', group='root',
-           perms=0o444, templates_dir=None, encoding='UTF-8'):
+           perms=0o444, templates_dir=None, encoding='UTF-8', template_loader=None):
     """
     Render a template.
 
     The `source` path, if not absolute, is relative to the `templates_dir`.
 
-    The `target` path should be absolute.
+    The `target` path should be absolute.  It can also be `None`, in which
+    case no file will be written.
 
     The context should be a dict containing the values to be replaced in the
     template.
@@ -36,8 +36,12 @@
 
     If omitted, `templates_dir` defaults to the `templates` folder in the charm.
 
-    Note: Using this requires python-jinja2; if it is not installed, calling
-    this will attempt to use charmhelpers.fetch.apt_install to install it.
+    The rendered template will be written to the file as well as being returned
+    as a string.
+
+    Note: Using this requires python-jinja2 or python3-jinja2; if it is not
+    installed, calling this will attempt to use charmhelpers.fetch.apt_install
+    to install it.
     """
     try:
         from jinja2 import FileSystemLoader, Environment, exceptions
@@ -49,20 +53,32 @@
                         'charmhelpers.fetch to install it',
                         level=hookenv.ERROR)
             raise
-        apt_install('python-jinja2', fatal=True)
+        if sys.version_info.major == 2:
+            apt_install('python-jinja2', fatal=True)
+        else:
+            apt_install('python3-jinja2', fatal=True)
         from jinja2 import FileSystemLoader, Environment, exceptions
 
-    if templates_dir is None:
-        templates_dir = os.path.join(hookenv.charm_dir(), 'templates')
-    loader = Environment(loader=FileSystemLoader(templates_dir))
+    if template_loader:
+        template_env = Environment(loader=template_loader)
+    else:
+        if templates_dir is None:
+            templates_dir = os.path.join(hookenv.charm_dir(), 'templates')
+        template_env = Environment(loader=FileSystemLoader(templates_dir))
     try:
         source = source
-        template = loader.get_template(source)
+        template = template_env.get_template(source)
     except exceptions.TemplateNotFound as e:
         hookenv.log('Could not load template %s from %s.' %
                     (source, templates_dir),
                     level=hookenv.ERROR)
         raise e
     content = template.render(context)
-    host.mkdir(os.path.dirname(target), owner, group, perms=0o755)
-    host.write_file(target, content.encode(encoding), owner, group, perms)
+    if target is not None:
+        target_dir = os.path.dirname(target)
+        if not os.path.exists(target_dir):
+            # This is a terrible default directory permission, as the file
+            # or its siblings will often contain secrets.
+            host.mkdir(os.path.dirname(target), owner, group, perms=0o755)
+        host.write_file(target, content.encode(encoding), owner, group, perms)
+    return content

=== modified file 'hooks/charmhelpers/core/unitdata.py'
--- hooks/charmhelpers/core/unitdata.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/core/unitdata.py	2017-03-03 23:04:07 +0000
@@ -3,20 +3,17 @@
 #
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
-#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 #
 # Authors:
 #  Kapil Thangavelu <[e-mail]>
@@ -152,6 +149,7 @@
 import collections
 import contextlib
 import datetime
+import itertools
 import json
 import os
 import pprint
@@ -164,8 +162,7 @@
 class Storage(object):
     """Simple key value database for local unit state within charms.
 
-    Modifications are automatically committed at hook exit. That's
-    currently regardless of exit code.
+    Modifications are not persisted unless :meth:`flush` is called.
 
     To support dicts, lists, integer, floats, and booleans values
     are automatically json encoded/decoded.
@@ -173,8 +170,11 @@
     def __init__(self, path=None):
         self.db_path = path
         if path is None:
-            self.db_path = os.path.join(
-                os.environ.get('CHARM_DIR', ''), '.unit-state.db')
+            if 'UNIT_STATE_DB' in os.environ:
+                self.db_path = os.environ['UNIT_STATE_DB']
+            else:
+                self.db_path = os.path.join(
+                    os.environ.get('CHARM_DIR', ''), '.unit-state.db')
         self.conn = sqlite3.connect('%s' % self.db_path)
         self.cursor = self.conn.cursor()
         self.revision = None
@@ -189,15 +189,8 @@
         self.conn.close()
         self._closed = True
 
-    def _scoped_query(self, stmt, params=None):
-        if params is None:
-            params = []
-        return stmt, params
-
     def get(self, key, default=None, record=False):
-        self.cursor.execute(
-            *self._scoped_query(
-                'select data from kv where key=?', [key]))
+        self.cursor.execute('select data from kv where key=?', [key])
         result = self.cursor.fetchone()
         if not result:
             return default
@@ -206,33 +199,81 @@
         return json.loads(result[0])
 
     def getrange(self, key_prefix, strip=False):
-        stmt = "select key, data from kv where key like '%s%%'" % key_prefix
-        self.cursor.execute(*self._scoped_query(stmt))
+        """
+        Get a range of keys starting with a common prefix as a mapping of
+        keys to values.
+
+        :param str key_prefix: Common prefix among all keys
+        :param bool strip: Optionally strip the common prefix from the key
+            names in the returned dict
+        :return dict: A (possibly empty) dict of key-value mappings
+        """
+        self.cursor.execute("select key, data from kv where key like ?",
+                            ['%s%%' % key_prefix])
         result = self.cursor.fetchall()
 
         if not result:
-            return None
+            return {}
         if not strip:
             key_prefix = ''
         return dict([
             (k[len(key_prefix):], json.loads(v)) for k, v in result])
 
     def update(self, mapping, prefix=""):
+        """
+        Set the values of multiple keys at once.
+
+        :param dict mapping: Mapping of keys to values
+        :param str prefix: Optional prefix to apply to all keys in `mapping`
+            before setting
+        """
         for k, v in mapping.items():
             self.set("%s%s" % (prefix, k), v)
 
     def unset(self, key):
+        """
+        Remove a key from the database entirely.
+        """
         self.cursor.execute('delete from kv where key=?', [key])
         if self.revision and self.cursor.rowcount:
             self.cursor.execute(
                 'insert into kv_revisions values (?, ?, ?)',
                 [key, self.revision, json.dumps('DELETED')])
 
+    def unsetrange(self, keys=None, prefix=""):
+        """
+        Remove a range of keys starting with a common prefix, from the database
+        entirely.
+
+        :param list keys: List of keys to remove.
+        :param str prefix: Optional prefix to apply to all keys in ``keys``
+            before removing.
+        """
+        if keys is not None:
+            keys = ['%s%s' % (prefix, key) for key in keys]
+            self.cursor.execute('delete from kv where key in (%s)' % ','.join(['?'] * len(keys)), keys)
+            if self.revision and self.cursor.rowcount:
+                self.cursor.execute(
+                    'insert into kv_revisions values %s' % ','.join(['(?, ?, ?)'] * len(keys)),
+                    list(itertools.chain.from_iterable((key, self.revision, json.dumps('DELETED')) for key in keys)))
+        else:
+            self.cursor.execute('delete from kv where key like ?',
+                                ['%s%%' % prefix])
+            if self.revision and self.cursor.rowcount:
+                self.cursor.execute(
+                    'insert into kv_revisions values (?, ?, ?)',
+                    ['%s%%' % prefix, self.revision, json.dumps('DELETED')])
+
     def set(self, key, value):
+        """
+        Set a value in the database.
+
+        :param str key: Key to set the value for
+        :param value: Any JSON-serializable value to be set
+        """
         serialized = json.dumps(value)
 
-        self.cursor.execute(
-            'select data from kv where key=?', [key])
+        self.cursor.execute('select data from kv where key=?', [key])
         exists = self.cursor.fetchone()
 
         # Skip mutations to the same value

=== modified file 'hooks/charmhelpers/fetch/__init__.py'
--- hooks/charmhelpers/fetch/__init__.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/fetch/__init__.py	2017-03-03 23:04:07 +0000
@@ -1,32 +1,24 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import importlib
-from tempfile import NamedTemporaryFile
-import time
+from charmhelpers.osplatform import get_platform
 from yaml import safe_load
-from charmhelpers.core.host import (
-    lsb_release
-)
-import subprocess
 from charmhelpers.core.hookenv import (
     config,
     log,
 )
-import os
 
 import six
 if six.PY3:
@@ -35,63 +27,6 @@
     from urlparse import urlparse, urlunparse
 
 
-CLOUD_ARCHIVE = """# Ubuntu Cloud Archive
-deb http://ubuntu-cloud.archive.canonical.com/ubuntu {} main
-"""
-PROPOSED_POCKET = """# Proposed
-deb http://archive.ubuntu.com/ubuntu {}-proposed main universe multiverse restricted
-"""
-CLOUD_ARCHIVE_POCKETS = {
-    # Folsom
-    'folsom': 'precise-updates/folsom',
-    'precise-folsom': 'precise-updates/folsom',
-    'precise-folsom/updates': 'precise-updates/folsom',
-    'precise-updates/folsom': 'precise-updates/folsom',
-    'folsom/proposed': 'precise-proposed/folsom',
-    'precise-folsom/proposed': 'precise-proposed/folsom',
-    'precise-proposed/folsom': 'precise-proposed/folsom',
-    # Grizzly
-    'grizzly': 'precise-updates/grizzly',
-    'precise-grizzly': 'precise-updates/grizzly',
-    'precise-grizzly/updates': 'precise-updates/grizzly',
-    'precise-updates/grizzly': 'precise-updates/grizzly',
-    'grizzly/proposed': 'precise-proposed/grizzly',
-    'precise-grizzly/proposed': 'precise-proposed/grizzly',
-    'precise-proposed/grizzly': 'precise-proposed/grizzly',
-    # Havana
-    'havana': 'precise-updates/havana',
-    'precise-havana': 'precise-updates/havana',
-    'precise-havana/updates': 'precise-updates/havana',
-    'precise-updates/havana': 'precise-updates/havana',
-    'havana/proposed': 'precise-proposed/havana',
-    'precise-havana/proposed': 'precise-proposed/havana',
-    'precise-proposed/havana': 'precise-proposed/havana',
-    # Icehouse
-    'icehouse': 'precise-updates/icehouse',
-    'precise-icehouse': 'precise-updates/icehouse',
-    'precise-icehouse/updates': 'precise-updates/icehouse',
-    'precise-updates/icehouse': 'precise-updates/icehouse',
-    'icehouse/proposed': 'precise-proposed/icehouse',
-    'precise-icehouse/proposed': 'precise-proposed/icehouse',
-    'precise-proposed/icehouse': 'precise-proposed/icehouse',
-    # Juno
-    'juno': 'trusty-updates/juno',
-    'trusty-juno': 'trusty-updates/juno',
-    'trusty-juno/updates': 'trusty-updates/juno',
-    'trusty-updates/juno': 'trusty-updates/juno',
-    'juno/proposed': 'trusty-proposed/juno',
-    'trusty-juno/proposed': 'trusty-proposed/juno',
-    'trusty-proposed/juno': 'trusty-proposed/juno',
-    # Kilo
-    'kilo': 'trusty-updates/kilo',
-    'trusty-kilo': 'trusty-updates/kilo',
-    'trusty-kilo/updates': 'trusty-updates/kilo',
-    'trusty-updates/kilo': 'trusty-updates/kilo',
-    'kilo/proposed': 'trusty-proposed/kilo',
-    'trusty-kilo/proposed': 'trusty-proposed/kilo',
-    'trusty-proposed/kilo': 'trusty-proposed/kilo',
-}
-
 # The order of this list is very important. Handlers should be listed in from
 # least- to most-specific URL matching.
 FETCH_HANDLERS = (
@@ -100,10 +35,6 @@
     'charmhelpers.fetch.giturl.GitUrlFetchHandler',
 )
 
-APT_NO_LOCK = 100  # The return code for "couldn't acquire lock" in APT.
-APT_NO_LOCK_RETRY_DELAY = 10  # Wait 10 seconds between apt lock checks.
-APT_NO_LOCK_RETRY_COUNT = 30  # Retry to acquire the lock X times.
-
 
 class SourceConfigError(Exception):
     pass
@@ -141,172 +72,38 @@
         return urlunparse(parts)
 
 
-def filter_installed_packages(packages):
-    """Returns a list of packages that require installation"""
-    cache = apt_cache()
-    _pkgs = []
-    for package in packages:
-        try:
-            p = cache[package]
-            p.current_ver or _pkgs.append(package)
-        except KeyError:
-            log('Package {} has no installation candidate.'.format(package),
-                level='WARNING')
-            _pkgs.append(package)
-    return _pkgs
-
-
-def apt_cache(in_memory=True):
-    """Build and return an apt cache"""
-    from apt import apt_pkg
-    apt_pkg.init()
-    if in_memory:
-        apt_pkg.config.set("Dir::Cache::pkgcache", "")
-        apt_pkg.config.set("Dir::Cache::srcpkgcache", "")
-    return apt_pkg.Cache()
-
-
-def apt_install(packages, options=None, fatal=False):
-    """Install one or more packages"""
-    if options is None:
-        options = ['--option=Dpkg::Options::=--force-confold']
-
-    cmd = ['apt-get', '--assume-yes']
-    cmd.extend(options)
-    cmd.append('install')
-    if isinstance(packages, six.string_types):
-        cmd.append(packages)
-    else:
-        cmd.extend(packages)
-    log("Installing {} with options: {}".format(packages,
-                                                options))
-    _run_apt_command(cmd, fatal)
-
-
-def apt_upgrade(options=None, fatal=False, dist=False):
-    """Upgrade all packages"""
-    if options is None:
-        options = ['--option=Dpkg::Options::=--force-confold']
-
-    cmd = ['apt-get', '--assume-yes']
-    cmd.extend(options)
-    if dist:
-        cmd.append('dist-upgrade')
-    else:
-        cmd.append('upgrade')
-    log("Upgrading with options: {}".format(options))
-    _run_apt_command(cmd, fatal)
-
-
-def apt_update(fatal=False):
-    """Update local apt cache"""
-    cmd = ['apt-get', 'update']
-    _run_apt_command(cmd, fatal)
-
-
-def apt_purge(packages, fatal=False):
-    """Purge one or more packages"""
-    cmd = ['apt-get', '--assume-yes', 'purge']
-    if isinstance(packages, six.string_types):
-        cmd.append(packages)
-    else:
-        cmd.extend(packages)
-    log("Purging {}".format(packages))
-    _run_apt_command(cmd, fatal)
-
-
-def apt_hold(packages, fatal=False):
-    """Hold one or more packages"""
-    cmd = ['apt-mark', 'hold']
-    if isinstance(packages, six.string_types):
-        cmd.append(packages)
-    else:
-        cmd.extend(packages)
-    log("Holding {}".format(packages))
-
-    if fatal:
-        subprocess.check_call(cmd)
-    else:
-        subprocess.call(cmd)
-
-
-def add_source(source, key=None):
-    """Add a package source to this system.
-
-    @param source: a URL or sources.list entry, as supported by
-    add-apt-repository(1). Examples::
-
-        ppa:charmers/example
-        deb https://stub:[e-mail]/ubuntu trusty main
-
-    In addition:
-        'proposed:' may be used to enable the standard 'proposed'
-        pocket for the release.
-        'cloud:' may be used to activate official cloud archive pockets,
-        such as 'cloud:icehouse'
-        'distro' may be used as a noop
-
-    @param key: A key to be added to the system's APT keyring and used
-    to verify the signatures on packages. Ideally, this should be an
-    ASCII format GPG public key including the block headers. A GPG key
-    id may also be used, but be aware that only insecure protocols are
-    available to retrieve the actual public key from a public keyserver
-    placing your Juju environment at risk. ppa and cloud archive keys
-    are securely added automtically, so sould not be provided.
-    """
-    if source is None:
-        log('Source is not present. Skipping')
-        return
-
-    if (source.startswith('ppa:') or
-        source.startswith('http') or
-        source.startswith('deb ') or
-            source.startswith('cloud-archive:')):
-        subprocess.check_call(['add-apt-repository', '--yes', source])
-    elif source.startswith('cloud:'):
-        apt_install(filter_installed_packages(['ubuntu-cloud-keyring']),
-                    fatal=True)
-        pocket = source.split(':')[-1]
-        if pocket not in CLOUD_ARCHIVE_POCKETS:
-            raise SourceConfigError(
-                'Unsupported cloud: source option %s' %
-                pocket)
-        actual_pocket = CLOUD_ARCHIVE_POCKETS[pocket]
-        with open('/etc/apt/sources.list.d/cloud-archive.list', 'w') as apt:
-            apt.write(CLOUD_ARCHIVE.format(actual_pocket))
-    elif source == 'proposed':
-        release = lsb_release()['DISTRIB_CODENAME']
-        with open('/etc/apt/sources.list.d/proposed.list', 'w') as apt:
-            apt.write(PROPOSED_POCKET.format(release))
-    elif source == 'distro':
-        pass
-    else:
-        log("Unknown source: {!r}".format(source))
-
-    if key:
-        if '-----BEGIN PGP PUBLIC KEY BLOCK-----' in key:
-            with NamedTemporaryFile('w+') as key_file:
-                key_file.write(key)
-                key_file.flush()
-                key_file.seek(0)
-                subprocess.check_call(['apt-key', 'add', '-'], stdin=key_file)
-        else:
-            # Note that hkp: is in no way a secure protocol. Using a
-            # GPG key id is pointless from a security POV unless you
-            # absolutely trust your network and DNS.
-            subprocess.check_call(['apt-key', 'adv', '--keyserver',
-                                   'hkp://keyserver.ubuntu.com:80', '--recv',
-                                   key])
+__platform__ = get_platform()
+module = "charmhelpers.fetch.%s" % __platform__
+fetch = importlib.import_module(module)
+
+filter_installed_packages = fetch.filter_installed_packages
+install = fetch.install
+upgrade = fetch.upgrade
+update = fetch.update
+purge = fetch.purge
+add_source = fetch.add_source
+
+if __platform__ == "ubuntu":
+    apt_cache = fetch.apt_cache
+    apt_install = fetch.install
+    apt_update = fetch.update
+    apt_upgrade = fetch.upgrade
+    apt_purge = fetch.purge
+    apt_mark = fetch.apt_mark
+    apt_hold = fetch.apt_hold
+    apt_unhold = fetch.apt_unhold
+    get_upstream_version = fetch.get_upstream_version
+elif __platform__ == "centos":
+    yum_search = fetch.yum_search
 
 
 def configure_sources(update=False,
                       sources_var='install_sources',
                       keys_var='install_keys'):
-    """
-    Configure multiple sources from charm configuration.
+    """Configure multiple sources from charm configuration.
 
     The lists are encoded as yaml fragments in the configuration.
-    The frament needs to be included as a string. Sources and their
+    The fragment needs to be included as a string. Sources and their
     corresponding keys are of the types supported by add_source().
 
     Example config:
@@ -338,12 +135,11 @@
         for source, key in zip(sources, keys):
             add_source(source, key)
     if update:
-        apt_update(fatal=True)
+        fetch.update(fatal=True)
 
 
 def install_remote(source, *args, **kwargs):
-    """
-    Install a file tree from a remote source
+    """Install a file tree from a remote source.
 
     The specified source should be a url of the form:
         scheme://[host]/path[#[option=value][&...]]
@@ -366,18 +162,17 @@
     # We ONLY check for True here because can_handle may return a string
     # explaining why it can't handle a given source.
     handlers = [h for h in plugins() if h.can_handle(source) is True]
-    installed_to = None
     for handler in handlers:
         try:
-            installed_to = handler.install(source, *args, **kwargs)
-        except UnhandledSource:
-            pass
-    if not installed_to:
-        raise UnhandledSource("No handler found for source {}".format(source))
-    return installed_to
+            return handler.install(source, *args, **kwargs)
+        except UnhandledSource as e:
+            log('Install source attempt unsuccessful: {}'.format(e),
+                level='WARNING')
+    raise UnhandledSource("No handler found for source {}".format(source))
 
 
 def install_from_config(config_var_name):
+    """Install a file from config."""
     charm_config = config()
     source = charm_config[config_var_name]
     return install_remote(source)
@@ -394,46 +189,9 @@
                 importlib.import_module(package),
                 classname)
             plugin_list.append(handler_class())
-        except (ImportError, AttributeError):
+        except NotImplementedError:
             # Skip missing plugins so that they can be ommitted from
             # installation if desired
             log("FetchHandler {} not found, skipping plugin".format(
                 handler_name))
     return plugin_list
-
-
-def _run_apt_command(cmd, fatal=False):
-    """
-    Run an APT command, checking output and retrying if the fatal flag is set
-    to True.
-
-    :param: cmd: str: The apt command to run.
-    :param: fatal: bool: Whether the command's output should be checked and
-        retried.
-    """
-    env = os.environ.copy()
-
-    if 'DEBIAN_FRONTEND' not in env:
-        env['DEBIAN_FRONTEND'] = 'noninteractive'
-
-    if fatal:
-        retry_count = 0
-        result = None
-
-        # If the command is considered "fatal", we need to retry if the apt
-        # lock was not acquired.
-
-        while result is None or result == APT_NO_LOCK:
-            try:
-                result = subprocess.check_call(cmd, env=env)
-            except subprocess.CalledProcessError as e:
-                retry_count = retry_count + 1
-                if retry_count > APT_NO_LOCK_RETRY_COUNT:
-                    raise
-                result = e.returncode
-                log("Couldn't acquire DPKG lock. Will retry in {} seconds."
-                    "".format(APT_NO_LOCK_RETRY_DELAY))
-                time.sleep(APT_NO_LOCK_RETRY_DELAY)
-
-    else:
-        subprocess.call(cmd, env=env)

=== modified file 'hooks/charmhelpers/fetch/archiveurl.py'
--- hooks/charmhelpers/fetch/archiveurl.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/fetch/archiveurl.py	2017-03-03 23:04:07 +0000
@@ -1,18 +1,16 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
 import hashlib
@@ -77,6 +75,8 @@
     def can_handle(self, source):
         url_parts = self.parse_url(source)
         if url_parts.scheme not in ('http', 'https', 'ftp', 'file'):
+            # XXX: Why is this returning a boolean and a string? It's
+            # doomed to fail since "bool(can_handle('foo://'))"  will be True.
             return "Wrong source type"
         if get_archive_handler(self.base_url(source)):
             return True
@@ -106,7 +106,7 @@
                 install_opener(opener)
         response = urlopen(source)
         try:
-            with open(dest, 'w') as dest_file:
+            with open(dest, 'wb') as dest_file:
                 dest_file.write(response.read())
         except Exception as e:
             if os.path.isfile(dest):
@@ -155,7 +155,11 @@
             else:
                 algorithms = hashlib.algorithms_available
             if key in algorithms:
-                check_hash(dld_file, value, key)
+                if len(value) != 1:
+                    raise TypeError(
+                        "Expected 1 hash value, not %d" % len(value))
+                expected = value[0]
+                check_hash(dld_file, expected, key)
         if checksum:
             check_hash(dld_file, checksum, hash_type)
         return extract(dld_file, dest)

=== modified file 'hooks/charmhelpers/fetch/bzrurl.py'
--- hooks/charmhelpers/fetch/bzrurl.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/fetch/bzrurl.py	2017-03-03 23:04:07 +0000
@@ -1,78 +1,76 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
+from subprocess import check_call
 from charmhelpers.fetch import (
     BaseFetchHandler,
-    UnhandledSource
+    UnhandledSource,
+    filter_installed_packages,
+    install,
 )
 from charmhelpers.core.host import mkdir
 
-import six
-if six.PY3:
-    raise ImportError('bzrlib does not support Python3')
 
-try:
-    from bzrlib.branch import Branch
-    from bzrlib import bzrdir, workingtree, errors
-except ImportError:
-    from charmhelpers.fetch import apt_install
-    apt_install("python-bzrlib")
-    from bzrlib.branch import Branch
-    from bzrlib import bzrdir, workingtree, errors
+if filter_installed_packages(['bzr']) != []:
+    install(['bzr'])
+    if filter_installed_packages(['bzr']) != []:
+        raise NotImplementedError('Unable to install bzr')
 
 
 class BzrUrlFetchHandler(BaseFetchHandler):
-    """Handler for bazaar branches via generic and lp URLs"""
+    """Handler for bazaar branches via generic and lp URLs."""
+
     def can_handle(self, source):
         url_parts = self.parse_url(source)
-        if url_parts.scheme not in ('bzr+ssh', 'lp'):
+        if url_parts.scheme not in ('bzr+ssh', 'lp', ''):
             return False
+        elif not url_parts.scheme:
+            return os.path.exists(os.path.join(source, '.bzr'))
         else:
             return True
 
-    def branch(self, source, dest):
-        url_parts = self.parse_url(source)
-        # If we use lp:branchname scheme we need to load plugins
+    def branch(self, source, dest, revno=None):
         if not self.can_handle(source):
             raise UnhandledSource("Cannot handle {}".format(source))
-        if url_parts.scheme == "lp":
-            from bzrlib.plugin import load_plugins
-            load_plugins()
-        try:
-            local_branch = bzrdir.BzrDir.create_branch_convenience(dest)
-        except errors.AlreadyControlDirError:
-            local_branch = Branch.open(dest)
-        try:
-            remote_branch = Branch.open(source)
-            remote_branch.push(local_branch)
-            tree = workingtree.WorkingTree.open(dest)
-            tree.update()
-        except Exception as e:
-            raise e
+        cmd_opts = []
+        if revno:
+            cmd_opts += ['-r', str(revno)]
+        if os.path.exists(dest):
+            cmd = ['bzr', 'pull']
+            cmd += cmd_opts
+            cmd += ['--overwrite', '-d', dest, source]
+        else:
+            cmd = ['bzr', 'branch']
+            cmd += cmd_opts
+            cmd += [source, dest]
+        check_call(cmd)
 
-    def install(self, source):
+    def install(self, source, dest=None, revno=None):
         url_parts = self.parse_url(source)
         branch_name = url_parts.path.strip("/").split("/")[-1]
-        dest_dir = os.path.join(os.environ.get('CHARM_DIR'), "fetched",
-                                branch_name)
-        if not os.path.exists(dest_dir):
-            mkdir(dest_dir, perms=0o755)
+        if dest:
+            dest_dir = os.path.join(dest, branch_name)
+        else:
+            dest_dir = os.path.join(os.environ.get('CHARM_DIR'), "fetched",
+                                    branch_name)
+
+        if dest and not os.path.exists(dest):
+            mkdir(dest, perms=0o755)
+
         try:
-            self.branch(source, dest_dir)
+            self.branch(source, dest_dir, revno)
         except OSError as e:
             raise UnhandledSource(e.strerror)
         return dest_dir

=== added file 'hooks/charmhelpers/fetch/centos.py'
--- hooks/charmhelpers/fetch/centos.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/fetch/centos.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,171 @@
+# Copyright 2014-2015 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import subprocess
+import os
+import time
+import six
+import yum
+
+from tempfile import NamedTemporaryFile
+from charmhelpers.core.hookenv import log
+
+YUM_NO_LOCK = 1  # The return code for "couldn't acquire lock" in YUM.
+YUM_NO_LOCK_RETRY_DELAY = 10  # Wait 10 seconds between apt lock checks.
+YUM_NO_LOCK_RETRY_COUNT = 30  # Retry to acquire the lock X times.
+
+
+def filter_installed_packages(packages):
+    """Return a list of packages that require installation."""
+    yb = yum.YumBase()
+    package_list = yb.doPackageLists()
+    temp_cache = {p.base_package_name: 1 for p in package_list['installed']}
+
+    _pkgs = [p for p in packages if not temp_cache.get(p, False)]
+    return _pkgs
+
+
+def install(packages, options=None, fatal=False):
+    """Install one or more packages."""
+    cmd = ['yum', '--assumeyes']
+    if options is not None:
+        cmd.extend(options)
+    cmd.append('install')
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+    log("Installing {} with options: {}".format(packages,
+                                                options))
+    _run_yum_command(cmd, fatal)
+
+
+def upgrade(options=None, fatal=False, dist=False):
+    """Upgrade all packages."""
+    cmd = ['yum', '--assumeyes']
+    if options is not None:
+        cmd.extend(options)
+    cmd.append('upgrade')
+    log("Upgrading with options: {}".format(options))
+    _run_yum_command(cmd, fatal)
+
+
+def update(fatal=False):
+    """Update local yum cache."""
+    cmd = ['yum', '--assumeyes', 'update']
+    log("Update with fatal: {}".format(fatal))
+    _run_yum_command(cmd, fatal)
+
+
+def purge(packages, fatal=False):
+    """Purge one or more packages."""
+    cmd = ['yum', '--assumeyes', 'remove']
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+    log("Purging {}".format(packages))
+    _run_yum_command(cmd, fatal)
+
+
+def yum_search(packages):
+    """Search for a package."""
+    output = {}
+    cmd = ['yum', 'search']
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+    log("Searching for {}".format(packages))
+    result = subprocess.check_output(cmd)
+    for package in list(packages):
+        output[package] = package in result
+    return output
+
+
+def add_source(source, key=None):
+    """Add a package source to this system.
+
+    @param source: a URL with a rpm package
+
+    @param key: A key to be added to the system's keyring and used
+    to verify the signatures on packages. Ideally, this should be an
+    ASCII format GPG public key including the block headers. A GPG key
+    id may also be used, but be aware that only insecure protocols are
+    available to retrieve the actual public key from a public keyserver
+    placing your Juju environment at risk.
+    """
+    if source is None:
+        log('Source is not present. Skipping')
+        return
+
+    if source.startswith('http'):
+        directory = '/etc/yum.repos.d/'
+        for filename in os.listdir(directory):
+            with open(directory + filename, 'r') as rpm_file:
+                if source in rpm_file.read():
+                    break
+        else:
+            log("Add source: {!r}".format(source))
+            # write in the charms.repo
+            with open(directory + 'Charms.repo', 'a') as rpm_file:
+                rpm_file.write('[%s]\n' % source[7:].replace('/', '_'))
+                rpm_file.write('name=%s\n' % source[7:])
+                rpm_file.write('baseurl=%s\n\n' % source)
+    else:
+        log("Unknown source: {!r}".format(source))
+
+    if key:
+        if '-----BEGIN PGP PUBLIC KEY BLOCK-----' in key:
+            with NamedTemporaryFile('w+') as key_file:
+                key_file.write(key)
+                key_file.flush()
+                key_file.seek(0)
+            subprocess.check_call(['rpm', '--import', key_file])
+        else:
+            subprocess.check_call(['rpm', '--import', key])
+
+
+def _run_yum_command(cmd, fatal=False):
+    """Run an YUM command.
+
+    Checks the output and retry if the fatal flag is set to True.
+
+    :param: cmd: str: The yum command to run.
+    :param: fatal: bool: Whether the command's output should be checked and
+        retried.
+    """
+    env = os.environ.copy()
+
+    if fatal:
+        retry_count = 0
+        result = None
+
+        # If the command is considered "fatal", we need to retry if the yum
+        # lock was not acquired.
+
+        while result is None or result == YUM_NO_LOCK:
+            try:
+                result = subprocess.check_call(cmd, env=env)
+            except subprocess.CalledProcessError as e:
+                retry_count = retry_count + 1
+                if retry_count > YUM_NO_LOCK_RETRY_COUNT:
+                    raise
+                result = e.returncode
+                log("Couldn't acquire YUM lock. Will retry in {} seconds."
+                    "".format(YUM_NO_LOCK_RETRY_DELAY))
+                time.sleep(YUM_NO_LOCK_RETRY_DELAY)
+
+    else:
+        subprocess.call(cmd, env=env)

=== modified file 'hooks/charmhelpers/fetch/giturl.py'
--- hooks/charmhelpers/fetch/giturl.py	2015-05-25 19:04:56 +0000
+++ hooks/charmhelpers/fetch/giturl.py	2017-03-03 23:04:07 +0000
@@ -1,58 +1,58 @@
 # Copyright 2014-2015 Canonical Limited.
 #
-# This file is part of charm-helpers.
-#
-# charm-helpers is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Lesser General Public License version 3 as
-# published by the Free Software Foundation.
-#
-# charm-helpers is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 import os
+from subprocess import check_call, CalledProcessError
 from charmhelpers.fetch import (
     BaseFetchHandler,
-    UnhandledSource
+    UnhandledSource,
+    filter_installed_packages,
+    install,
 )
-from charmhelpers.core.host import mkdir
-
-import six
-if six.PY3:
-    raise ImportError('GitPython does not support Python 3')
-
-try:
-    from git import Repo
-except ImportError:
-    from charmhelpers.fetch import apt_install
-    apt_install("python-git")
-    from git import Repo
-
-from git.exc import GitCommandError  # noqa E402
+
+if filter_installed_packages(['git']) != []:
+    install(['git'])
+    if filter_installed_packages(['git']) != []:
+        raise NotImplementedError('Unable to install git')
 
 
 class GitUrlFetchHandler(BaseFetchHandler):
-    """Handler for git branches via generic and github URLs"""
+    """Handler for git branches via generic and github URLs."""
+
     def can_handle(self, source):
         url_parts = self.parse_url(source)
         # TODO (mattyw) no support for ssh git@ yet
-        if url_parts.scheme not in ('http', 'https', 'git'):
+        if url_parts.scheme not in ('http', 'https', 'git', ''):
             return False
+        elif not url_parts.scheme:
+            return os.path.exists(os.path.join(source, '.git'))
         else:
             return True
 
-    def clone(self, source, dest, branch):
+    def clone(self, source, dest, branch="master", depth=None):
         if not self.can_handle(source):
             raise UnhandledSource("Cannot handle {}".format(source))
 
-        repo = Repo.clone_from(source, dest)
-        repo.git.checkout(branch)
+        if os.path.exists(dest):
+            cmd = ['git', '-C', dest, 'pull', source, branch]
+        else:
+            cmd = ['git', 'clone', source, dest, '--branch', branch]
+            if depth:
+                cmd.extend(['--depth', depth])
+        check_call(cmd)
 
-    def install(self, source, branch="master", dest=None):
+    def install(self, source, branch="master", dest=None, depth=None):
         url_parts = self.parse_url(source)
         branch_name = url_parts.path.strip("/").split("/")[-1]
         if dest:
@@ -60,12 +60,10 @@
         else:
             dest_dir = os.path.join(os.environ.get('CHARM_DIR'), "fetched",
                                     branch_name)
-        if not os.path.exists(dest_dir):
-            mkdir(dest_dir, perms=0o755)
         try:
-            self.clone(source, dest_dir, branch)
-        except GitCommandError as e:
-            raise UnhandledSource(e.message)
+            self.clone(source, dest_dir, branch, depth)
+        except CalledProcessError as e:
+            raise UnhandledSource(e)
         except OSError as e:
             raise UnhandledSource(e.strerror)
         return dest_dir

=== added file 'hooks/charmhelpers/fetch/snap.py'
--- hooks/charmhelpers/fetch/snap.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/fetch/snap.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,122 @@
+# Copyright 2014-2017 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Charm helpers snap for classic charms.
+
+If writing reactive charms, use the snap layer:
+https://lists.ubuntu.com/archives/snapcraft/2016-September/001114.html
+"""
+import subprocess
+from os import environ
+from time import sleep
+from charmhelpers.core.hookenv import log
+
+__author__ = 'Joseph Borg <[e-mail]>'
+
+SNAP_NO_LOCK = 1  # The return code for "couldn't acquire lock" in Snap (hopefully this will be improved).
+SNAP_NO_LOCK_RETRY_DELAY = 10  # Wait X seconds between Snap lock checks.
+SNAP_NO_LOCK_RETRY_COUNT = 30  # Retry to acquire the lock X times.
+
+
+class CouldNotAcquireLockException(Exception):
+    pass
+
+
+def _snap_exec(commands):
+    """
+    Execute snap commands.
+
+    :param commands: List commands
+    :return: Integer exit code
+    """
+    assert type(commands) == list
+
+    retry_count = 0
+    return_code = None
+
+    while return_code is None or return_code == SNAP_NO_LOCK:
+        try:
+            return_code = subprocess.check_call(['snap'] + commands, env=environ)
+        except subprocess.CalledProcessError as e:
+            retry_count += + 1
+            if retry_count > SNAP_NO_LOCK_RETRY_COUNT:
+                raise CouldNotAcquireLockException('Could not aquire lock after %s attempts' % SNAP_NO_LOCK_RETRY_COUNT)
+            return_code = e.returncode
+            log('Snap failed to acquire lock, trying again in %s seconds.' % SNAP_NO_LOCK_RETRY_DELAY, level='WARN')
+            sleep(SNAP_NO_LOCK_RETRY_DELAY)
+
+    return return_code
+
+
+def snap_install(packages, *flags):
+    """
+    Install a snap package.
+
+    :param packages: String or List String package name
+    :param flags: List String flags to pass to install command
+    :return: Integer return code from snap
+    """
+    if type(packages) is not list:
+        packages = [packages]
+
+    flags = list(flags)
+
+    message = 'Installing snap(s) "%s"' % ', '.join(packages)
+    if flags:
+        message += ' with option(s) "%s"' % ', '.join(flags)
+
+    log(message, level='INFO')
+    return _snap_exec(['install'] + flags + packages)
+
+
+def snap_remove(packages, *flags):
+    """
+    Remove a snap package.
+
+    :param packages: String or List String package name
+    :param flags: List String flags to pass to remove command
+    :return: Integer return code from snap
+    """
+    if type(packages) is not list:
+        packages = [packages]
+
+    flags = list(flags)
+
+    message = 'Removing snap(s) "%s"' % ', '.join(packages)
+    if flags:
+        message += ' with options "%s"' % ', '.join(flags)
+
+    log(message, level='INFO')
+    return _snap_exec(['remove'] + flags + packages)
+
+
+def snap_refresh(packages, *flags):
+    """
+    Refresh / Update snap package.
+
+    :param packages: String or List String package name
+    :param flags: List String flags to pass to refresh command
+    :return: Integer return code from snap
+    """
+    if type(packages) is not list:
+        packages = [packages]
+
+    flags = list(flags)
+
+    message = 'Refreshing snap(s) "%s"' % ', '.join(packages)
+    if flags:
+        message += ' with options "%s"' % ', '.join(flags)
+
+    log(message, level='INFO')
+    return _snap_exec(['refresh'] + flags + packages)

=== added file 'hooks/charmhelpers/fetch/ubuntu.py'
--- hooks/charmhelpers/fetch/ubuntu.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/fetch/ubuntu.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,364 @@
+# Copyright 2014-2015 Canonical Limited.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import six
+import time
+import subprocess
+
+from tempfile import NamedTemporaryFile
+from charmhelpers.core.host import (
+    lsb_release
+)
+from charmhelpers.core.hookenv import log
+from charmhelpers.fetch import SourceConfigError
+
+CLOUD_ARCHIVE = """# Ubuntu Cloud Archive
+deb http://ubuntu-cloud.archive.canonical.com/ubuntu {} main
+"""
+
+PROPOSED_POCKET = """# Proposed
+deb http://archive.ubuntu.com/ubuntu {}-proposed main universe multiverse restricted
+"""
+
+CLOUD_ARCHIVE_POCKETS = {
+    # Folsom
+    'folsom': 'precise-updates/folsom',
+    'precise-folsom': 'precise-updates/folsom',
+    'precise-folsom/updates': 'precise-updates/folsom',
+    'precise-updates/folsom': 'precise-updates/folsom',
+    'folsom/proposed': 'precise-proposed/folsom',
+    'precise-folsom/proposed': 'precise-proposed/folsom',
+    'precise-proposed/folsom': 'precise-proposed/folsom',
+    # Grizzly
+    'grizzly': 'precise-updates/grizzly',
+    'precise-grizzly': 'precise-updates/grizzly',
+    'precise-grizzly/updates': 'precise-updates/grizzly',
+    'precise-updates/grizzly': 'precise-updates/grizzly',
+    'grizzly/proposed': 'precise-proposed/grizzly',
+    'precise-grizzly/proposed': 'precise-proposed/grizzly',
+    'precise-proposed/grizzly': 'precise-proposed/grizzly',
+    # Havana
+    'havana': 'precise-updates/havana',
+    'precise-havana': 'precise-updates/havana',
+    'precise-havana/updates': 'precise-updates/havana',
+    'precise-updates/havana': 'precise-updates/havana',
+    'havana/proposed': 'precise-proposed/havana',
+    'precise-havana/proposed': 'precise-proposed/havana',
+    'precise-proposed/havana': 'precise-proposed/havana',
+    # Icehouse
+    'icehouse': 'precise-updates/icehouse',
+    'precise-icehouse': 'precise-updates/icehouse',
+    'precise-icehouse/updates': 'precise-updates/icehouse',
+    'precise-updates/icehouse': 'precise-updates/icehouse',
+    'icehouse/proposed': 'precise-proposed/icehouse',
+    'precise-icehouse/proposed': 'precise-proposed/icehouse',
+    'precise-proposed/icehouse': 'precise-proposed/icehouse',
+    # Juno
+    'juno': 'trusty-updates/juno',
+    'trusty-juno': 'trusty-updates/juno',
+    'trusty-juno/updates': 'trusty-updates/juno',
+    'trusty-updates/juno': 'trusty-updates/juno',
+    'juno/proposed': 'trusty-proposed/juno',
+    'trusty-juno/proposed': 'trusty-proposed/juno',
+    'trusty-proposed/juno': 'trusty-proposed/juno',
+    # Kilo
+    'kilo': 'trusty-updates/kilo',
+    'trusty-kilo': 'trusty-updates/kilo',
+    'trusty-kilo/updates': 'trusty-updates/kilo',
+    'trusty-updates/kilo': 'trusty-updates/kilo',
+    'kilo/proposed': 'trusty-proposed/kilo',
+    'trusty-kilo/proposed': 'trusty-proposed/kilo',
+    'trusty-proposed/kilo': 'trusty-proposed/kilo',
+    # Liberty
+    'liberty': 'trusty-updates/liberty',
+    'trusty-liberty': 'trusty-updates/liberty',
+    'trusty-liberty/updates': 'trusty-updates/liberty',
+    'trusty-updates/liberty': 'trusty-updates/liberty',
+    'liberty/proposed': 'trusty-proposed/liberty',
+    'trusty-liberty/proposed': 'trusty-proposed/liberty',
+    'trusty-proposed/liberty': 'trusty-proposed/liberty',
+    # Mitaka
+    'mitaka': 'trusty-updates/mitaka',
+    'trusty-mitaka': 'trusty-updates/mitaka',
+    'trusty-mitaka/updates': 'trusty-updates/mitaka',
+    'trusty-updates/mitaka': 'trusty-updates/mitaka',
+    'mitaka/proposed': 'trusty-proposed/mitaka',
+    'trusty-mitaka/proposed': 'trusty-proposed/mitaka',
+    'trusty-proposed/mitaka': 'trusty-proposed/mitaka',
+    # Newton
+    'newton': 'xenial-updates/newton',
+    'xenial-newton': 'xenial-updates/newton',
+    'xenial-newton/updates': 'xenial-updates/newton',
+    'xenial-updates/newton': 'xenial-updates/newton',
+    'newton/proposed': 'xenial-proposed/newton',
+    'xenial-newton/proposed': 'xenial-proposed/newton',
+    'xenial-proposed/newton': 'xenial-proposed/newton',
+    # Ocata
+    'ocata': 'xenial-updates/ocata',
+    'xenial-ocata': 'xenial-updates/ocata',
+    'xenial-ocata/updates': 'xenial-updates/ocata',
+    'xenial-updates/ocata': 'xenial-updates/ocata',
+    'ocata/proposed': 'xenial-proposed/ocata',
+    'xenial-ocata/proposed': 'xenial-proposed/ocata',
+    'xenial-ocata/newton': 'xenial-proposed/ocata',
+}
+
+APT_NO_LOCK = 100  # The return code for "couldn't acquire lock" in APT.
+CMD_RETRY_DELAY = 10  # Wait 10 seconds between command retries.
+CMD_RETRY_COUNT = 30  # Retry a failing fatal command X times.
+
+
+def filter_installed_packages(packages):
+    """Return a list of packages that require installation."""
+    cache = apt_cache()
+    _pkgs = []
+    for package in packages:
+        try:
+            p = cache[package]
+            p.current_ver or _pkgs.append(package)
+        except KeyError:
+            log('Package {} has no installation candidate.'.format(package),
+                level='WARNING')
+            _pkgs.append(package)
+    return _pkgs
+
+
+def apt_cache(in_memory=True, progress=None):
+    """Build and return an apt cache."""
+    from apt import apt_pkg
+    apt_pkg.init()
+    if in_memory:
+        apt_pkg.config.set("Dir::Cache::pkgcache", "")
+        apt_pkg.config.set("Dir::Cache::srcpkgcache", "")
+    return apt_pkg.Cache(progress)
+
+
+def install(packages, options=None, fatal=False):
+    """Install one or more packages."""
+    if options is None:
+        options = ['--option=Dpkg::Options::=--force-confold']
+
+    cmd = ['apt-get', '--assume-yes']
+    cmd.extend(options)
+    cmd.append('install')
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+    log("Installing {} with options: {}".format(packages,
+                                                options))
+    _run_apt_command(cmd, fatal)
+
+
+def upgrade(options=None, fatal=False, dist=False):
+    """Upgrade all packages."""
+    if options is None:
+        options = ['--option=Dpkg::Options::=--force-confold']
+
+    cmd = ['apt-get', '--assume-yes']
+    cmd.extend(options)
+    if dist:
+        cmd.append('dist-upgrade')
+    else:
+        cmd.append('upgrade')
+    log("Upgrading with options: {}".format(options))
+    _run_apt_command(cmd, fatal)
+
+
+def update(fatal=False):
+    """Update local apt cache."""
+    cmd = ['apt-get', 'update']
+    _run_apt_command(cmd, fatal)
+
+
+def purge(packages, fatal=False):
+    """Purge one or more packages."""
+    cmd = ['apt-get', '--assume-yes', 'purge']
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+    log("Purging {}".format(packages))
+    _run_apt_command(cmd, fatal)
+
+
+def apt_mark(packages, mark, fatal=False):
+    """Flag one or more packages using apt-mark."""
+    log("Marking {} as {}".format(packages, mark))
+    cmd = ['apt-mark', mark]
+    if isinstance(packages, six.string_types):
+        cmd.append(packages)
+    else:
+        cmd.extend(packages)
+
+    if fatal:
+        subprocess.check_call(cmd, universal_newlines=True)
+    else:
+        subprocess.call(cmd, universal_newlines=True)
+
+
+def apt_hold(packages, fatal=False):
+    return apt_mark(packages, 'hold', fatal=fatal)
+
+
+def apt_unhold(packages, fatal=False):
+    return apt_mark(packages, 'unhold', fatal=fatal)
+
+
+def add_source(source, key=None):
+    """Add a package source to this system.
+
+    @param source: a URL or sources.list entry, as supported by
+    add-apt-repository(1). Examples::
+
+        ppa:charmers/example
+        deb https://stub:[e-mail]/ubuntu trusty main
+
+    In addition:
+        'proposed:' may be used to enable the standard 'proposed'
+        pocket for the release.
+        'cloud:' may be used to activate official cloud archive pockets,
+        such as 'cloud:icehouse'
+        'distro' may be used as a noop
+
+    @param key: A key to be added to the system's APT keyring and used
+    to verify the signatures on packages. Ideally, this should be an
+    ASCII format GPG public key including the block headers. A GPG key
+    id may also be used, but be aware that only insecure protocols are
+    available to retrieve the actual public key from a public keyserver
+    placing your Juju environment at risk. ppa and cloud archive keys
+    are securely added automtically, so sould not be provided.
+    """
+    if source is None:
+        log('Source is not present. Skipping')
+        return
+
+    if (source.startswith('ppa:') or
+        source.startswith('http') or
+        source.startswith('deb ') or
+            source.startswith('cloud-archive:')):
+        cmd = ['add-apt-repository', '--yes', source]
+        _run_with_retries(cmd)
+    elif source.startswith('cloud:'):
+        install(filter_installed_packages(['ubuntu-cloud-keyring']),
+                fatal=True)
+        pocket = source.split(':')[-1]
+        if pocket not in CLOUD_ARCHIVE_POCKETS:
+            raise SourceConfigError(
+                'Unsupported cloud: source option %s' %
+                pocket)
+        actual_pocket = CLOUD_ARCHIVE_POCKETS[pocket]
+        with open('/etc/apt/sources.list.d/cloud-archive.list', 'w') as apt:
+            apt.write(CLOUD_ARCHIVE.format(actual_pocket))
+    elif source == 'proposed':
+        release = lsb_release()['DISTRIB_CODENAME']
+        with open('/etc/apt/sources.list.d/proposed.list', 'w') as apt:
+            apt.write(PROPOSED_POCKET.format(release))
+    elif source == 'distro':
+        pass
+    else:
+        log("Unknown source: {!r}".format(source))
+
+    if key:
+        if '-----BEGIN PGP PUBLIC KEY BLOCK-----' in key:
+            with NamedTemporaryFile('w+') as key_file:
+                key_file.write(key)
+                key_file.flush()
+                key_file.seek(0)
+                subprocess.check_call(['apt-key', 'add', '-'], stdin=key_file)
+        else:
+            # Note that hkp: is in no way a secure protocol. Using a
+            # GPG key id is pointless from a security POV unless you
+            # absolutely trust your network and DNS.
+            subprocess.check_call(['apt-key', 'adv', '--keyserver',
+                                   'hkp://keyserver.ubuntu.com:80', '--recv',
+                                   key])
+
+
+def _run_with_retries(cmd, max_retries=CMD_RETRY_COUNT, retry_exitcodes=(1,),
+                      retry_message="", cmd_env=None):
+    """Run a command and retry until success or max_retries is reached.
+
+    :param: cmd: str: The apt command to run.
+    :param: max_retries: int: The number of retries to attempt on a fatal
+        command. Defaults to CMD_RETRY_COUNT.
+    :param: retry_exitcodes: tuple: Optional additional exit codes to retry.
+        Defaults to retry on exit code 1.
+    :param: retry_message: str: Optional log prefix emitted during retries.
+    :param: cmd_env: dict: Environment variables to add to the command run.
+    """
+
+    env = os.environ.copy()
+    if cmd_env:
+        env.update(cmd_env)
+
+    if not retry_message:
+        retry_message = "Failed executing '{}'".format(" ".join(cmd))
+    retry_message += ". Will retry in {} seconds".format(CMD_RETRY_DELAY)
+
+    retry_count = 0
+    result = None
+
+    retry_results = (None,) + retry_exitcodes
+    while result in retry_results:
+        try:
+            result = subprocess.check_call(cmd, env=env)
+        except subprocess.CalledProcessError as e:
+            retry_count = retry_count + 1
+            if retry_count > max_retries:
+                raise
+            result = e.returncode
+            log(retry_message)
+            time.sleep(CMD_RETRY_DELAY)
+
+
+def _run_apt_command(cmd, fatal=False):
+    """Run an apt command with optional retries.
+
+    :param: fatal: bool: Whether the command's output should be checked and
+        retried.
+    """
+    # Provide DEBIAN_FRONTEND=noninteractive if not present in the environment.
+    cmd_env = {
+        'DEBIAN_FRONTEND': os.environ.get('DEBIAN_FRONTEND', 'noninteractive')}
+
+    if fatal:
+        _run_with_retries(
+            cmd, cmd_env=cmd_env, retry_exitcodes=(1, APT_NO_LOCK,),
+            retry_message="Couldn't acquire DPKG lock")
+    else:
+        env = os.environ.copy()
+        env.update(cmd_env)
+        subprocess.call(cmd, env=env)
+
+
+def get_upstream_version(package):
+    """Determine upstream version based on installed package
+
+    @returns None (if not installed) or the upstream version
+    """
+    import apt_pkg
+    cache = apt_cache()
+    try:
+        pkg = cache[package]
+    except:
+        # the package is unknown to the current apt cache.
+        return None
+
+    if not pkg.current_ver:
+        # package is known, but no version is currently installed.
+        return None
+
+    return apt_pkg.upstream_version(pkg.current_ver.ver_str)

=== added file 'hooks/charmhelpers/osplatform.py'
--- hooks/charmhelpers/osplatform.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/osplatform.py	2017-03-03 23:04:07 +0000
@@ -0,0 +1,25 @@
+import platform
+
+
+def get_platform():
+    """Return the current OS platform.
+
+    For example: if current os platform is Ubuntu then a string "ubuntu"
+    will be returned (which is the name of the module).
+    This string is used to decide which platform module should be imported.
+    """
+    # linux_distribution is deprecated and will be removed in Python 3.7
+    # Warings *not* disabled, as we certainly need to fix this.
+    tuple_platform = platform.linux_distribution()
+    current_platform = tuple_platform[0]
+    if "Ubuntu" in current_platform:
+        return "ubuntu"
+    elif "CentOS" in current_platform:
+        return "centos"
+    elif "debian" in current_platform:
+        # Stock Python does not detect Ubuntu and instead returns debian.
+        # Or at least it does in some build environments like Travis CI
+        return "ubuntu"
+    else:
+        raise RuntimeError("This module is not supported on {}."
+                           .format(current_platform))

=== modified file 'hooks/install.py'
--- hooks/install.py	2016-05-26 08:23:07 +0000
+++ hooks/install.py	2017-03-03 23:04:07 +0000
@@ -14,7 +14,9 @@
 from charmhelpers.core.hookenv import (
     Hooks, UnregisteredHookError, log)
 from charmhelpers.fetch import (
-    apt_install, _run_apt_command, add_source, apt_update)
+    apt_install, add_source, apt_update)
+# TODO fix charhelpers to expose this retry command logic somewhere nice.
+from charmhelpers.fetch.ubuntu import (_run_apt_command)
 from charmhelpers.core.hookenv import config
 
 
@@ -60,7 +62,7 @@
     # acquire the dpkg lock).
     subprocess.call(["dpkg", "-i", glob("../landscape-client_*.deb")[0],
                      glob("../landscape-common_*.deb")[0]])
-    # The _run_apt_command will ensure the command is retried in case we cannot
+    # The _run_with_retries will ensure the command is retried in case we can't
     # acquire the lock for some reason.
     _run_apt_command(["apt-get", "-f", "install"], fatal=True)
     os.chdir("..")