Merge lp:~timkuhlman/charms/trusty/rsyslog-forwarder-ha/nrpe into lp:charms/trusty/rsyslog-forwarder-ha

[Tim Kuhlman]

Adds an nrpe relation and nagios check for the rsyslog daemon.

[lp:~timkuhlman/charms/trusty/rsyslog-forwarder-ha/nrpe]

15. By Tim Kuhlman on 2016-04-28

Make tcp failover mode more robust especially on Juju controllers

[Junien Fridrick (axino)]

Perhaps the added "$ActionQueueDiscardSeverity" could be a charm option ?

[lp:~timkuhlman/charms/trusty/rsyslog-forwarder-ha/nrpe]

16. By Tim Kuhlman on 2016-05-02

The default config logs locally so that even with log-locally set false that was happening. Fixed it so that log-locally overwrites the default config

17. By Tim Kuhlman on 2016-05-02

Restore a working default config on stop

18. By Tim Kuhlman on 2016-05-03

Set $ActionSendStreamDriver rather than resetting the default which breaks anything relying on the previous default

[Review Queue (review-queue)]

This item has failed automated testing! Results available here http://juju-ci.vapour.ws:8080/job/charm-bundle-test-aws/3949/

review: Needs Fixing (automated testing)

[Review Queue (review-queue)]

This item has failed automated testing! Results available here http://juju-ci.vapour.ws:8080/job/charm-bundle-test-aws/3950/

review: Needs Fixing (automated testing)

[lp:~timkuhlman/charms/trusty/rsyslog-forwarder-ha/nrpe]

19. By Tim Kuhlman on 2016-05-04

Explicitly set tcp mode to non-ssl

[Review Queue (review-queue)]

This item has failed automated testing! Results available here http://juju-ci.vapour.ws:8080/job/charm-bundle-test-lxc/3904/

review: Needs Fixing (automated testing)

[Review Queue (review-queue)]

This item has failed automated testing! Results available here http://juju-ci.vapour.ws:8080/job/charm-bundle-test-lxc/3905/

review: Needs Fixing (automated testing)

[Adam Israel (aisrael)]

Hey Tim,

Since the current CI/review queue only keeps logs of the last 300 runs (which will be fixed in the new RQ), here's the output of my tests running against AWS and Juju 2 beta 7.

http://pastebin.ubuntu.com/16508154/

review: Needs Fixing

[lp:~timkuhlman/charms/trusty/rsyslog-forwarder-ha/nrpe]

20. By Tim Kuhlman on 2016-05-19

Lint fixes and fix for stop test

[Tim Kuhlman (timkuhlman)]

Thanks I just pushed up the fixes.

On 05/19/2016 09:37 AM, Adam Israel wrote:
> Review: Needs Fixing
>
> Hey Tim,
>
> Since the current CI/review queue only keeps logs of the last 300 runs (which will be fixed in the new RQ), here's the output of my tests running against AWS and Juju 2 beta 7.
>
> http://pastebin.ubuntu.com/16508154/
>

--
Tim Kuhlman
CDO - IS - Foxtrot

[Andrew McLeod (admcleod)]

All tests passing, bundletester all OK, +1

review: Approve

[Stuart Bishop (stub)]

Looks good

review: Approve

=== modified file 'charm-helpers.yaml'
--- charm-helpers.yaml	2014-04-25 22:18:46 +0000
+++ charm-helpers.yaml	2016-05-19 16:36:23 +0000
@@ -3,3 +3,4 @@
 include:
   - core
   - fetch
+  - contrib.charmsupport

=== modified file 'config.yaml'
--- config.yaml	2016-03-30 21:54:14 +0000
+++ config.yaml	2016-05-19 16:36:23 +0000
@@ -7,6 +7,22 @@
     type: string
     default: fanout
     description: Possible options are 'fanout' or 'failover' fanout replicates the log messages over all the defined syslog relations, failover replicates the log messages just if the previous server is down. Failover always uses tcp for the protocol.
+  nagios_context:
+    default: "juju"
+    type: string
+    description: >
+        Used by the nrpe-external-master subordinate charm.
+        A string that will be prepended to instance name to set the host name
+        in nagios. So for instance the hostname would be something like:
+            juju-rsyslog-forwarder-ha-0
+        If you're running multiple environments with the same services in them
+        this allows you to differentiate between them.
+  nagios_servicegroups:
+    default: ""
+    type: string
+    description: >
+        A comma-separated list of nagios servicegroups.
+        If left empty, the nagios_context will be used as the servicegroup
   protocol:
     type: string
     default: "udp"

=== added directory 'hooks/charmhelpers/contrib'
=== added file 'hooks/charmhelpers/contrib/__init__.py'
=== added directory 'hooks/charmhelpers/contrib/charmsupport'
=== added file 'hooks/charmhelpers/contrib/charmsupport/__init__.py'
--- hooks/charmhelpers/contrib/charmsupport/__init__.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/contrib/charmsupport/__init__.py	2016-05-19 16:36:23 +0000
@@ -0,0 +1,15 @@
+# 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/>.

=== added file 'hooks/charmhelpers/contrib/charmsupport/nrpe.py'
--- hooks/charmhelpers/contrib/charmsupport/nrpe.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/contrib/charmsupport/nrpe.py	2016-05-19 16:36:23 +0000
@@ -0,0 +1,398 @@
+# 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/>.
+
+"""Compatibility with the nrpe-external-master charm"""
+# Copyright 2012 Canonical Ltd.
+#
+# Authors:
+#  Matthew Wedgwood <[e-mail]>
+
+import subprocess
+import pwd
+import grp
+import os
+import glob
+import shutil
+import re
+import shlex
+import yaml
+
+from charmhelpers.core.hookenv import (
+    config,
+    local_unit,
+    log,
+    relation_ids,
+    relation_set,
+    relations_of_type,
+)
+
+from charmhelpers.core.host import service
+
+# This module adds compatibility with the nrpe-external-master and plain nrpe
+# subordinate charms. To use it in your charm:
+#
+# 1. Update metadata.yaml
+#
+#   provides:
+#     (...)
+#     nrpe-external-master:
+#       interface: nrpe-external-master
+#       scope: container
+#
+#   and/or
+#
+#   provides:
+#     (...)
+#     local-monitors:
+#       interface: local-monitors
+#       scope: container
+
+#
+# 2. Add the following to config.yaml
+#
+#    nagios_context:
+#      default: "juju"
+#      type: string
+#      description: |
+#        Used by the nrpe subordinate charms.
+#        A string that will be prepended to instance name to set the host name
+#        in nagios. So for instance the hostname would be something like:
+#            juju-myservice-0
+#        If you're running multiple environments with the same services in them
+#        this allows you to differentiate between them.
+#    nagios_servicegroups:
+#      default: ""
+#      type: string
+#      description: |
+#        A comma-separated list of nagios servicegroups.
+#        If left empty, the nagios_context will be used as the servicegroup
+#
+# 3. Add custom checks (Nagios plugins) to files/nrpe-external-master
+#
+# 4. Update your hooks.py with something like this:
+#
+#    from charmsupport.nrpe import NRPE
+#    (...)
+#    def update_nrpe_config():
+#        nrpe_compat = NRPE()
+#        nrpe_compat.add_check(
+#            shortname = "myservice",
+#            description = "Check MyService",
+#            check_cmd = "check_http -w 2 -c 10 http://localhost"
+#            )
+#        nrpe_compat.add_check(
+#            "myservice_other",
+#            "Check for widget failures",
+#            check_cmd = "/srv/myapp/scripts/widget_check"
+#            )
+#        nrpe_compat.write()
+#
+#    def config_changed():
+#        (...)
+#        update_nrpe_config()
+#
+#    def nrpe_external_master_relation_changed():
+#        update_nrpe_config()
+#
+#    def local_monitors_relation_changed():
+#        update_nrpe_config()
+#
+# 5. ln -s hooks.py nrpe-external-master-relation-changed
+#    ln -s hooks.py local-monitors-relation-changed
+
+
+class CheckException(Exception):
+    pass
+
+
+class Check(object):
+    shortname_re = '[A-Za-z0-9-_]+$'
+    service_template = ("""
+#---------------------------------------------------
+# This file is Juju managed
+#---------------------------------------------------
+define service {{
+    use                             active-service
+    host_name                       {nagios_hostname}
+    service_description             {nagios_hostname}[{shortname}] """
+                        """{description}
+    check_command                   check_nrpe!{command}
+    servicegroups                   {nagios_servicegroup}
+}}
+""")
+
+    def __init__(self, shortname, description, check_cmd):
+        super(Check, self).__init__()
+        # XXX: could be better to calculate this from the service name
+        if not re.match(self.shortname_re, shortname):
+            raise CheckException("shortname must match {}".format(
+                Check.shortname_re))
+        self.shortname = shortname
+        self.command = "check_{}".format(shortname)
+        # Note: a set of invalid characters is defined by the
+        # Nagios server config
+        # The default is: illegal_object_name_chars=`~!$%^&*"|'<>?,()=
+        self.description = description
+        self.check_cmd = self._locate_cmd(check_cmd)
+
+    def _get_check_filename(self):
+        return os.path.join(NRPE.nrpe_confdir, '{}.cfg'.format(self.command))
+
+    def _get_service_filename(self, hostname):
+        return os.path.join(NRPE.nagios_exportdir,
+                            'service__{}_{}.cfg'.format(hostname, self.command))
+
+    def _locate_cmd(self, check_cmd):
+        search_path = (
+            '/usr/lib/nagios/plugins',
+            '/usr/local/lib/nagios/plugins',
+        )
+        parts = shlex.split(check_cmd)
+        for path in search_path:
+            if os.path.exists(os.path.join(path, parts[0])):
+                command = os.path.join(path, parts[0])
+                if len(parts) > 1:
+                    command += " " + " ".join(parts[1:])
+                return command
+        log('Check command not found: {}'.format(parts[0]))
+        return ''
+
+    def _remove_service_files(self):
+        if not os.path.exists(NRPE.nagios_exportdir):
+            return
+        for f in os.listdir(NRPE.nagios_exportdir):
+            if f.endswith('_{}.cfg'.format(self.command)):
+                os.remove(os.path.join(NRPE.nagios_exportdir, f))
+
+    def remove(self, hostname):
+        nrpe_check_file = self._get_check_filename()
+        if os.path.exists(nrpe_check_file):
+            os.remove(nrpe_check_file)
+        self._remove_service_files()
+
+    def write(self, nagios_context, hostname, nagios_servicegroups):
+        nrpe_check_file = self._get_check_filename()
+        with open(nrpe_check_file, 'w') as nrpe_check_config:
+            nrpe_check_config.write("# check {}\n".format(self.shortname))
+            nrpe_check_config.write("command[{}]={}\n".format(
+                self.command, self.check_cmd))
+
+        if not os.path.exists(NRPE.nagios_exportdir):
+            log('Not writing service config as {} is not accessible'.format(
+                NRPE.nagios_exportdir))
+        else:
+            self.write_service_config(nagios_context, hostname,
+                                      nagios_servicegroups)
+
+    def write_service_config(self, nagios_context, hostname,
+                             nagios_servicegroups):
+        self._remove_service_files()
+
+        templ_vars = {
+            'nagios_hostname': hostname,
+            'nagios_servicegroup': nagios_servicegroups,
+            'description': self.description,
+            'shortname': self.shortname,
+            'command': self.command,
+        }
+        nrpe_service_text = Check.service_template.format(**templ_vars)
+        nrpe_service_file = self._get_service_filename(hostname)
+        with open(nrpe_service_file, 'w') as nrpe_service_config:
+            nrpe_service_config.write(str(nrpe_service_text))
+
+    def run(self):
+        subprocess.call(self.check_cmd)
+
+
+class NRPE(object):
+    nagios_logdir = '/var/log/nagios'
+    nagios_exportdir = '/var/lib/nagios/export'
+    nrpe_confdir = '/etc/nagios/nrpe.d'
+
+    def __init__(self, hostname=None):
+        super(NRPE, self).__init__()
+        self.config = config()
+        self.nagios_context = self.config['nagios_context']
+        if 'nagios_servicegroups' in self.config and self.config['nagios_servicegroups']:
+            self.nagios_servicegroups = self.config['nagios_servicegroups']
+        else:
+            self.nagios_servicegroups = self.nagios_context
+        self.unit_name = local_unit().replace('/', '-')
+        if hostname:
+            self.hostname = hostname
+        else:
+            nagios_hostname = get_nagios_hostname()
+            if nagios_hostname:
+                self.hostname = nagios_hostname
+            else:
+                self.hostname = "{}-{}".format(self.nagios_context, self.unit_name)
+        self.checks = []
+
+    def add_check(self, *args, **kwargs):
+        self.checks.append(Check(*args, **kwargs))
+
+    def remove_check(self, *args, **kwargs):
+        if kwargs.get('shortname') is None:
+            raise ValueError('shortname of check must be specified')
+
+        # Use sensible defaults if they're not specified - these are not
+        # actually used during removal, but they're required for constructing
+        # the Check object; check_disk is chosen because it's part of the
+        # nagios-plugins-basic package.
+        if kwargs.get('check_cmd') is None:
+            kwargs['check_cmd'] = 'check_disk'
+        if kwargs.get('description') is None:
+            kwargs['description'] = ''
+
+        check = Check(*args, **kwargs)
+        check.remove(self.hostname)
+
+    def write(self):
+        try:
+            nagios_uid = pwd.getpwnam('nagios').pw_uid
+            nagios_gid = grp.getgrnam('nagios').gr_gid
+        except:
+            log("Nagios user not set up, nrpe checks not updated")
+            return
+
+        if not os.path.exists(NRPE.nagios_logdir):
+            os.mkdir(NRPE.nagios_logdir)
+            os.chown(NRPE.nagios_logdir, nagios_uid, nagios_gid)
+
+        nrpe_monitors = {}
+        monitors = {"monitors": {"remote": {"nrpe": nrpe_monitors}}}
+        for nrpecheck in self.checks:
+            nrpecheck.write(self.nagios_context, self.hostname,
+                            self.nagios_servicegroups)
+            nrpe_monitors[nrpecheck.shortname] = {
+                "command": nrpecheck.command,
+            }
+
+        service('restart', 'nagios-nrpe-server')
+
+        monitor_ids = relation_ids("local-monitors") + \
+            relation_ids("nrpe-external-master")
+        for rid in monitor_ids:
+            relation_set(relation_id=rid, monitors=yaml.dump(monitors))
+
+
+def get_nagios_hostcontext(relation_name='nrpe-external-master'):
+    """
+    Query relation with nrpe subordinate, return the nagios_host_context
+
+    :param str relation_name: Name of relation nrpe sub joined to
+    """
+    for rel in relations_of_type(relation_name):
+        if 'nagios_host_context' in rel:
+            return rel['nagios_host_context']
+
+
+def get_nagios_hostname(relation_name='nrpe-external-master'):
+    """
+    Query relation with nrpe subordinate, return the nagios_hostname
+
+    :param str relation_name: Name of relation nrpe sub joined to
+    """
+    for rel in relations_of_type(relation_name):
+        if 'nagios_hostname' in rel:
+            return rel['nagios_hostname']
+
+
+def get_nagios_unit_name(relation_name='nrpe-external-master'):
+    """
+    Return the nagios unit name prepended with host_context if needed
+
+    :param str relation_name: Name of relation nrpe sub joined to
+    """
+    host_context = get_nagios_hostcontext(relation_name)
+    if host_context:
+        unit = "%s:%s" % (host_context, local_unit())
+    else:
+        unit = local_unit()
+    return unit
+
+
+def add_init_service_checks(nrpe, services, unit_name):
+    """
+    Add checks for each service in list
+
+    :param NRPE nrpe: NRPE object to add check to
+    :param list services: List of services to check
+    :param str unit_name: Unit name to use in check description
+    """
+    for svc in services:
+        upstart_init = '/etc/init/%s.conf' % svc
+        sysv_init = '/etc/init.d/%s' % svc
+        if os.path.exists(upstart_init):
+            # Don't add a check for these services from neutron-gateway
+            if svc not in ['ext-port', 'os-charm-phy-nic-mtu']:
+                nrpe.add_check(
+                    shortname=svc,
+                    description='process check {%s}' % unit_name,
+                    check_cmd='check_upstart_job %s' % svc
+                )
+        elif os.path.exists(sysv_init):
+            cronpath = '/etc/cron.d/nagios-service-check-%s' % svc
+            cron_file = ('*/5 * * * * root '
+                         '/usr/local/lib/nagios/plugins/check_exit_status.pl '
+                         '-s /etc/init.d/%s status > '
+                         '/var/lib/nagios/service-check-%s.txt\n' % (svc,
+                                                                     svc)
+                         )
+            f = open(cronpath, 'w')
+            f.write(cron_file)
+            f.close()
+            nrpe.add_check(
+                shortname=svc,
+                description='process check {%s}' % unit_name,
+                check_cmd='check_status_file.py -f '
+                          '/var/lib/nagios/service-check-%s.txt' % svc,
+            )
+
+
+def copy_nrpe_checks():
+    """
+    Copy the nrpe checks into place
+
+    """
+    NAGIOS_PLUGINS = '/usr/local/lib/nagios/plugins'
+    nrpe_files_dir = os.path.join(os.getenv('CHARM_DIR'), 'hooks',
+                                  'charmhelpers', 'contrib', 'openstack',
+                                  'files')
+
+    if not os.path.exists(NAGIOS_PLUGINS):
+        os.makedirs(NAGIOS_PLUGINS)
+    for fname in glob.glob(os.path.join(nrpe_files_dir, "check_*")):
+        if os.path.isfile(fname):
+            shutil.copy2(fname,
+                         os.path.join(NAGIOS_PLUGINS, os.path.basename(fname)))
+
+
+def add_haproxy_checks(nrpe, unit_name):
+    """
+    Add checks for each service in list
+
+    :param NRPE nrpe: NRPE object to add check to
+    :param str unit_name: Unit name to use in check description
+    """
+    nrpe.add_check(
+        shortname='haproxy_servers',
+        description='Check HAProxy {%s}' % unit_name,
+        check_cmd='check_haproxy.sh')
+    nrpe.add_check(
+        shortname='haproxy_queue',
+        description='Check HAProxy queue depth {%s}' % unit_name,
+        check_cmd='check_haproxy_queue_depth.sh')

=== added file 'hooks/charmhelpers/contrib/charmsupport/volumes.py'
--- hooks/charmhelpers/contrib/charmsupport/volumes.py	1970-01-01 00:00:00 +0000
+++ hooks/charmhelpers/contrib/charmsupport/volumes.py	2016-05-19 16:36:23 +0000
@@ -0,0 +1,175 @@
+# 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/>.
+
+'''
+Functions for managing volumes in juju units. One volume is supported per unit.
+Subordinates may have their own storage, provided it is on its own partition.
+
+Configuration stanzas::
+
+  volume-ephemeral:
+    type: boolean
+    default: true
+    description: >
+      If false, a volume is mounted as sepecified in "volume-map"
+      If true, ephemeral storage will be used, meaning that log data
+         will only exist as long as the machine. YOU HAVE BEEN WARNED.
+  volume-map:
+    type: string
+    default: {}
+    description: >
+      YAML map of units to device names, e.g:
+        "{ rsyslog/0: /dev/vdb, rsyslog/1: /dev/vdb }"
+      Service units will raise a configure-error if volume-ephemeral
+      is 'true' and no volume-map value is set. Use 'juju set' to set a
+      value and 'juju resolved' to complete configuration.
+
+Usage::
+
+    from charmsupport.volumes import configure_volume, VolumeConfigurationError
+    from charmsupport.hookenv import log, ERROR
+    def post_mount_hook():
+        stop_service('myservice')
+    def post_mount_hook():
+        start_service('myservice')
+
+    if __name__ == '__main__':
+        try:
+            configure_volume(before_change=pre_mount_hook,
+                             after_change=post_mount_hook)
+        except VolumeConfigurationError:
+            log('Storage could not be configured', ERROR)
+
+'''
+
+# XXX: Known limitations
+# - fstab is neither consulted nor updated
+
+import os
+from charmhelpers.core import hookenv
+from charmhelpers.core import host
+import yaml
+
+
+MOUNT_BASE = '/srv/juju/volumes'
+
+
+class VolumeConfigurationError(Exception):
+    '''Volume configuration data is missing or invalid'''
+    pass
+
+
+def get_config():
+    '''Gather and sanity-check volume configuration data'''
+    volume_config = {}
+    config = hookenv.config()
+
+    errors = False
+
+    if config.get('volume-ephemeral') in (True, 'True', 'true', 'Yes', 'yes'):
+        volume_config['ephemeral'] = True
+    else:
+        volume_config['ephemeral'] = False
+
+    try:
+        volume_map = yaml.safe_load(config.get('volume-map', '{}'))
+    except yaml.YAMLError as e:
+        hookenv.log("Error parsing YAML volume-map: {}".format(e),
+                    hookenv.ERROR)
+        errors = True
+    if volume_map is None:
+        # probably an empty string
+        volume_map = {}
+    elif not isinstance(volume_map, dict):
+        hookenv.log("Volume-map should be a dictionary, not {}".format(
+            type(volume_map)))
+        errors = True
+
+    volume_config['device'] = volume_map.get(os.environ['JUJU_UNIT_NAME'])
+    if volume_config['device'] and volume_config['ephemeral']:
+        # asked for ephemeral storage but also defined a volume ID
+        hookenv.log('A volume is defined for this unit, but ephemeral '
+                    'storage was requested', hookenv.ERROR)
+        errors = True
+    elif not volume_config['device'] and not volume_config['ephemeral']:
+        # asked for permanent storage but did not define volume ID
+        hookenv.log('Ephemeral storage was requested, but there is no volume '
+                    'defined for this unit.', hookenv.ERROR)
+        errors = True
+
+    unit_mount_name = hookenv.local_unit().replace('/', '-')
+    volume_config['mountpoint'] = os.path.join(MOUNT_BASE, unit_mount_name)
+
+    if errors:
+        return None
+    return volume_config
+
+
+def mount_volume(config):
+    if os.path.exists(config['mountpoint']):
+        if not os.path.isdir(config['mountpoint']):
+            hookenv.log('Not a directory: {}'.format(config['mountpoint']))
+            raise VolumeConfigurationError()
+    else:
+        host.mkdir(config['mountpoint'])
+    if os.path.ismount(config['mountpoint']):
+        unmount_volume(config)
+    if not host.mount(config['device'], config['mountpoint'], persist=True):
+        raise VolumeConfigurationError()
+
+
+def unmount_volume(config):
+    if os.path.ismount(config['mountpoint']):
+        if not host.umount(config['mountpoint'], persist=True):
+            raise VolumeConfigurationError()
+
+
+def managed_mounts():
+    '''List of all mounted managed volumes'''
+    return filter(lambda mount: mount[0].startswith(MOUNT_BASE), host.mounts())
+
+
+def configure_volume(before_change=lambda: None, after_change=lambda: None):
+    '''Set up storage (or don't) according to the charm's volume configuration.
+       Returns the mount point or "ephemeral". before_change and after_change
+       are optional functions to be called if the volume configuration changes.
+    '''
+
+    config = get_config()
+    if not config:
+        hookenv.log('Failed to read volume configuration', hookenv.CRITICAL)
+        raise VolumeConfigurationError()
+
+    if config['ephemeral']:
+        if os.path.ismount(config['mountpoint']):
+            before_change()
+            unmount_volume(config)
+            after_change()
+        return 'ephemeral'
+    else:
+        # persistent storage
+        if os.path.ismount(config['mountpoint']):
+            mounts = dict(managed_mounts())
+            if mounts.get(config['mountpoint']) != config['device']:
+                before_change()
+                unmount_volume(config)
+                mount_volume(config)
+                after_change()
+        else:
+            before_change()
+            mount_volume(config)
+            after_change()
+        return config['mountpoint']

=== modified file 'hooks/hooks.py'
--- hooks/hooks.py	2016-03-30 22:10:17 +0000
+++ hooks/hooks.py	2016-05-19 16:36:23 +0000
@@ -26,6 +26,7 @@
     remote_unit,
     relation_get,
 )
+from charmhelpers.contrib.charmsupport import nrpe
 
 from charmhelpers.fetch import (
     apt_install
@@ -53,7 +54,7 @@
 
 IMFILE_FILE = '/etc/rsyslog.d/75-rsyslog-imfile.conf'
 LOGS_TEMPLATE = 'keep_local.template'
-LOGS_SYSTEM_FILE = '/etc/rsyslog.d/81-local.conf'
+LOGS_SYSTEM_FILE = '/etc/rsyslog.d/50-default.conf'
 REPLICATION_FILE = '/etc/rsyslog.d/80-rsyslog-replication.conf'
 
 
@@ -80,6 +81,18 @@
             os.remove(LOGS_SYSTEM_FILE)
 
 
[e-mail]("nrpe-external-master-relation-changed")
[e-mail]("local-monitors-relation-changed")
+def update_nrpe_config():
+    nrpe_compat = nrpe.NRPE()
+    nrpe_compat.add_check(
+        shortname="rsyslog",
+        description="Check rsyslog is running",
+        check_cmd="check_procs -c 1: -C rsyslogd"
+    )
+    nrpe_compat.write()
+
+
 def update_failover_replication(servers):
     """
     Set the configuration file to failover
@@ -142,7 +155,15 @@
 
 @hooks.hook()
 def stop():
-    service_stop("rsyslog")
+    # Remove any specific logfiles
+    for conf_file in (IMFILE_FILE, REPLICATION_FILE):
+        if os.path.exists(conf_file):
+            os.remove(conf_file)
+
+    # Unfortunately rsyslog reconfigure does not restore the default config
+    # so just put ours in place
+    update_local_logs(True)
+    service_restart("rsyslog")
 
 
 @hooks.hook()
@@ -199,6 +220,7 @@
     update_local_logs(config_get("log-locally"))
     update_imfile(config_get("watch-files").split())
     update_replication()
+    update_nrpe_config()
 
 
 if __name__ == "__main__":

=== added symlink 'hooks/nrpe-external-master-relation-changed'
=== target is u'hooks.py'
=== modified file 'metadata.yaml'
--- metadata.yaml	2015-10-02 17:29:40 +0000
+++ metadata.yaml	2016-05-19 16:36:23 +0000
@@ -5,6 +5,10 @@
 tags: ["system"]
 description: |
   Uses rsyslogs facilities to forward to multiple remote syslog servers.
+provides:
+  nrpe-external-master:
+    interface: nrpe-external-master
+    scope: container
 requires:
   juju-info:
     interface: juju-info

=== modified file 'templates/failover.template'
--- templates/failover.template	2016-03-23 20:20:05 +0000
+++ templates/failover.template	2016-05-19 16:36:23 +0000
@@ -1,5 +1,14 @@
 #this requires TCP is the protocol to be enabled on rsyslog
 
+# Explicitly set the tcp protocol to avoid collisions with
+# other config such as that used by Juju controllers
+$ActionSendStreamDriver ptcp
+$ActionSendStreamDriverMode 0
+
+$ActionQueueType LinkedList
+# Drop low priority messages when queue is near to backing up
+$ActionQueueDiscardMark 9500
+$ActionQueueDiscardSeverity info
 *.*   @@{{master.private_address}}:514
 
 $ActionExecOnlyWhenPreviousIsSuspended on

=== modified file 'tests/unit/test_basic.py'
--- tests/unit/test_basic.py	2016-03-30 21:54:14 +0000
+++ tests/unit/test_basic.py	2016-05-19 16:36:23 +0000
@@ -27,7 +27,7 @@
     "service_restart",
     "remote_unit",
     "service_start",
-    "service_stop",
+    "service_restart",
     "juju_log",
     "Server",
     "update_local_logs",
@@ -88,10 +88,10 @@
         self.service_start.assert_called_with("rsyslog")
 
     def test_stop_charm(self):
-        """Check if start hooks is correctly executed
+        """Check if rsyslog is returned to default config and restart executed
         """
         hooks.hooks.execute(['stop'])
-        self.service_stop.assert_called_with("rsyslog")
+        self.service_restart.assert_called_with("rsyslog")
 
     @mock.patch("hooks.hooks.update_replication")
     def test_syslog_relation_joined(self, replication):