Fix alphanumeric comparisons for openstack and ubuntu releases

- sync charmhelpers with fix-alpha helpers
- fix up code where the alpha comparisons are done

Change-Id: I10e3e689aba490118b84b6b9e58df1ba5632d07d
Related-Bug: #1659575

charm-helpers-tests.yaml

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

hooks/ceph.py

@@ -15,19 +15,23 @@ import sys
 from charmhelpers.contrib.storage.linux.utils import (
     is_block_device,
     zap_disk,
-    is_device_mounted)
+    is_device_mounted,
+)
 from charmhelpers.core.host import (
     mkdir,
     chownr,
     service_restart,
     lsb_release,
-    cmp_pkgrevno)
+    cmp_pkgrevno,
+    CompareHostReleases,
+)
 from charmhelpers.core.hookenv import (
     log,
     ERROR,
     cached,
     status_set,
-    WARNING)
+    WARNING,
+)
 from charmhelpers.fetch import (
     apt_cache
 )
@@ -403,7 +407,7 @@ def upgrade_key_caps(key, caps):
 
 @cached
 def systemd():
-    return (lsb_release()['DISTRIB_CODENAME'] >= 'vivid')
+    return CompareHostReleases(lsb_release()['DISTRIB_CODENAME']) >= 'vivid'
 
 
 def bootstrap_monitor_cluster(secret):

hooks/charmhelpers/contrib/hardening/apache/checks/config.py

@@ -26,6 +26,7 @@ from charmhelpers.contrib.hardening.audits.file import (
     DirectoryPermissionAudit,
     NoReadWriteForOther,
     TemplatedFile,
+    DeletedFile
 )
 from charmhelpers.contrib.hardening.audits.apache import DisabledModuleAudit
 from charmhelpers.contrib.hardening.apache import TEMPLATES_DIR
@@ -52,13 +53,13 @@ def get_audits():
                                    'mods-available/alias.conf'),
                       context,
                       TEMPLATES_DIR,
-                      mode=0o0755,
+                      mode=0o0640,
                       user='root',
                       service_actions=[{'service': 'apache2',
                                         'actions': ['restart']}]),
 
         TemplatedFile(os.path.join(settings['common']['apache_dir'],
-                                   'conf-enabled/hardening.conf'),
+                                   'conf-enabled/99-hardening.conf'),
                       context,
                       TEMPLATES_DIR,
                       mode=0o0640,
@@ -69,11 +70,13 @@ def get_audits():
         DirectoryPermissionAudit(settings['common']['apache_dir'],
                                  user='root',
                                  group='root',
-                                 mode=0o640),
+                                 mode=0o0750),
 
         DisabledModuleAudit(settings['hardening']['modules_to_disable']),
 
         NoReadWriteForOther(settings['common']['apache_dir']),
+
+        DeletedFile(['/var/www/html/index.html'])
     ]
 
     return audits
@@ -94,5 +97,4 @@ class ApacheConfContext(object):
         ctxt['apache_version'] = re.search(r'.+version: Apache/(.+?)\s.+',
                                            out).group(1)
         ctxt['apache_icondir'] = '/usr/share/apache2/icons/'
-        ctxt['traceenable'] = settings['hardening']['traceenable']
         return ctxt

hooks/charmhelpers/contrib/hardening/apache/templates/99-hardening.conf

@@ -4,15 +4,29 @@
 ###############################################################################
 
 <Location / >
-  <LimitExcept {{ allowed_http_methods }} > 
+  <LimitExcept {{ allowed_http_methods }} >
     # http://httpd.apache.org/docs/2.4/upgrading.html
     {% if apache_version > '2.2' -%}
     Require all granted
     {% else -%}
-    Order Allow,Deny 
-    Deny from all 
+    Order Allow,Deny
+    Deny from all
     {% endif %}
   </LimitExcept>
 </Location>
 
+<Directory />
+    Options -Indexes -FollowSymLinks
+    AllowOverride None
+</Directory>
+
+<Directory /var/www/>
+    Options -Indexes -FollowSymLinks
+    AllowOverride None
+</Directory>
+
 TraceEnable {{ traceenable }}
+ServerTokens {{ servertokens }}
+
+SSLHonorCipherOrder {{ honor_cipher_order }}
+SSLCipherSuite {{ cipher_suite }}

hooks/charmhelpers/contrib/hardening/audits/__init__.py

@@ -49,13 +49,6 @@ class BaseAudit(object):  # NO-QA
 
         # Invoke the callback if there is one.
         if hasattr(self.unless, '__call__'):
-            results = self.unless()
-            if results:
-                return False
-            else:
-                return True
+            return not self.unless()
 
-        if self.unless:
-            return False
-        else:
-            return True
+        return not self.unless

hooks/charmhelpers/contrib/hardening/defaults/apache.yaml

@@ -10,4 +10,7 @@ common:
 hardening:
     traceenable: 'off'
     allowed_http_methods: "GET POST"
-    modules_to_disable: [ cgi, cgid ]
+    modules_to_disable: [ cgi, cgid ]
+    servertokens: 'Prod'
+    honor_cipher_order: 'on'
+    cipher_suite: 'ALL:+MEDIUM:+HIGH:!LOW:!MD5:!RC4:!eNULL:!aNULL:!3DES'

hooks/charmhelpers/contrib/hardening/defaults/apache.yaml.schema

@@ -7,3 +7,6 @@ common:
 hardening:
     allowed_http_methods:
     modules_to_disable:
+    servertokens:
+    honor_cipher_order:
+    cipher_suite:

hooks/charmhelpers/contrib/hardening/defaults/os.yaml

@@ -58,6 +58,7 @@ security:
         rsync
     kernel_enable_module_loading: True  # (type:boolean)
     kernel_enable_core_dump: False  # (type:boolean)
+    ssh_tmout: 300
 
 sysctl:
     kernel_secure_sysrq: 244  # 4 + 16 + 32 + 64 + 128

hooks/charmhelpers/contrib/hardening/defaults/os.yaml.schema

@@ -34,6 +34,7 @@ security:
     packages_list:
     kernel_enable_module_loading:
     kernel_enable_core_dump:
+    ssh_tmout:
 sysctl:
     kernel_secure_sysrq:
     kernel_enable_sysrq:

hooks/charmhelpers/contrib/hardening/host/checks/profile.py

@@ -25,7 +25,6 @@ def get_audits():
     audits = []
 
     settings = utils.get_settings('os')
-
     # If core dumps are not enabled, then don't allow core dumps to be
     # created as they may contain sensitive information.
     if not settings['security']['kernel_enable_core_dump']:
@@ -33,11 +32,18 @@ def get_audits():
                                     ProfileContext(),
                                     template_dir=TEMPLATES_DIR,
                                     mode=0o0755, user='root', group='root'))
+    if settings['security']['ssh_tmout']:
+        audits.append(TemplatedFile('/etc/profile.d/99-hardening.sh',
+                                    ProfileContext(),
+                                    template_dir=TEMPLATES_DIR,
+                                    mode=0o0644, user='root', group='root'))
     return audits
 
 
 class ProfileContext(object):
 
     def __call__(self):
-        ctxt = {}
+        settings = utils.get_settings('os')
+        ctxt = {'ssh_tmout':
+                settings['security']['ssh_tmout']}
         return ctxt

hooks/charmhelpers/contrib/hardening/host/templates/99-hardening.sh

@@ -0,0 +1,5 @@
+TMOUT={{ tmout }}
+readonly TMOUT
+export TMOUT
+
+readonly HISTFILE

hooks/charmhelpers/contrib/hardening/ssh/checks/config.py

@@ -27,7 +27,10 @@ from charmhelpers.fetch import (
     apt_install,
     apt_update,
 )
-from charmhelpers.core.host import lsb_release
+from charmhelpers.core.host import (
+    lsb_release,
+    CompareHostReleases,
+)
 from charmhelpers.contrib.hardening.audits.file import (
     TemplatedFile,
     FileContentAudit,
@@ -68,7 +71,8 @@ class SSHConfigContext(object):
                    'weak': default + ',hmac-sha1'}
 
         # Use newer ciphers on Ubuntu Trusty and above
-        if lsb_release()['DISTRIB_CODENAME'].lower() >= 'trusty':
+        _release = lsb_release()['DISTRIB_CODENAME'].lower()
+        if CompareHostReleases(_release) >= 'trusty':
             log("Detected Ubuntu 14.04 or newer, using new macs", level=DEBUG)
             macs = macs_66
 
@@ -96,7 +100,8 @@ class SSHConfigContext(object):
                   'weak': weak}
 
         # Use newer kex on Ubuntu Trusty and above
-        if lsb_release()['DISTRIB_CODENAME'].lower() >= 'trusty':
+        _release = lsb_release()['DISTRIB_CODENAME'].lower()
+        if CompareHostReleases(_release) >= 'trusty':
             log('Detected Ubuntu 14.04 or newer, using new key exchange '
                 'algorithms', level=DEBUG)
             kex = kex_66
@@ -119,7 +124,8 @@ class SSHConfigContext(object):
                       'weak': default + ',aes256-cbc,aes192-cbc,aes128-cbc'}
 
         # Use newer ciphers on ubuntu Trusty and above
-        if lsb_release()['DISTRIB_CODENAME'].lower() >= 'trusty':
+        _release = lsb_release()['DISTRIB_CODENAME'].lower()
+        if CompareHostReleases(_release) >= 'trusty':
             log('Detected Ubuntu 14.04 or newer, using new ciphers',
                 level=DEBUG)
             cipher = ciphers_66
@@ -291,7 +297,8 @@ class SSHConfigFileContentAudit(FileContentAudit):
         self.fail_cases = []
         settings = utils.get_settings('ssh')
 
-        if lsb_release()['DISTRIB_CODENAME'].lower() >= 'trusty':
+        _release = lsb_release()['DISTRIB_CODENAME'].lower()
+        if CompareHostReleases(_release) >= 'trusty':
             if not settings['server']['weak_hmac']:
                 self.pass_cases.append(r'^MACs.+,hmac-ripemd160$')
             else:
@@ -364,7 +371,8 @@ class SSHDConfigFileContentAudit(FileContentAudit):
         self.fail_cases = []
         settings = utils.get_settings('ssh')
 
-        if lsb_release()['DISTRIB_CODENAME'].lower() >= 'trusty':
+        _release = lsb_release()['DISTRIB_CODENAME'].lower()
+        if CompareHostReleases(_release) >= 'trusty':
             if not settings['server']['weak_hmac']:
                 self.pass_cases.append(r'^MACs.+,hmac-ripemd160$')
             else:

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/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/contrib/storage/linux/ceph.py

@@ -987,18 +987,20 @@ def ensure_ceph_storage(service, pool, rbd_img, sizemb, mount_point,
             service_start(svc)
 
 
-def ensure_ceph_keyring(service, user=None, group=None, relation='ceph'):
+def ensure_ceph_keyring(service, user=None, group=None,
+                        relation='ceph', key=None):
     """Ensures a ceph keyring is created for a named service and optionally
     ensures user and group ownership.
 
-    Returns False if no ceph key is available in relation state.
+    @returns boolean: Flag to indicate whether a key was successfully written
+                      to disk based on either relation data or a supplied key
     """
-    key = None
-    for rid in relation_ids(relation):
-        for unit in related_units(rid):
-            key = relation_get('key', rid=rid, unit=unit)
-            if key:
-                break
+    if not key:
+        for rid in relation_ids(relation):
+            for unit in related_units(rid):
+                key = relation_get('key', rid=rid, unit=unit)
+                if key:
+                    break
 
     if not key:
         return False

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/utils.py

@@ -15,20 +15,22 @@ from charmhelpers.core.hookenv import (
     config,
     status_set,
     network_get_primary_address,
-    log, DEBUG,
+    log,
+    DEBUG,
 )
 from charmhelpers.fetch import (
     apt_install,
-    filter_installed_packages
+    filter_installed_packages,
 )
 
 from charmhelpers.core.host import (
-    lsb_release
+    lsb_release,
+    CompareHostReleases,
 )
 
 from charmhelpers.contrib.network.ip import (
     get_address_in_network,
-    get_ipv6_addr
+    get_ipv6_addr,
 )
 
 try:
@@ -141,6 +143,7 @@ def get_network_addrs(config_opt):
 
 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")

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