Merge ~mpontillo/maas:rack-version-utils into maas:master

[Mike Pontillo]

Make version check utilities work for the rack.

This allows rack-only installations to determine their version.

Also moves code to determine MAAS version to the src/provisioningserver.

[Newell Jensen (newell-jensen)]

Looks good. Just one small suggestion.

review: Approve

[Mike Pontillo (mpontillo)]

Self-approving previously approved branch. (I resubmitted to land two related branches together.)

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b rack-version-utils lp:~mpontillo/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://ci-maas-jenkins.internal:8080/job/maas/job/branch-tester/92/console

f660088... by Mike Pontillo on 2017-07-12

Fix imports.

diff --git a/src/maasserver/__init__.py b/src/maasserver/__init__.py
index cd6b4d6..7d85981 100644
--- a/src/maasserver/__init__.py
+++ b/src/maasserver/__init__.py
@@ -13,8 +13,10 @@ __all__ = [
 import logging
 from os import environ
 
+from provisioningserver.utils import version
 
-__version__ = '2.3.0'
+
+__version__ = version.DEFAULT_VERSION
 
 default_app_config = 'maasserver.apps.MAASConfig'
 
diff --git a/src/maasserver/api/tests/test_version.py b/src/maasserver/api/tests/test_version.py
index b9204d2..defa1fb 100644
--- a/src/maasserver/api/tests/test_version.py
+++ b/src/maasserver/api/tests/test_version.py
@@ -13,7 +13,7 @@ from django.conf import settings
 from django.core.urlresolvers import reverse
 from maasserver.api.version import API_CAPABILITIES_LIST
 from maasserver.testing.api import APITestCase
-from maasserver.utils import version as version_module
+from provisioningserver.utils import version as version_module
 
 
 class TestVersionAPIBasics(APITestCase.ForAnonymousAndUserAndAdmin):
diff --git a/src/maasserver/api/version.py b/src/maasserver/api/version.py
index 3fc557b..77bb317 100644
--- a/src/maasserver/api/version.py
+++ b/src/maasserver/api/version.py
@@ -12,7 +12,7 @@ import json
 
 from django.http import HttpResponse
 from maasserver.api.support import AnonymousOperationsHandler
-from maasserver.utils.version import get_maas_version_subversion
+from provisioningserver.utils.version import get_maas_version_subversion
 
 # MAAS capabilities. See docs/version.rst for documentation.
 CAP_NETWORKS_MANAGEMENT = 'networks-management'
diff --git a/src/maasserver/bootresources.py b/src/maasserver/bootresources.py
index 996a6a0..fd7ede4 100644
--- a/src/maasserver/bootresources.py
+++ b/src/maasserver/bootresources.py
@@ -77,10 +77,6 @@ from maasserver.utils.orm import (
     with_connection,
 )
 from maasserver.utils.threads import deferToDatabase
-from maasserver.utils.version import (
-    get_maas_version_tuple,
-    get_maas_version_user_agent,
-)
 from provisioningserver.config import is_dev_environment
 from provisioningserver.events import EVENT_TYPES
 from provisioningserver.import_images.download_descriptions import (
@@ -111,6 +107,10 @@ from provisioningserver.utils.twisted import (
     pause,
     synchronous,
 )
+from provisioningserver.utils.version import (
+    get_maas_version_tuple,
+    get_maas_version_user_agent,
+)
 from simplestreams import util as sutil
 from simplestreams.mirrors import (
     BasicMirrorWriter,
diff --git a/src/maasserver/bootsources.py b/src/maasserver/bootsources.py
index 999a6d8..2cd5ab2 100644
--- a/src/maasserver/bootsources.py
+++ b/src/maasserver/bootsources.py
@@ -27,7 +27,6 @@ from maasserver.models import (
 )
 from maasserver.utils.orm import transactional
 from maasserver.utils.threads import deferToDatabase
-from maasserver.utils.version import get_maas_version_user_agent
 from provisioningserver.auth import get_maas_user_gpghome
 from provisioningserver.config import (
     DEFAULT_IMAGES_URL,
@@ -44,6 +43,7 @@ from provisioningserver.utils.twisted import (
     asynchronous,
     FOREVER,
 )
+from provisioningserver.utils.version import get_maas_version_user_agent
 from requests.exceptions import ConnectionError
 from twisted.internet.defer import inlineCallbacks
 
diff --git a/src/maasserver/context_processors.py b/src/maasserver/context_processors.py
index da8e817..697ec15 100644
--- a/src/maasserver/context_processors.py
+++ b/src/maasserver/context_processors.py
@@ -11,7 +11,7 @@ __all__ = [
 from django.conf import settings
 from maasserver.config import RegionConfiguration
 from maasserver.models import Config
-from maasserver.utils.version import (
+from provisioningserver.utils.version import (
     get_maas_doc_version,
     get_maas_version_ui,
 )
diff --git a/src/maasserver/tests/test_bootresources.py b/src/maasserver/tests/test_bootresources.py
index 135715b..b3fd049 100644
--- a/src/maasserver/tests/test_bootresources.py
+++ b/src/maasserver/tests/test_bootresources.py
@@ -92,7 +92,6 @@ from maasserver.utils.orm import (
     transactional,
 )
 from maasserver.utils.threads import deferToDatabase
-from maasserver.utils.version import get_maas_version_user_agent
 from maastesting.matchers import (
     MockCalledOnce,
     MockCalledOnceWith,
@@ -115,6 +114,7 @@ from provisioningserver.utils.twisted import (
     asynchronous,
     DeferredValue,
 )
+from provisioningserver.utils.version import get_maas_version_user_agent
 from testtools.matchers import (
     Contains,
     ContainsAll,
diff --git a/src/maasserver/tests/test_bootsources.py b/src/maasserver/tests/test_bootsources.py
index ecba7ce..d7f8ce8 100644
--- a/src/maasserver/tests/test_bootsources.py
+++ b/src/maasserver/tests/test_bootsources.py
@@ -42,7 +42,6 @@ from maasserver.testing.testcase import (
     MAASTransactionServerTestCase,
 )
 from maasserver.tests.test_bootresources import SimplestreamsEnvFixture
-from maasserver.utils.version import get_maas_version_user_agent
 from maastesting.matchers import MockCalledOnceWith
 from provisioningserver.config import DEFAULT_IMAGES_URL
 from provisioningserver.import_images import (
@@ -52,6 +51,7 @@ from provisioningserver.import_images.boot_image_mapping import (
     BootImageMapping,
 )
 from provisioningserver.import_images.helpers import ImageSpec
+from provisioningserver.utils.version import get_maas_version_user_agent
 from requests.exceptions import ConnectionError
 from testtools.matchers import HasLength
 
diff --git a/src/maasserver/utils/tests/test_version.py b/src/maasserver/utils/tests/test_version.py
deleted file mode 100644
index 92b31dd..0000000
--- a/src/maasserver/utils/tests/test_version.py
+++ /dev/null
@@ -1,278 +0,0 @@
-# Copyright 2015-2016 Canonical Ltd.  This software is licensed under the
-# GNU Affero General Public License version 3 (see the file LICENSE).
-
-"""Test version utilities."""
-
-__all__ = []
-
-import os.path
-import random
-from unittest import skipUnless
-from unittest.mock import (
-    MagicMock,
-    sentinel,
-)
-
-from maasserver import __version__ as old_version
-from maasserver.utils import version
-from maastesting import root
-from maastesting.matchers import MockCalledOnceWith
-from maastesting.testcase import MAASTestCase
-from provisioningserver.utils import (
-    shell,
-    snappy,
-)
-from testtools.matchers import (
-    GreaterThan,
-    Is,
-    IsInstance,
-)
-
-
-class TestGetVersionFromAPT(MAASTestCase):
-
-    def test__creates_cache_with_None_progress(self):
-        mock_Cache = self.patch(version.apt_pkg, "Cache")
-        version.get_version_from_apt(version.REGION_PACKAGE_NAME)
-        self.assertThat(mock_Cache, MockCalledOnceWith(None))
-
-    def test__returns_empty_string_if_package_not_in_cache(self):
-        self.patch(version.apt_pkg, "Cache")
-        self.assertEqual(
-            "",
-            version.get_version_from_apt(version.REGION_PACKAGE_NAME))
-
-    def test__returns_empty_string_if_not_current_ver_from_package(self):
-        package = MagicMock()
-        package.current_ver = None
-        mock_cache = {
-            version.REGION_PACKAGE_NAME: package,
-            }
-        self.patch(version.apt_pkg, "Cache").return_value = mock_cache
-        self.assertEqual(
-            "",
-            version.get_version_from_apt(version.REGION_PACKAGE_NAME))
-
-    def test__returns_ver_str_from_package(self):
-        package = MagicMock()
-        package.current_ver.ver_str = sentinel.ver_str
-        mock_cache = {
-            version.REGION_PACKAGE_NAME: package,
-            }
-        self.patch(version.apt_pkg, "Cache").return_value = mock_cache
-        self.assertIs(
-            sentinel.ver_str,
-            version.get_version_from_apt(version.REGION_PACKAGE_NAME))
-
-
-class TestGetMAASBranchVersion(MAASTestCase):
-
-    def test__returns_None_if_this_is_not_a_branch(self):
-        self.patch(version, "__file__", "/")
-        self.assertIsNone(version.get_maas_branch_version())
-
-    def test__returns_None_if_bzr_crashes(self):
-        call_and_check = self.patch(shell, "call_and_check")
-        call_and_check.side_effect = shell.ExternalProcessError(2, "cmd")
-        self.assertIsNone(version.get_maas_branch_version())
-
-    def test__returns_None_if_bzr_not_found(self):
-        call_and_check = self.patch(shell, "call_and_check")
-        call_and_check.side_effect = FileNotFoundError()
-        self.assertIsNone(version.get_maas_branch_version())
-
-    def test__returns_None_if_bzr_emits_something_thats_not_a_number(self):
-        call_and_check = self.patch(shell, "call_and_check")
-        call_and_check.return_value = b"???"
-        self.assertIsNone(version.get_maas_branch_version())
-
-    @skipUnless(os.path.isdir(os.path.join(root, ".bzr")), "Not a branch")
-    def test__returns_revno_for_this_branch(self):
-        revno = version.get_maas_branch_version()
-        self.assertThat(revno, IsInstance(int))
-        self.assertThat(revno, GreaterThan(0))
-
-
-class TestExtractVersionSubversion(MAASTestCase):
-
-    scenarios = [
-        ("with ~", {
-            "version": "2.2.0~beta4+bzr5856-0ubuntu1",
-            "output": ("2.2.0~beta4", "bzr5856-0ubuntu1"),
-            }),
-        ("without ~", {
-            "version": "2.1.0+bzr5480-0ubuntu1",
-            "output": ("2.1.0", "bzr5480-0ubuntu1"),
-            }),
-        ("without ~ or +", {
-            "version": "2.1.0-0ubuntu1",
-            "output": ("2.1.0", "0ubuntu1"),
-            }),
-    ]
-
-    def test__returns_version_subversion(self):
-        self.assertEqual(
-            self.output, version.extract_version_subversion(self.version))
-
-
-class TestVersionTestCase(MAASTestCase):
-    """MAASTestCase that resets the cache used by utility methods."""
-
-    def setUp(self):
-        super(TestVersionTestCase, self).setUp()
-        for attribute in vars(version).values():
-            if hasattr(attribute, "cache_clear"):
-                attribute.cache_clear()
-
-
-class TestGetMAASVersion(TestVersionTestCase):
-
-    def test__calls_get_version_from_apt(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = sentinel.version
-        self.expectThat(
-            version.get_maas_version(), Is(sentinel.version))
-        self.expectThat(
-            mock_apt, MockCalledOnceWith(version.REGION_PACKAGE_NAME))
-
-    def test__uses_snappy_get_snap_version(self):
-        self.patch(snappy, 'running_in_snap').return_value = True
-        self.patch(snappy, 'get_snap_version').return_value = sentinel.version
-        self.assertEqual(sentinel.version, version.get_maas_version())
-
-
-class TestGetMAASVersionSubversion(TestVersionTestCase):
-
-    def test__returns_package_version(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
-        self.assertEqual(
-            ("1.8.0~alpha4", "bzr356-0ubuntu1"),
-            version.get_maas_version_subversion())
-
-    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = None
-        self.assertEqual(
-            (old_version, "unknown"),
-            version.get_maas_version_subversion())
-
-    def test__returns_from_source_and_revno_from_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        revno = random.randint(1, 5000)
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = revno
-        self.assertEqual(
-            ("%s from source" % old_version, "bzr%d" % revno),
-            version.get_maas_version_subversion())
-
-
-class TestGetMAASVersionUI(TestVersionTestCase):
-
-    def test__returns_package_version(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
-        self.assertEqual(
-            "1.8.0~alpha4 (bzr356-0ubuntu1)", version.get_maas_version_ui())
-
-    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = None
-        self.assertEqual(
-            "%s (unknown)" % old_version,
-            version.get_maas_version_ui())
-
-    def test__returns_from_source_and_revno_from_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        revno = random.randint(1, 5000)
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = revno
-        self.assertEqual(
-            "%s from source (bzr%d)" % (old_version, revno),
-            version.get_maas_version_ui())
-
-
-class TestGetMAASVersionUserAgent(TestVersionTestCase):
-
-    def test__returns_package_version(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
-        self.assertEqual(
-            "maas/1.8.0~alpha4/bzr356-0ubuntu1",
-            version.get_maas_version_user_agent())
-
-    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = None
-        self.assertEqual(
-            "maas/%s/unknown" % old_version,
-            version.get_maas_version_user_agent())
-
-    def test__returns_from_source_and_revno_from_branch(self):
-        mock_version = self.patch(version, "get_version_from_apt")
-        mock_version.return_value = ""
-        revno = random.randint(1, 5000)
-        mock_branch_version = self.patch(version, "get_maas_branch_version")
-        mock_branch_version.return_value = revno
-        self.assertEqual(
-            "maas/%s from source/bzr%d" % (old_version, revno),
-            version.get_maas_version_user_agent())
-
-
-class TestGetMAASDocVersion(TestVersionTestCase):
-
-    def test__returns_doc_version_with_greater_than_1_decimals(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
-        self.assertEqual("1.8", version.get_maas_doc_version())
-
-    def test__returns_doc_version_with_equal_to_1_decimals(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8~alpha4+bzr356-0ubuntu1"
-        self.assertEqual("1.8", version.get_maas_doc_version())
-
-    def test__returns_empty_if_version_is_empty(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = ""
-        self.assertEqual("", version.get_maas_doc_version())
-
-
-class TestVersionMethodsCached(TestVersionTestCase):
-
-    scenarios = [
-        ("get_maas_version", dict(method="get_maas_version")),
-        ("get_maas_version_subversion", dict(
-            method="get_maas_version_subversion")),
-        ("get_maas_version_ui", dict(method="get_maas_version_ui")),
-        ("get_maas_doc_version", dict(method="get_maas_doc_version")),
-        ]
-
-    def test_method_is_cached(self):
-        mock_apt = self.patch(version, "get_version_from_apt")
-        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
-        cached_method = getattr(version, self.method)
-        first_return_value = cached_method()
-        second_return_value = cached_method()
-        # The return value is not empty (full unit tests have been performed
-        # earlier).
-        self.assertNotIn(first_return_value, [b'', '', None])
-        self.assertEqual(first_return_value, second_return_value)
-        # Apt has only been called once.
-        self.expectThat(
-            mock_apt, MockCalledOnceWith(version.REGION_PACKAGE_NAME))
-
-
-class TestGetMAASVersionTuple(MAASTestCase):
-
-    def test_get_maas_version_tuple(self):
-        self.assertEquals(
-            '.'.join([str(i) for i in version.get_maas_version_tuple()]),
-            version.get_maas_version_subversion()[0])
diff --git a/src/maasserver/utils/version.py b/src/maasserver/utils/version.py
deleted file mode 100644
index bdd6424..0000000
--- a/src/maasserver/utils/version.py
+++ /dev/null
@@ -1,142 +0,0 @@
-# Copyright 2015-2016 Canonical Ltd.  This software is licensed under the
-# GNU Affero General Public License version 3 (see the file LICENSE).
-
-"""Version utilities."""
-
-__all__ = [
-    "get_maas_doc_version",
-    "get_maas_version_subversion",
-    "get_maas_version_ui",
-    ]
-
-from functools import lru_cache
-import re
-
-from maasserver import __version__ as old_version
-from maasserver.api.logger import maaslog
-from provisioningserver.utils import (
-    shell,
-    snappy,
-)
-
-# Only import apt_pkg and initialize when not running in a snap.
-if not snappy.running_in_snap():
-    import apt_pkg
-    apt_pkg.init()
-
-# Name of maas package to get version from.
-REGION_PACKAGE_NAME = "maas-region-api"
-
-
-def get_version_from_apt(package):
-    """Return the version output from `apt_pkg.Cache` for the given package or
-    an error message if the package data is not valid."""
-    try:
-        cache = apt_pkg.Cache(None)
-    except SystemError:
-        maaslog.error(
-            'Installed version could not be determined. Ensure '
-            '/var/lib/dpkg/status is valid.')
-        return ""
-
-    version = None
-    if package in cache:
-        apt_package = cache[package]
-        version = apt_package.current_ver
-
-    return version.ver_str if version is not None else ""
-
-
-def extract_version_subversion(version):
-    """Return a tuple (version, subversion) from the given apt version."""
-    main_version, subversion = re.split('[+|-]', version, 1)
-    return main_version, subversion
-
-
-def get_maas_branch_version():
-    """Return the Bazaar revision for this running MAAS.
-
-    :return: An integer if MAAS is running from a Bazaar working tree, else
-        `None`. The revision number is only representative of the BRANCH, not
-        the working tree.
-    """
-    try:
-        revno = shell.call_and_check(("bzr", "revno", __file__))
-    except shell.ExternalProcessError:
-        # We may not be in a Bazaar working tree, or any manner of other
-        # errors. For the purposes of this function we don't care; simply say
-        # we don't know.
-        return None
-    except FileNotFoundError:
-        # Bazaar is not installed. We don't care and simply say we don't know.
-        return None
-    else:
-        # `bzr revno` can return '???' when it can't find the working tree's
-        # current revision in the branch. Hopefully a fairly unlikely thing to
-        # happen, but we guard against it, and other ills, here.
-        try:
-            return int(revno)
-        except ValueError:
-            return None
-
-
-@lru_cache(maxsize=1)
-def get_maas_version():
-    """Return the apt or snap version for the main MAAS package."""
-    if snappy.running_in_snap():
-        return snappy.get_snap_version()
-    else:
-        return get_version_from_apt(REGION_PACKAGE_NAME)
-
-
-@lru_cache(maxsize=1)
-def get_maas_version_subversion():
-    """Return a tuple with the MAAS version and the MAAS subversion."""
-    version = get_maas_version()
-    if version:
-        return extract_version_subversion(version)
-    else:
-        # Get the branch information
-        branch_version = get_maas_branch_version()
-        if branch_version is None:
-            # Not installed not in branch, then no way to identify. This should
-            # not happen, but just in case.
-            return old_version, "unknown"
-        else:
-            return "%s from source" % old_version, "bzr%d" % branch_version
-
-
-@lru_cache(maxsize=1)
-def get_maas_version_ui():
-    """Return the version string for the running MAAS region.
-
-    The returned string is suitable to display in the UI.
-    """
-    version, subversion = get_maas_version_subversion()
-    return "%s (%s)" % (version, subversion) if subversion else version
-
-
-@lru_cache(maxsize=1)
-def get_maas_version_user_agent():
-    """Return the version string for the running MAAS region.
-
-    The returned string is suitable to set the user agent.
-    """
-    version, subversion = get_maas_version_subversion()
-    return "maas/%s/%s" % (version, subversion)
-
-
-@lru_cache(maxsize=1)
-def get_maas_doc_version():
-    """Return the doc version for the running MAAS region."""
-    apt_version = get_maas_version()
-    if apt_version:
-        version, _ = extract_version_subversion(apt_version)
-        return '.'.join(version.split('~')[0].split('.')[:2])
-    else:
-        return ''
-
-
-def get_maas_version_tuple():
-    """Returns a tuple of the MAAS version without the svn rev."""
-    return tuple(int(x) for x in old_version.split('.'))
diff --git a/src/maasserver/websockets/handlers/bootresource.py b/src/maasserver/websockets/handlers/bootresource.py
index 1df2ecd..68742d9 100644
--- a/src/maasserver/websockets/handlers/bootresource.py
+++ b/src/maasserver/websockets/handlers/bootresource.py
@@ -43,7 +43,6 @@ from maasserver.models import (
 from maasserver.utils.converters import human_readable_bytes
 from maasserver.utils.orm import transactional
 from maasserver.utils.threads import deferToDatabase
-from maasserver.utils.version import get_maas_version_user_agent
 from maasserver.websockets.base import (
     Handler,
     HandlerError,
@@ -65,6 +64,7 @@ from provisioningserver.utils.twisted import (
     callOut,
     FOREVER,
 )
+from provisioningserver.utils.version import get_maas_version_user_agent
 from twisted.internet.defer import Deferred
 
 
diff --git a/src/maasserver/websockets/handlers/general.py b/src/maasserver/websockets/handlers/general.py
index b15300a..e5df4f0 100644
--- a/src/maasserver/websockets/handlers/general.py
+++ b/src/maasserver/websockets/handlers/general.py
@@ -33,9 +33,9 @@ from maasserver.utils.osystems import (
     list_osystem_choices,
     list_release_choices,
 )
-from maasserver.utils.version import get_maas_version_ui
 from maasserver.websockets.base import Handler
 import petname
+from provisioningserver.utils.version import get_maas_version_ui
 
 
 class GeneralHandler(Handler):
diff --git a/src/maasserver/websockets/handlers/tests/test_bootresource.py b/src/maasserver/websockets/handlers/tests/test_bootresource.py
index 57940a7..87438ea 100644
--- a/src/maasserver/websockets/handlers/tests/test_bootresource.py
+++ b/src/maasserver/websockets/handlers/tests/test_bootresource.py
@@ -32,7 +32,6 @@ from maasserver.utils.orm import (
     get_one,
     reload_object,
 )
-from maasserver.utils.version import get_maas_version_user_agent
 from maasserver.websockets.base import (
     HandlerError,
     HandlerValidationError,
@@ -54,6 +53,7 @@ from provisioningserver.import_images.testing.factory import (
     make_image_spec,
     set_resource,
 )
+from provisioningserver.utils.version import get_maas_version_user_agent
 from testtools.matchers import (
     ContainsAll,
     HasLength,
diff --git a/src/metadataserver/builtin_scripts/__init__.py b/src/metadataserver/builtin_scripts/__init__.py
index 934a3a1..8cff96f 100644
--- a/src/metadataserver/builtin_scripts/__init__.py
+++ b/src/metadataserver/builtin_scripts/__init__.py
@@ -15,10 +15,10 @@ from attr.validators import (
     instance_of,
     optional,
 )
-from maasserver.utils.version import get_maas_version
 from metadataserver.enum import SCRIPT_TYPE
 from metadataserver.models import Script
 from provisioningserver.utils.fs import read_text_file
+from provisioningserver.utils.version import get_maas_version
 from zope.interface import (
     Attribute,
     implementer,
diff --git a/src/metadataserver/builtin_scripts/tests/test_builtin_scripts.py b/src/metadataserver/builtin_scripts/tests/test_builtin_scripts.py
index 004560b..703ba94 100644
--- a/src/metadataserver/builtin_scripts/tests/test_builtin_scripts.py
+++ b/src/metadataserver/builtin_scripts/tests/test_builtin_scripts.py
@@ -11,13 +11,13 @@ from maasserver.models import VersionedTextFile
 from maasserver.testing.factory import factory
 from maasserver.testing.testcase import MAASServerTestCase
 from maasserver.utils.orm import reload_object
-from maasserver.utils.version import get_maas_version
 from metadataserver.builtin_scripts import (
     BUILTIN_SCRIPTS,
     load_builtin_scripts,
 )
 from metadataserver.enum import SCRIPT_TYPE_CHOICES
 from metadataserver.models import Script
+from provisioningserver.utils.version import get_maas_version
 
 
 class TestBuiltinScripts(MAASServerTestCase):
diff --git a/src/provisioningserver/utils/tests/test_version.py b/src/provisioningserver/utils/tests/test_version.py
new file mode 100644
index 0000000..410369d
--- /dev/null
+++ b/src/provisioningserver/utils/tests/test_version.py
@@ -0,0 +1,293 @@
+# Copyright 2015-2017 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Test version utilities."""
+
+__all__ = []
+
+
+import os.path
+import random
+from unittest import skipUnless
+from unittest.mock import (
+    MagicMock,
+    sentinel,
+)
+
+from maastesting import root
+from maastesting.matchers import MockCalledOnceWith
+from maastesting.testcase import MAASTestCase
+from provisioningserver.utils import (
+    shell,
+    snappy,
+    version,
+)
+from provisioningserver.utils.version import DEFAULT_VERSION as old_version
+from testtools.matchers import (
+    GreaterThan,
+    Is,
+    IsInstance,
+)
+
+
+class TestGetVersionFromAPT(MAASTestCase):
+
+    def test__creates_cache_with_None_progress(self):
+        mock_Cache = self.patch(version.apt_pkg, "Cache")
+        version.get_version_from_apt(version.REGION_PACKAGE_NAME)
+        self.assertThat(mock_Cache, MockCalledOnceWith(None))
+
+    def test__returns_empty_string_if_package_not_in_cache(self):
+        self.patch(version.apt_pkg, "Cache")
+        self.assertEqual(
+            "",
+            version.get_version_from_apt(version.REGION_PACKAGE_NAME))
+
+    def test__returns_empty_string_if_not_current_ver_from_package(self):
+        package = MagicMock()
+        package.current_ver = None
+        mock_cache = {
+            version.REGION_PACKAGE_NAME: package,
+            }
+        self.patch(version.apt_pkg, "Cache").return_value = mock_cache
+        self.assertEqual(
+            "",
+            version.get_version_from_apt(version.REGION_PACKAGE_NAME))
+
+    def test__returns_ver_str_from_package(self):
+        package = MagicMock()
+        package.current_ver.ver_str = sentinel.ver_str
+        mock_cache = {
+            version.RACK_PACKAGE_NAME: package
+            }
+        self.patch(version.apt_pkg, "Cache").return_value = mock_cache
+        self.assertIs(
+            sentinel.ver_str,
+            version.get_version_from_apt(version.RACK_PACKAGE_NAME))
+
+    def test__returns_ver_str_from_second_package_if_first_not_found(self):
+        package = MagicMock()
+        package.current_ver.ver_str = sentinel.ver_str
+        mock_cache = {
+            version.REGION_PACKAGE_NAME: package,
+        }
+        self.patch(version.apt_pkg, "Cache").return_value = mock_cache
+        self.assertIs(
+            sentinel.ver_str,
+            version.get_version_from_apt(
+                version.RACK_PACKAGE_NAME, version.REGION_PACKAGE_NAME))
+
+
+class TestGetMAASBranchVersion(MAASTestCase):
+
+    def test__returns_None_if_this_is_not_a_branch(self):
+        self.patch(version, "__file__", "/")
+        self.assertIsNone(version.get_maas_branch_version())
+
+    def test__returns_None_if_bzr_crashes(self):
+        call_and_check = self.patch(shell, "call_and_check")
+        call_and_check.side_effect = shell.ExternalProcessError(2, "cmd")
+        self.assertIsNone(version.get_maas_branch_version())
+
+    def test__returns_None_if_bzr_not_found(self):
+        call_and_check = self.patch(shell, "call_and_check")
+        call_and_check.side_effect = FileNotFoundError()
+        self.assertIsNone(version.get_maas_branch_version())
+
+    def test__returns_None_if_bzr_emits_something_thats_not_a_number(self):
+        call_and_check = self.patch(shell, "call_and_check")
+        call_and_check.return_value = b"???"
+        self.assertIsNone(version.get_maas_branch_version())
+
+    @skipUnless(os.path.isdir(os.path.join(root, ".bzr")), "Not a branch")
+    def test__returns_revno_for_this_branch(self):
+        revno = version.get_maas_branch_version()
+        self.assertThat(revno, IsInstance(int))
+        self.assertThat(revno, GreaterThan(0))
+
+
+class TestExtractVersionSubversion(MAASTestCase):
+
+    scenarios = [
+        ("with ~", {
+            "version": "2.2.0~beta4+bzr5856-0ubuntu1",
+            "output": ("2.2.0~beta4", "bzr5856-0ubuntu1"),
+            }),
+        ("without ~", {
+            "version": "2.1.0+bzr5480-0ubuntu1",
+            "output": ("2.1.0", "bzr5480-0ubuntu1"),
+            }),
+        ("without ~ or +", {
+            "version": "2.1.0-0ubuntu1",
+            "output": ("2.1.0", "0ubuntu1"),
+            }),
+    ]
+
+    def test__returns_version_subversion(self):
+        self.assertEqual(
+            self.output, version.extract_version_subversion(self.version))
+
+
+class TestVersionTestCase(MAASTestCase):
+    """MAASTestCase that resets the cache used by utility methods."""
+
+    def setUp(self):
+        super(TestVersionTestCase, self).setUp()
+        for attribute in vars(version).values():
+            if hasattr(attribute, "cache_clear"):
+                attribute.cache_clear()
+
+
+class TestGetMAASVersion(TestVersionTestCase):
+
+    def test__calls_get_version_from_apt(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = sentinel.version
+        self.expectThat(
+            version.get_maas_version(), Is(sentinel.version))
+        self.expectThat(
+            mock_apt, MockCalledOnceWith(
+                version.RACK_PACKAGE_NAME, version.REGION_PACKAGE_NAME))
+
+    def test__uses_snappy_get_snap_version(self):
+        self.patch(snappy, 'running_in_snap').return_value = True
+        self.patch(snappy, 'get_snap_version').return_value = sentinel.version
+        self.assertEqual(sentinel.version, version.get_maas_version())
+
+
+class TestGetMAASVersionSubversion(TestVersionTestCase):
+
+    def test__returns_package_version(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
+        self.assertEqual(
+            ("1.8.0~alpha4", "bzr356-0ubuntu1"),
+            version.get_maas_version_subversion())
+
+    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = None
+        self.assertEqual(
+            (old_version, "unknown"),
+            version.get_maas_version_subversion())
+
+    def test__returns_from_source_and_revno_from_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        revno = random.randint(1, 5000)
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = revno
+        self.assertEqual(
+            ("%s from source" % old_version, "bzr%d" % revno),
+            version.get_maas_version_subversion())
+
+
+class TestGetMAASVersionUI(TestVersionTestCase):
+
+    def test__returns_package_version(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
+        self.assertEqual(
+            "1.8.0~alpha4 (bzr356-0ubuntu1)", version.get_maas_version_ui())
+
+    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = None
+        self.assertEqual(
+            "%s (unknown)" % old_version,
+            version.get_maas_version_ui())
+
+    def test__returns_from_source_and_revno_from_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        revno = random.randint(1, 5000)
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = revno
+        self.assertEqual(
+            "%s from source (bzr%d)" % (old_version, revno),
+            version.get_maas_version_ui())
+
+
+class TestGetMAASVersionUserAgent(TestVersionTestCase):
+
+    def test__returns_package_version(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
+        self.assertEqual(
+            "maas/1.8.0~alpha4/bzr356-0ubuntu1",
+            version.get_maas_version_user_agent())
+
+    def test__returns_unknown_if_version_is_empty_and_not_bzr_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = None
+        self.assertEqual(
+            "maas/%s/unknown" % old_version,
+            version.get_maas_version_user_agent())
+
+    def test__returns_from_source_and_revno_from_branch(self):
+        mock_version = self.patch(version, "get_version_from_apt")
+        mock_version.return_value = ""
+        revno = random.randint(1, 5000)
+        mock_branch_version = self.patch(version, "get_maas_branch_version")
+        mock_branch_version.return_value = revno
+        self.assertEqual(
+            "maas/%s from source/bzr%d" % (old_version, revno),
+            version.get_maas_version_user_agent())
+
+
+class TestGetMAASDocVersion(TestVersionTestCase):
+
+    def test__returns_doc_version_with_greater_than_1_decimals(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
+        self.assertEqual("1.8", version.get_maas_doc_version())
+
+    def test__returns_doc_version_with_equal_to_1_decimals(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8~alpha4+bzr356-0ubuntu1"
+        self.assertEqual("1.8", version.get_maas_doc_version())
+
+    def test__returns_empty_if_version_is_empty(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = ""
+        self.assertEqual("", version.get_maas_doc_version())
+
+
+class TestVersionMethodsCached(TestVersionTestCase):
+
+    scenarios = [
+        ("get_maas_version", dict(method="get_maas_version")),
+        ("get_maas_version_subversion", dict(
+            method="get_maas_version_subversion")),
+        ("get_maas_version_ui", dict(method="get_maas_version_ui")),
+        ("get_maas_doc_version", dict(method="get_maas_doc_version")),
+        ]
+
+    def test_method_is_cached(self):
+        mock_apt = self.patch(version, "get_version_from_apt")
+        mock_apt.return_value = "1.8.0~alpha4+bzr356-0ubuntu1"
+        cached_method = getattr(version, self.method)
+        first_return_value = cached_method()
+        second_return_value = cached_method()
+        # The return value is not empty (full unit tests have been performed
+        # earlier).
+        self.assertNotIn(first_return_value, [b'', '', None])
+        self.assertEqual(first_return_value, second_return_value)
+        # Apt has only been called once.
+        self.expectThat(
+            mock_apt, MockCalledOnceWith(
+                version.RACK_PACKAGE_NAME, version.REGION_PACKAGE_NAME))
+
+
+class TestGetMAASVersionTuple(MAASTestCase):
+
+    def test_get_maas_version_tuple(self):
+        self.assertEquals(
+            '.'.join([str(i) for i in version.get_maas_version_tuple()]),
+            version.get_maas_version_subversion()[0])
diff --git a/src/provisioningserver/utils/version.py b/src/provisioningserver/utils/version.py
new file mode 100644
index 0000000..f372b0d
--- /dev/null
+++ b/src/provisioningserver/utils/version.py
@@ -0,0 +1,149 @@
+# Copyright 2015-2017 Canonical Ltd.  This software is licensed under the
+# GNU Affero General Public License version 3 (see the file LICENSE).
+
+"""Version utilities."""
+
+__all__ = [
+    "get_maas_doc_version",
+    "get_maas_version_subversion",
+    "get_maas_version_ui",
+    ]
+
+from functools import lru_cache
+import re
+
+from provisioningserver.logger import get_maas_logger
+from provisioningserver.utils import (
+    shell,
+    snappy,
+)
+
+
+maaslog = get_maas_logger('version')
+
+DEFAULT_VERSION = "2.3.0"
+
+# Only import apt_pkg and initialize when not running in a snap.
+if not snappy.running_in_snap():
+    import apt_pkg
+    apt_pkg.init()
+
+# Name of maas package to get version from.
+REGION_PACKAGE_NAME = "maas-region-api"
+RACK_PACKAGE_NAME = "maas-rack-controller"
+
+
+def get_version_from_apt(*packages):
+    """Return the version output from `apt_pkg.Cache` for the given package(s),
+     or log an error message if the package data is not valid."""
+    try:
+        cache = apt_pkg.Cache(None)
+    except SystemError:
+        maaslog.error(
+            'Installed version could not be determined. Ensure '
+            '/var/lib/dpkg/status is valid.')
+        return ""
+
+    version = None
+    for package in packages:
+        if package in cache:
+            apt_package = cache[package]
+            version = apt_package.current_ver
+            break
+
+    return version.ver_str if version is not None else ""
+
+
+def extract_version_subversion(version):
+    """Return a tuple (version, subversion) from the given apt version."""
+    main_version, subversion = re.split('[+|-]', version, 1)
+    return main_version, subversion
+
+
+def get_maas_branch_version():
+    """Return the Bazaar revision for this running MAAS.
+
+    :return: An integer if MAAS is running from a Bazaar working tree, else
+        `None`. The revision number is only representative of the BRANCH, not
+        the working tree.
+    """
+    try:
+        revno = shell.call_and_check(("bzr", "revno", __file__))
+    except shell.ExternalProcessError:
+        # We may not be in a Bazaar working tree, or any manner of other
+        # errors. For the purposes of this function we don't care; simply say
+        # we don't know.
+        return None
+    except FileNotFoundError:
+        # Bazaar is not installed. We don't care and simply say we don't know.
+        return None
+    else:
+        # `bzr revno` can return '???' when it can't find the working tree's
+        # current revision in the branch. Hopefully a fairly unlikely thing to
+        # happen, but we guard against it, and other ills, here.
+        try:
+            return int(revno)
+        except ValueError:
+            return None
+
+
+@lru_cache(maxsize=1)
+def get_maas_version():
+    """Return the apt or snap version for the main MAAS package."""
+    if snappy.running_in_snap():
+        return snappy.get_snap_version()
+    else:
+        return get_version_from_apt(RACK_PACKAGE_NAME, REGION_PACKAGE_NAME)
+
+
+@lru_cache(maxsize=1)
+def get_maas_version_subversion():
+    """Return a tuple with the MAAS version and the MAAS subversion."""
+    version = get_maas_version()
+    if version:
+        return extract_version_subversion(version)
+    else:
+        # Get the branch information
+        branch_version = get_maas_branch_version()
+        if branch_version is None:
+            # Not installed not in branch, then no way to identify. This should
+            # not happen, but just in case.
+            return DEFAULT_VERSION, "unknown"
+        else:
+            return "%s from source" % DEFAULT_VERSION, "bzr%d" % branch_version
+
+
+@lru_cache(maxsize=1)
+def get_maas_version_ui():
+    """Return the version string for the running MAAS region.
+
+    The returned string is suitable to display in the UI.
+    """
+    version, subversion = get_maas_version_subversion()
+    return "%s (%s)" % (version, subversion) if subversion else version
+
+
+@lru_cache(maxsize=1)
+def get_maas_version_user_agent():
+    """Return the version string for the running MAAS region.
+
+    The returned string is suitable to set the user agent.
+    """
+    version, subversion = get_maas_version_subversion()
+    return "maas/%s/%s" % (version, subversion)
+
+
+@lru_cache(maxsize=1)
+def get_maas_doc_version():
+    """Return the doc version for the running MAAS region."""
+    apt_version = get_maas_version()
+    if apt_version:
+        version, _ = extract_version_subversion(apt_version)
+        return '.'.join(version.split('~')[0].split('.')[:2])
+    else:
+        return ''
+
+
+def get_maas_version_tuple():
+    """Returns a tuple of the MAAS version without the svn rev."""
+    return tuple(int(x) for x in DEFAULT_VERSION.split('.'))
diff --git a/utilities/check-imports b/utilities/check-imports
index 405ca8d..d047e70 100755
--- a/utilities/check-imports
+++ b/utilities/check-imports
@@ -195,6 +195,7 @@ RackControllerRule = Rule(
     Allow("apiclient.creds.*"),
     Allow("apiclient.maas_client.*"),
     Allow("apiclient.utils.*"),
+    Allow("apt_pkg"),
     Allow("attr|attr.**"),
     Allow("bson|bson.**"),
     Allow("crochet|crochet.**"),
@@ -245,7 +246,6 @@ RegionControllerRule = Rule(
     Allow("apiclient.creds.*"),
     Allow("apiclient.multipart.*"),
     Allow("apiclient.utils.*"),
-    Allow("apt_pkg"),
     Allow("attr|attr.**"),
     Allow("bson"),
     Allow("convoy|convoy.**"),