Enable Ocata Amulet Tests

- Add Zesty as a supported series to metadata.yaml.
- Turn on Xenial-Ocata Amulet test definitions.
- Sync charm helpers to get Juju 2.x amulet compatibility.
- Keeping Zesty-Ocata Amulet test definitions turned off until the
  metadata.yaml changes propagate to the charm store.

Change-Id: Idf45ef0e0587e6874e29145c7ce1109be7cc4e50

charm-helpers-tests.yaml

@@ -4,3 +4,4 @@ include:
     - core
     - contrib.amulet
     - contrib.openstack.amulet
+    - osplatform

hooks/charmhelpers/contrib/network/ip.py

@@ -31,6 +31,7 @@ from charmhelpers.core.hookenv import (
 
 from charmhelpers.core.host import (
     lsb_release,
+    CompareHostReleases,
 )
 
 try:
@@ -67,6 +68,24 @@ def no_ip_found_error_out(network):
     raise ValueError(errmsg)
 
 
+def _get_ipv6_network_from_address(address):
+    """Get an netaddr.IPNetwork for the given IPv6 address
+    :param address: a dict as returned by netifaces.ifaddresses
+    :returns netaddr.IPNetwork: None if the address is a link local or loopback
+    address
+    """
+    if address['addr'].startswith('fe80') or address['addr'] == "::1":
+        return None
+
+    prefix = address['netmask'].split("/")
+    if len(prefix) > 1:
+        netmask = prefix[1]
+    else:
+        netmask = address['netmask']
+    return netaddr.IPNetwork("%s/%s" % (address['addr'],
+                                        netmask))
+
+
 def get_address_in_network(network, fallback=None, fatal=False):
     """Get an IPv4 or IPv6 address within the network from the host.
 
@@ -100,11 +119,9 @@ def get_address_in_network(network, fallback=None, fatal=False):
 
             if network.version == 6 and netifaces.AF_INET6 in addresses:
                 for addr in addresses[netifaces.AF_INET6]:
-                    if not addr['addr'].startswith('fe80'):
-                        cidr = netaddr.IPNetwork("%s/%s" % (addr['addr'],
-                                                            addr['netmask']))
-                        if cidr in network:
-                            return str(cidr.ip)
+                    cidr = _get_ipv6_network_from_address(addr)
+                    if cidr and cidr in network:
+                        return str(cidr.ip)
 
     if fallback is not None:
         return fallback
@@ -180,18 +197,18 @@ def _get_for_address(address, key):
 
         if address.version == 6 and netifaces.AF_INET6 in addresses:
             for addr in addresses[netifaces.AF_INET6]:
-                if not addr['addr'].startswith('fe80'):
-                    network = netaddr.IPNetwork("%s/%s" % (addr['addr'],
-                                                           addr['netmask']))
-                    cidr = network.cidr
-                    if address in cidr:
-                        if key == 'iface':
-                            return iface
-                        elif key == 'netmask' and cidr:
-                            return str(cidr).split('/')[1]
-                        else:
-                            return addr[key]
+                network = _get_ipv6_network_from_address(addr)
+                if not network:
+                    continue
 
+                cidr = network.cidr
+                if address in cidr:
+                    if key == 'iface':
+                        return iface
+                    elif key == 'netmask' and cidr:
+                        return str(cidr).split('/')[1]
+                    else:
+                        return addr[key]
     return None
 
 
@@ -521,7 +538,8 @@ def port_has_listener(address, port):
 
 def assert_charm_supports_ipv6():
     """Check whether we are able to support charms ipv6."""
-    if lsb_release()['DISTRIB_CODENAME'].lower() < "trusty":
+    release = lsb_release()['DISTRIB_CODENAME'].lower()
+    if CompareHostReleases(release) < "trusty":
         raise Exception("IPv6 is not supported in the charms for Ubuntu "
                         "versions less than Trusty 14.04")
 

hooks/charmhelpers/contrib/openstack/amulet/utils.py

@@ -40,6 +40,7 @@ from charmhelpers.contrib.amulet.utils import (
     AmuletUtils
 )
 from charmhelpers.core.decorators import retry_on_exception
+from charmhelpers.core.host import CompareHostReleases
 
 DEBUG = logging.DEBUG
 ERROR = logging.ERROR
@@ -1255,7 +1256,7 @@ class OpenStackAmuletUtils(AmuletUtils):
         contents = self.file_contents_safe(sentry_unit, '/etc/memcached.conf',
                                            fatal=True)
         ubuntu_release, _ = self.run_cmd_unit(sentry_unit, 'lsb_release -cs')
-        if ubuntu_release <= 'trusty':
+        if CompareHostReleases(ubuntu_release) <= 'trusty':
             memcache_listen_addr = 'ip6-localhost'
         else:
             memcache_listen_addr = '::1'

hooks/charmhelpers/contrib/openstack/context.py

@@ -59,6 +59,7 @@ from charmhelpers.core.host import (
     write_file,
     pwgen,
     lsb_release,
+    CompareHostReleases,
 )
 from charmhelpers.contrib.hahelpers.cluster import (
     determine_apache_port,
@@ -155,7 +156,8 @@ class OSContextGenerator(object):
 
         if self.missing_data:
             self.complete = False
-            log('Missing required data: %s' % ' '.join(self.missing_data), level=INFO)
+            log('Missing required data: %s' % ' '.join(self.missing_data),
+                level=INFO)
         else:
             self.complete = True
         return self.complete
@@ -213,8 +215,9 @@ class SharedDBContext(OSContextGenerator):
                 hostname_key = "{}_hostname".format(self.relation_prefix)
             else:
                 hostname_key = "hostname"
-            access_hostname = get_address_in_network(access_network,
-                                                     unit_get('private-address'))
+            access_hostname = get_address_in_network(
+                access_network,
+                unit_get('private-address'))
             set_hostname = relation_get(attribute=hostname_key,
                                         unit=local_unit())
             if set_hostname != access_hostname:
@@ -308,7 +311,10 @@ def db_ssl(rdata, ctxt, ssl_dir):
 
 class IdentityServiceContext(OSContextGenerator):
 
-    def __init__(self, service=None, service_user=None, rel_name='identity-service'):
+    def __init__(self,
+                 service=None,
+                 service_user=None,
+                 rel_name='identity-service'):
         self.service = service
         self.service_user = service_user
         self.rel_name = rel_name
@@ -457,19 +463,17 @@ class AMQPContext(OSContextGenerator):
                     host = format_ipv6_addr(host) or host
                     rabbitmq_hosts.append(host)
 
-                ctxt['rabbitmq_hosts'] = ','.join(sorted(rabbitmq_hosts))
+                rabbitmq_hosts = sorted(rabbitmq_hosts)
+                ctxt['rabbitmq_hosts'] = ','.join(rabbitmq_hosts)
                 transport_hosts = rabbitmq_hosts
 
             if transport_hosts:
-                transport_url_hosts = ''
-                for host in transport_hosts:
-                    if transport_url_hosts:
-                        format_string = ",{}:{}@{}:{}"
-                    else:
-                        format_string = "{}:{}@{}:{}"
-                    transport_url_hosts += format_string.format(
-                        ctxt['rabbitmq_user'], ctxt['rabbitmq_password'],
-                        host, rabbitmq_port)
+                transport_url_hosts = ','.join([
+                    "{}:{}@{}:{}".format(ctxt['rabbitmq_user'],
+                                         ctxt['rabbitmq_password'],
+                                         host_,
+                                         rabbitmq_port)
+                    for host_ in transport_hosts])
                 ctxt['transport_url'] = "rabbit://{}/{}".format(
                     transport_url_hosts, vhost)
 
@@ -1601,7 +1605,8 @@ class MemcacheContext(OSContextGenerator):
         if ctxt['use_memcache']:
             # Trusty version of memcached does not support ::1 as a listen
             # address so use host file entry instead
-            if lsb_release()['DISTRIB_CODENAME'].lower() > 'trusty':
+            release = lsb_release()['DISTRIB_CODENAME'].lower()
+            if CompareHostReleases(release) > 'trusty':
                 ctxt['memcache_server'] = '::1'
             else:
                 ctxt['memcache_server'] = 'ip6-localhost'

hooks/charmhelpers/contrib/openstack/neutron.py

@@ -23,7 +23,10 @@ from charmhelpers.core.hookenv import (
     ERROR,
 )
 
-from charmhelpers.contrib.openstack.utils import os_release
+from charmhelpers.contrib.openstack.utils import (
+    os_release,
+    CompareOpenStackReleases,
+)
 
 
 def headers_package():
@@ -198,7 +201,8 @@ def neutron_plugins():
         },
         'plumgrid': {
             'config': '/etc/neutron/plugins/plumgrid/plumgrid.ini',
-            'driver': 'neutron.plugins.plumgrid.plumgrid_plugin.plumgrid_plugin.NeutronPluginPLUMgridV2',
+            'driver': ('neutron.plugins.plumgrid.plumgrid_plugin'
+                       '.plumgrid_plugin.NeutronPluginPLUMgridV2'),
             'contexts': [
                 context.SharedDBContext(user=config('database-user'),
                                         database=config('database'),
@@ -225,7 +229,7 @@ def neutron_plugins():
             'server_services': ['neutron-server']
         }
     }
-    if release >= 'icehouse':
+    if CompareOpenStackReleases(release) >= 'icehouse':
         # NOTE: patch in ml2 plugin for icehouse onwards
         plugins['ovs']['config'] = '/etc/neutron/plugins/ml2/ml2_conf.ini'
         plugins['ovs']['driver'] = 'neutron.plugins.ml2.plugin.Ml2Plugin'
@@ -233,10 +237,10 @@ def neutron_plugins():
                                              'neutron-plugin-ml2']
         # NOTE: patch in vmware renames nvp->nsx for icehouse onwards
         plugins['nvp'] = plugins['nsx']
-    if release >= 'kilo':
+    if CompareOpenStackReleases(release) >= 'kilo':
         plugins['midonet']['driver'] = (
             'neutron.plugins.midonet.plugin.MidonetPluginV2')
-    if release >= 'liberty':
+    if CompareOpenStackReleases(release) >= 'liberty':
         plugins['midonet']['driver'] = (
             'midonet.neutron.plugin_v1.MidonetPluginV2')
         plugins['midonet']['server_packages'].remove(
@@ -244,10 +248,11 @@ def neutron_plugins():
         plugins['midonet']['server_packages'].append(
             'python-networking-midonet')
         plugins['plumgrid']['driver'] = (
-            'networking_plumgrid.neutron.plugins.plugin.NeutronPluginPLUMgridV2')
+            'networking_plumgrid.neutron.plugins'
+            '.plugin.NeutronPluginPLUMgridV2')
         plugins['plumgrid']['server_packages'].remove(
             'neutron-plugin-plumgrid')
-    if release >= 'mitaka':
+    if CompareOpenStackReleases(release) >= 'mitaka':
         plugins['nsx']['server_packages'].remove('neutron-plugin-vmware')
         plugins['nsx']['server_packages'].append('python-vmware-nsx')
         plugins['nsx']['config'] = '/etc/neutron/nsx.ini'

hooks/charmhelpers/contrib/openstack/utils.py

@@ -33,9 +33,7 @@ import yaml
 
 from charmhelpers.contrib.network import ip
 
-from charmhelpers.core import (
-    unitdata,
-)
+from charmhelpers.core import unitdata
 
 from charmhelpers.core.hookenv import (
     action_fail,
@@ -55,6 +53,8 @@ from charmhelpers.core.hookenv import (
     application_version_set,
 )
 
+from charmhelpers.core.strutils import BasicStringComparator
+
 from charmhelpers.contrib.storage.linux.lvm import (
     deactivate_lvm_volume_group,
     is_lvm_physical_volume,
@@ -97,6 +97,22 @@ CLOUD_ARCHIVE_KEY_ID = '5EDB1B62EC4926EA'
 DISTRO_PROPOSED = ('deb http://archive.ubuntu.com/ubuntu/ %s-proposed '
                    'restricted main multiverse universe')
 
+OPENSTACK_RELEASES = (
+    'diablo',
+    'essex',
+    'folsom',
+    'grizzly',
+    'havana',
+    'icehouse',
+    'juno',
+    'kilo',
+    'liberty',
+    'mitaka',
+    'newton',
+    'ocata',
+    'pike',
+)
+
 UBUNTU_OPENSTACK_RELEASE = OrderedDict([
     ('oneiric', 'diablo'),
     ('precise', 'essex'),
@@ -238,6 +254,17 @@ GIT_DEFAULT_BRANCHES = {
 DEFAULT_LOOPBACK_SIZE = '5G'
 
 
+class CompareOpenStackReleases(BasicStringComparator):
+    """Provide comparisons of OpenStack releases.
+
+    Use in the form of
+
+    if CompareOpenStackReleases(release) > 'mitaka':
+        # do something with mitaka
+    """
+    _list = OPENSTACK_RELEASES
+
+
 def error_out(msg):
     juju_log("FATAL ERROR: %s" % msg, level='ERROR')
     sys.exit(1)
@@ -1066,7 +1093,8 @@ def git_generate_systemd_init_files(templates_dir):
 
             shutil.copyfile(init_in_source, init_source)
             with open(init_source, 'a') as outfile:
-                template = '/usr/share/openstack-pkg-tools/init-script-template'
+                template = ('/usr/share/openstack-pkg-tools/'
+                            'init-script-template')
                 with open(template) as infile:
                     outfile.write('\n\n{}'.format(infile.read()))
 
@@ -1971,9 +1999,7 @@ def enable_memcache(source=None, release=None, package=None):
     if not _release:
         _release = get_os_codename_install_source(source)
 
-    # TODO: this should be changed to a numeric comparison using a known list
-    # of releases and comparing by index.
-    return _release >= 'mitaka'
+    return CompareOpenStackReleases(_release) >= 'mitaka'
 
 
 def token_cache_pkgs(source=None, release=None):

hooks/charmhelpers/core/host.py

@@ -45,6 +45,7 @@ if __platform__ == "ubuntu":
         add_new_group,
         lsb_release,
         cmp_pkgrevno,
+        CompareHostReleases,
     )  # flake8: noqa -- ignore F401 for this import
 elif __platform__ == "centos":
     from charmhelpers.core.host_factory.centos import (
@@ -52,6 +53,7 @@ elif __platform__ == "centos":
         add_new_group,
         lsb_release,
         cmp_pkgrevno,
+        CompareHostReleases,
     )  # flake8: noqa -- ignore F401 for this import
 
 UPDATEDB_PATH = '/etc/updatedb.conf'

hooks/charmhelpers/core/host_factory/centos.py

@@ -2,6 +2,22 @@ import subprocess
 import yum
 import os
 
+from charmhelpers.core.strutils import BasicStringComparator
+
+
+class CompareHostReleases(BasicStringComparator):
+    """Provide comparisons of Host releases.
+
+    Use in the form of
+
+    if CompareHostReleases(release) > 'trusty':
+        # do something with mitaka
+    """
+
+    def __init__(self, item):
+        raise NotImplementedError(
+            "CompareHostReleases() is not implemented for CentOS")
+
 
 def service_available(service_name):
     # """Determine whether a system service is available."""

hooks/charmhelpers/core/host_factory/ubuntu.py

@@ -1,5 +1,37 @@
 import subprocess
 
+from charmhelpers.core.strutils import BasicStringComparator
+
+
+UBUNTU_RELEASES = (
+    'lucid',
+    'maverick',
+    'natty',
+    'oneiric',
+    'precise',
+    'quantal',
+    'raring',
+    'saucy',
+    'trusty',
+    'utopic',
+    'vivid',
+    'wily',
+    'xenial',
+    'yakkety',
+    'zesty',
+)
+
+
+class CompareHostReleases(BasicStringComparator):
+    """Provide comparisons of Ubuntu releases.
+
+    Use in the form of
+
+    if CompareHostReleases(release) > 'trusty':
+        # do something with mitaka
+    """
+    _list = UBUNTU_RELEASES
+
 
 def service_available(service_name):
     """Determine whether a system service is available"""

hooks/charmhelpers/core/strutils.py

@@ -68,3 +68,56 @@ def bytes_from_string(value):
         msg = "Unable to interpret string value '%s' as bytes" % (value)
         raise ValueError(msg)
     return int(matches.group(1)) * (1024 ** BYTE_POWER[matches.group(2)])
+
+
+class BasicStringComparator(object):
+    """Provides a class that will compare strings from an iterator type object.
+    Used to provide > and < comparisons on strings that may not necessarily be
+    alphanumerically ordered.  e.g. OpenStack or Ubuntu releases AFTER the
+    z-wrap.
+    """
+
+    _list = None
+
+    def __init__(self, item):
+        if self._list is None:
+            raise Exception("Must define the _list in the class definition!")
+        try:
+            self.index = self._list.index(item)
+        except Exception:
+            raise KeyError("Item '{}' is not in list '{}'"
+                           .format(item, self._list))
+
+    def __eq__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index == self._list.index(other)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __lt__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index < self._list.index(other)
+
+    def __ge__(self, other):
+        return not self.__lt__(other)
+
+    def __gt__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index > self._list.index(other)
+
+    def __le__(self, other):
+        return not self.__gt__(other)
+
+    def __str__(self):
+        """Always give back the item at the index so it can be used in
+        comparisons like:
+
+        s_mitaka = CompareOpenStack('mitaka')
+        s_newton = CompareOpenstack('newton')
+
+        assert s_newton > s_mitaka
+
+        @returns: <string>
+        """
+        return self._list[self.index]

hooks/cinder_contexts.py

@@ -36,7 +36,8 @@ class CephSubordinateContext(OSContextGenerator):
         if not is_relation_made('ceph', 'key'):
             return {}
         service = service_name()
-        if get_os_codename_package('cinder-common') >= "icehouse":
+        os_codename = get_os_codename_package('cinder-common')
+        if os_codename >= "icehouse":
             volume_driver = 'cinder.volume.drivers.rbd.RBDDriver'
         else:
             volume_driver = 'cinder.volume.driver.RBDDriver'

metadata.yaml

@@ -12,6 +12,7 @@ tags:
   - misc
 series:
   - xenial
+  - zesty
   - trusty
   - yakkety
 subordinate: true

tests/basic_deployment.py

@@ -84,8 +84,13 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
             'cinder:shared-db': 'percona-cluster:shared-db',
             'cinder:identity-service': 'keystone:identity-service',
             'cinder:amqp': 'rabbitmq-server:amqp',
-            'cinder:ceph': 'ceph:client',
         }
+        # If the release is less than ocata then add in the cinder <-> ceph
+        # relationship; it's not needed for ocata onwards as cinder gained the
+        # ability to have multiple backends, and in this test (cinder-ceph) we
+        # only want THIS backend.
+        if self._get_openstack_release() < self.xenial_ocata:
+            relations['cinder:ceph'] = 'ceph:client'
         super(CinderCephBasicDeployment, self)._add_relations(relations)
 
     def _configure_services(self):
@@ -202,12 +207,18 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
 
     def test_102_services(self):
         """Verify the expected services are running on the service units."""
+        if self._get_openstack_release() >= self.xenial_ocata:
+            cinder_services = ['apache2',
+                               'cinder-scheduler',
+                               'cinder-volume']
+        else:
+            cinder_services = ['cinder-api',
+                               'cinder-scheduler',
+                               'cinder-volume']
         services = {
             self.rabbitmq_sentry: ['rabbitmq-server'],
             self.keystone_sentry: ['keystone'],
-            self.cinder_sentry: ['cinder-api',
-                                 'cinder-scheduler',
-                                 'cinder-volume'],
+            self.cinder_sentry: cinder_services,
         }
 
         if self._get_openstack_release() < self.xenial_mitaka:
@@ -548,15 +559,11 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
 
         expected = {
             'DEFAULT': {
-                # XXX: Temporarily disabled use_syslog check, pending
-                #      resolution of https://bugs.launchpad.net/bugs/1604575
-                # 'use_syslog': 'False',
+                'use_syslog': 'False',
                 'debug': 'False',
                 'verbose': 'False',
                 'iscsi_helper': 'tgtadm',
-                'volume_group': 'cinder-volumes',
                 'auth_strategy': 'keystone',
-                'volumes_dir': '/var/lib/cinder/volumes',
                 'enabled_backends': 'cinder-ceph'
             },
             'cinder-ceph': {
@@ -564,8 +571,11 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
                 'volume_driver': 'cinder.volume.drivers.rbd.RBDDriver',
                 'rbd_pool': 'cinder-ceph',
                 'rbd_user': 'cinder-ceph'
-            }
+            },
         }
+        if self._get_openstack_release() < self.xenial_ocata:
+            expected['DEFAULT']['volume_group'] = 'cinder-volumes'
+            expected['DEFAULT']['volumes_dir'] = '/var/lib/cinder/volumes'
 
         expected_rmq = {
             'rabbit_userid': 'cinder',
@@ -644,6 +654,11 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
         if 'cinder-ceph' not in expected_pools:
             expected_pools.append('cinder-ceph')
 
+        if self._get_openstack_release() >= self.xenial_ocata:
+            # No cinder after mitaka because we don't use the relation in this
+            # test
+            expected_pools.remove('cinder')
+
         results = []
         sentries = [
             self.ceph0_sentry,
@@ -740,6 +755,7 @@ class CinderCephBasicDeployment(OpenStackAmuletDeployment):
     def test_499_ceph_cmds_exit_zero(self):
         """Check basic functionality of ceph cli commands against
         all ceph units, and the cinder-ceph unit."""
+        u.log.debug('Checking exit values are 0 on ceph commands')
         sentry_units = [
             self.cinder_ceph_sentry,
             self.ceph0_sentry,

tests/charmhelpers/contrib/openstack/amulet/utils.py

@@ -40,6 +40,7 @@ from charmhelpers.contrib.amulet.utils import (
     AmuletUtils
 )
 from charmhelpers.core.decorators import retry_on_exception
+from charmhelpers.core.host import CompareHostReleases
 
 DEBUG = logging.DEBUG
 ERROR = logging.ERROR
@@ -1255,7 +1256,7 @@ class OpenStackAmuletUtils(AmuletUtils):
         contents = self.file_contents_safe(sentry_unit, '/etc/memcached.conf',
                                            fatal=True)
         ubuntu_release, _ = self.run_cmd_unit(sentry_unit, 'lsb_release -cs')
-        if ubuntu_release <= 'trusty':
+        if CompareHostReleases(ubuntu_release) <= 'trusty':
             memcache_listen_addr = 'ip6-localhost'
         else:
             memcache_listen_addr = '::1'

tests/charmhelpers/core/host.py

@@ -45,6 +45,7 @@ if __platform__ == "ubuntu":
         add_new_group,
         lsb_release,
         cmp_pkgrevno,
+        CompareHostReleases,
     )  # flake8: noqa -- ignore F401 for this import
 elif __platform__ == "centos":
     from charmhelpers.core.host_factory.centos import (
@@ -52,6 +53,7 @@ elif __platform__ == "centos":
         add_new_group,
         lsb_release,
         cmp_pkgrevno,
+        CompareHostReleases,
     )  # flake8: noqa -- ignore F401 for this import
 
 UPDATEDB_PATH = '/etc/updatedb.conf'

tests/charmhelpers/core/host_factory/centos.py

@@ -2,6 +2,22 @@ import subprocess
 import yum
 import os
 
+from charmhelpers.core.strutils import BasicStringComparator
+
+
+class CompareHostReleases(BasicStringComparator):
+    """Provide comparisons of Host releases.
+
+    Use in the form of
+
+    if CompareHostReleases(release) > 'trusty':
+        # do something with mitaka
+    """
+
+    def __init__(self, item):
+        raise NotImplementedError(
+            "CompareHostReleases() is not implemented for CentOS")
+
 
 def service_available(service_name):
     # """Determine whether a system service is available."""

tests/charmhelpers/core/host_factory/ubuntu.py

@@ -1,5 +1,37 @@
 import subprocess
 
+from charmhelpers.core.strutils import BasicStringComparator
+
+
+UBUNTU_RELEASES = (
+    'lucid',
+    'maverick',
+    'natty',
+    'oneiric',
+    'precise',
+    'quantal',
+    'raring',
+    'saucy',
+    'trusty',
+    'utopic',
+    'vivid',
+    'wily',
+    'xenial',
+    'yakkety',
+    'zesty',
+)
+
+
+class CompareHostReleases(BasicStringComparator):
+    """Provide comparisons of Ubuntu releases.
+
+    Use in the form of
+
+    if CompareHostReleases(release) > 'trusty':
+        # do something with mitaka
+    """
+    _list = UBUNTU_RELEASES
+
 
 def service_available(service_name):
     """Determine whether a system service is available"""

tests/charmhelpers/core/strutils.py

@@ -68,3 +68,56 @@ def bytes_from_string(value):
         msg = "Unable to interpret string value '%s' as bytes" % (value)
         raise ValueError(msg)
     return int(matches.group(1)) * (1024 ** BYTE_POWER[matches.group(2)])
+
+
+class BasicStringComparator(object):
+    """Provides a class that will compare strings from an iterator type object.
+    Used to provide > and < comparisons on strings that may not necessarily be
+    alphanumerically ordered.  e.g. OpenStack or Ubuntu releases AFTER the
+    z-wrap.
+    """
+
+    _list = None
+
+    def __init__(self, item):
+        if self._list is None:
+            raise Exception("Must define the _list in the class definition!")
+        try:
+            self.index = self._list.index(item)
+        except Exception:
+            raise KeyError("Item '{}' is not in list '{}'"
+                           .format(item, self._list))
+
+    def __eq__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index == self._list.index(other)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __lt__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index < self._list.index(other)
+
+    def __ge__(self, other):
+        return not self.__lt__(other)
+
+    def __gt__(self, other):
+        assert isinstance(other, str) or isinstance(other, self.__class__)
+        return self.index > self._list.index(other)
+
+    def __le__(self, other):
+        return not self.__gt__(other)
+
+    def __str__(self):
+        """Always give back the item at the index so it can be used in
+        comparisons like:
+
+        s_mitaka = CompareOpenStack('mitaka')
+        s_newton = CompareOpenstack('newton')
+
+        assert s_newton > s_mitaka
+
+        @returns: <string>
+        """
+        return self._list[self.index]

tests/charmhelpers/osplatform.py

@@ -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))

tox.ini

@@ -14,7 +14,7 @@ install_command =
   pip install --allow-unverified python-apt {opts} {packages}
 commands = ostestr {posargs}
 whitelist_externals = juju
-passenv = HOME TERM AMULET_*
+passenv = HOME TERM AMULET_* CS_API_*
 
 [testenv:py27]
 basepython = python2.7