text: # Copyright 2014-2015 Canonical Limited.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #  http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  # Common python helper functions used for OpenStack charms.
  from collections import OrderedDict
  from functools import wraps
  
  import subprocess
  import json
  import os
  import sys
  import re
  import itertools
  import functools
  
  import six
  import traceback
  import uuid
  import yaml
  
  from charmhelpers import deprecate
  
  from charmhelpers.contrib.network import ip
  
  from charmhelpers.core import unitdata
  
  from charmhelpers.core.hookenv import (
      action_fail,
      action_set,
      config,
      log as juju_log,
      charm_dir,
      INFO,
      ERROR,
      related_units,
      relation_ids,
      relation_set,
      status_set,
      hook_name,
      application_version_set,
      cached,
      leader_set,
      leader_get,
  )
  
  from charmhelpers.core.strutils import (
      BasicStringComparator,
      bool_from_string,
  )
  
  from charmhelpers.contrib.storage.linux.lvm import (
      deactivate_lvm_volume_group,
      is_lvm_physical_volume,
      remove_lvm_physical_volume,
  )
  
  from charmhelpers.contrib.network.ip import (
      get_ipv6_addr,
      is_ipv6,
      port_has_listener,
  )
  
  from charmhelpers.core.host import (
      lsb_release,
      mounts,
      umount,
      service_running,
      service_pause,
      service_resume,
      service_stop,
      service_start,
      restart_on_change_helper,
  )
  from charmhelpers.fetch import (
      apt_cache,
      import_key as fetch_import_key,
      add_source as fetch_add_source,
      SourceConfigError,
      GPGKeyError,
      get_upstream_version,
      filter_missing_packages,
      ubuntu_apt_pkg as apt,
  )
  
  from charmhelpers.fetch.snap import (
      snap_install,
      snap_refresh,
      valid_snap_channel,
  )
  
  from charmhelpers.contrib.storage.linux.utils import is_block_device, zap_disk
  from charmhelpers.contrib.storage.linux.loopback import ensure_loopback_device
  from charmhelpers.contrib.openstack.exceptions import OSContextError
  from charmhelpers.contrib.openstack.policyd import (
      policyd_status_message_prefix,
      POLICYD_CONFIG_NAME,
  )
  
  CLOUD_ARCHIVE_URL = "http://ubuntu-cloud.archive.canonical.com/ubuntu"
  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',
      'queens',
      'rocky',
      'stein',
      'train',
      'ussuri',
  )
  
  UBUNTU_OPENSTACK_RELEASE = OrderedDict([
      ('oneiric', 'diablo'),
      ('precise', 'essex'),
      ('quantal', 'folsom'),
      ('raring', 'grizzly'),
      ('saucy', 'havana'),
      ('trusty', 'icehouse'),
      ('utopic', 'juno'),
      ('vivid', 'kilo'),
      ('wily', 'liberty'),
      ('xenial', 'mitaka'),
      ('yakkety', 'newton'),
      ('zesty', 'ocata'),
      ('artful', 'pike'),
      ('bionic', 'queens'),
      ('cosmic', 'rocky'),
      ('disco', 'stein'),
      ('eoan', 'train'),
      ('focal', 'ussuri'),
  ])
  
  
  OPENSTACK_CODENAMES = OrderedDict([
      ('2011.2', 'diablo'),
      ('2012.1', 'essex'),
      ('2012.2', 'folsom'),
      ('2013.1', 'grizzly'),
      ('2013.2', 'havana'),
      ('2014.1', 'icehouse'),
      ('2014.2', 'juno'),
      ('2015.1', 'kilo'),
      ('2015.2', 'liberty'),
      ('2016.1', 'mitaka'),
      ('2016.2', 'newton'),
      ('2017.1', 'ocata'),
      ('2017.2', 'pike'),
      ('2018.1', 'queens'),
      ('2018.2', 'rocky'),
      ('2019.1', 'stein'),
      ('2019.2', 'train'),
      ('2020.1', 'ussuri'),
  ])
  
  # The ugly duckling - must list releases oldest to newest
  SWIFT_CODENAMES = OrderedDict([
      ('diablo',
          ['1.4.3']),
      ('essex',
          ['1.4.8']),
      ('folsom',
          ['1.7.4']),
      ('grizzly',
          ['1.7.6', '1.7.7', '1.8.0']),
      ('havana',
          ['1.9.0', '1.9.1', '1.10.0']),
      ('icehouse',
          ['1.11.0', '1.12.0', '1.13.0', '1.13.1']),
      ('juno',
          ['2.0.0', '2.1.0', '2.2.0']),
      ('kilo',
          ['2.2.1', '2.2.2']),
      ('liberty',
          ['2.3.0', '2.4.0', '2.5.0']),
      ('mitaka',
          ['2.5.0', '2.6.0', '2.7.0']),
      ('newton',
          ['2.8.0', '2.9.0', '2.10.0']),
      ('ocata',
          ['2.11.0', '2.12.0', '2.13.0']),
      ('pike',
          ['2.13.0', '2.15.0']),
      ('queens',
          ['2.16.0', '2.17.0']),
      ('rocky',
          ['2.18.0', '2.19.0']),
      ('stein',
          ['2.20.0', '2.21.0']),
      ('train',
          ['2.22.0', '2.23.0']),
      ('ussuri',
          ['2.24.0']),
  ])
  
  # >= Liberty version->codename mapping
  PACKAGE_CODENAMES = {
      'nova-common': OrderedDict([
          ('12', 'liberty'),
          ('13', 'mitaka'),
          ('14', 'newton'),
          ('15', 'ocata'),
          ('16', 'pike'),
          ('17', 'queens'),
          ('18', 'rocky'),
          ('19', 'stein'),
          ('20', 'train'),
          ('21', 'ussuri'),
      ]),
      'neutron-common': OrderedDict([
          ('7', 'liberty'),
          ('8', 'mitaka'),
          ('9', 'newton'),
          ('10', 'ocata'),
          ('11', 'pike'),
          ('12', 'queens'),
          ('13', 'rocky'),
          ('14', 'stein'),
          ('15', 'train'),
          ('16', 'ussuri'),
      ]),
      'cinder-common': OrderedDict([
          ('7', 'liberty'),
          ('8', 'mitaka'),
          ('9', 'newton'),
          ('10', 'ocata'),
          ('11', 'pike'),
          ('12', 'queens'),
          ('13', 'rocky'),
          ('14', 'stein'),
          ('15', 'train'),
          ('16', 'ussuri'),
      ]),
      'keystone': OrderedDict([
          ('8', 'liberty'),
          ('9', 'mitaka'),
          ('10', 'newton'),
          ('11', 'ocata'),
          ('12', 'pike'),
          ('13', 'queens'),
          ('14', 'rocky'),
          ('15', 'stein'),
          ('16', 'train'),
          ('17', 'ussuri'),
      ]),
      'horizon-common': OrderedDict([
          ('8', 'liberty'),
          ('9', 'mitaka'),
          ('10', 'newton'),
          ('11', 'ocata'),
          ('12', 'pike'),
          ('13', 'queens'),
          ('14', 'rocky'),
          ('15', 'stein'),
          ('16', 'train'),
          ('17', 'ussuri'),
      ]),
      'ceilometer-common': OrderedDict([
          ('5', 'liberty'),
          ('6', 'mitaka'),
          ('7', 'newton'),
          ('8', 'ocata'),
          ('9', 'pike'),
          ('10', 'queens'),
          ('11', 'rocky'),
          ('12', 'stein'),
          ('13', 'train'),
          ('14', 'ussuri'),
      ]),
      'heat-common': OrderedDict([
          ('5', 'liberty'),
          ('6', 'mitaka'),
          ('7', 'newton'),
          ('8', 'ocata'),
          ('9', 'pike'),
          ('10', 'queens'),
          ('11', 'rocky'),
          ('12', 'stein'),
          ('13', 'train'),
          ('14', 'ussuri'),
      ]),
      'glance-common': OrderedDict([
          ('11', 'liberty'),
          ('12', 'mitaka'),
          ('13', 'newton'),
          ('14', 'ocata'),
          ('15', 'pike'),
          ('16', 'queens'),
          ('17', 'rocky'),
          ('18', 'stein'),
          ('19', 'train'),
          ('20', 'ussuri'),
      ]),
      'openstack-dashboard': OrderedDict([
          ('8', 'liberty'),
          ('9', 'mitaka'),
          ('10', 'newton'),
          ('11', 'ocata'),
          ('12', 'pike'),
          ('13', 'queens'),
          ('14', 'rocky'),
          ('15', 'stein'),
          ('16', 'train'),
          ('17', 'ussuri'),
      ]),
  }
  
  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)
  
  
  def get_installed_semantic_versioned_packages():
      '''Get a list of installed packages which have OpenStack semantic versioning
  
      :returns List of installed packages
      :rtype: [pkg1, pkg2, ...]
      '''
      return filter_missing_packages(PACKAGE_CODENAMES.keys())
  
  
  def get_os_codename_install_source(src):
      '''Derive OpenStack release codename from a given installation source.'''
      ubuntu_rel = lsb_release()['DISTRIB_CODENAME']
      rel = ''
      if src is None:
          return rel
      if src in ['distro', 'distro-proposed', 'proposed']:
          try:
              rel = UBUNTU_OPENSTACK_RELEASE[ubuntu_rel]
          except KeyError:
              e = 'Could not derive openstack release for '\
                  'this Ubuntu release: %s' % ubuntu_rel
              error_out(e)
          return rel
  
      if src.startswith('cloud:'):
          ca_rel = src.split(':')[1]
          ca_rel = ca_rel.split('-')[1].split('/')[0]
          return ca_rel
  
      # Best guess match based on deb string provided
      if (src.startswith('deb') or
              src.startswith('ppa') or
              src.startswith('snap')):
          for v in OPENSTACK_CODENAMES.values():
              if v in src:
                  return v
  
  
  def get_os_version_install_source(src):
      codename = get_os_codename_install_source(src)
      return get_os_version_codename(codename)
  
  
  def get_os_codename_version(vers):
      '''Determine OpenStack codename from version number.'''
      try:
          return OPENSTACK_CODENAMES[vers]
      except KeyError:
          e = 'Could not determine OpenStack codename for version %s' % vers
          error_out(e)
  
  
  def get_os_version_codename(codename, version_map=OPENSTACK_CODENAMES):
      '''Determine OpenStack version number from codename.'''
      for k, v in six.iteritems(version_map):
          if v == codename:
              return k
      e = 'Could not derive OpenStack version for '\
          'codename: %s' % codename
      error_out(e)
  
  
  def get_os_version_codename_swift(codename):
      '''Determine OpenStack version number of swift from codename.'''
      for k, v in six.iteritems(SWIFT_CODENAMES):
          if k == codename:
              return v[-1]
      e = 'Could not derive swift version for '\
          'codename: %s' % codename
      error_out(e)
  
  
  def get_swift_codename(version):
      '''Determine OpenStack codename that corresponds to swift version.'''
      codenames = [k for k, v in six.iteritems(SWIFT_CODENAMES) if version in v]
  
      if len(codenames) > 1:
          # If more than one release codename contains this version we determine
          # the actual codename based on the highest available install source.
          for codename in reversed(codenames):
              releases = UBUNTU_OPENSTACK_RELEASE
              release = [k for k, v in six.iteritems(releases) if codename in v]
              ret = subprocess.check_output(['apt-cache', 'policy', 'swift'])
              if six.PY3:
                  ret = ret.decode('UTF-8')
              if codename in ret or release[0] in ret:
                  return codename
      elif len(codenames) == 1:
          return codenames[0]
  
      # NOTE: fallback - attempt to match with just major.minor version
      match = re.match(r'^(\d+)\.(\d+)', version)
      if match:
          major_minor_version = match.group(0)
          for codename, versions in six.iteritems(SWIFT_CODENAMES):
              for release_version in versions:
                  if release_version.startswith(major_minor_version):
                      return codename
  
      return None
  
  
  def get_os_codename_package(package, fatal=True):
      '''Derive OpenStack release codename from an installed package.'''
  
      if snap_install_requested():
          cmd = ['snap', 'list', package]
          try:
              out = subprocess.check_output(cmd)
              if six.PY3:
                  out = out.decode('UTF-8')
          except subprocess.CalledProcessError:
              return None
          lines = out.split('\n')
          for line in lines:
              if package in line:
                  # Second item in list is Version
                  return line.split()[1]
  
      cache = apt_cache()
  
      try:
          pkg = cache[package]
      except Exception:
          if not fatal:
              return None
          # the package is unknown to the current apt cache.
          e = 'Could not determine version of package with no installation '\
              'candidate: %s' % package
          error_out(e)
  
      if not pkg.current_ver:
          if not fatal:
              return None
          # package is known, but no version is currently installed.
          e = 'Could not determine version of uninstalled package: %s' % package
          error_out(e)
  
      vers = apt.upstream_version(pkg.current_ver.ver_str)
      if 'swift' in pkg.name:
          # Fully x.y.z match for swift versions
          match = re.match(r'^(\d+)\.(\d+)\.(\d+)', vers)
      else:
          # x.y match only for 20XX.X
          # and ignore patch level for other packages
          match = re.match(r'^(\d+)\.(\d+)', vers)
  
      if match:
          vers = match.group(0)
  
      # Generate a major version number for newer semantic
      # versions of openstack projects
      major_vers = vers.split('.')[0]
      # >= Liberty independent project versions
      if (package in PACKAGE_CODENAMES and
              major_vers in PACKAGE_CODENAMES[package]):
          return PACKAGE_CODENAMES[package][major_vers]
      else:
          # < Liberty co-ordinated project versions
          try:
              if 'swift' in pkg.name:
                  return get_swift_codename(vers)
              else:
                  return OPENSTACK_CODENAMES[vers]
          except KeyError:
              if not fatal:
                  return None
              e = 'Could not determine OpenStack codename for version %s' % vers
              error_out(e)
  
  
  def get_os_version_package(pkg, fatal=True):
      '''Derive OpenStack version number from an installed package.'''
      codename = get_os_codename_package(pkg, fatal=fatal)
  
      if not codename:
          return None
  
      if 'swift' in pkg:
          vers_map = SWIFT_CODENAMES
          for cname, version in six.iteritems(vers_map):
              if cname == codename:
                  return version[-1]
      else:
          vers_map = OPENSTACK_CODENAMES
          for version, cname in six.iteritems(vers_map):
              if cname == codename:
                  return version
      # e = "Could not determine OpenStack version for package: %s" % pkg
      # error_out(e)
  
  
  # Module local cache variable for the os_release.
  _os_rel = None
  
  
  def reset_os_release():
      '''Unset the cached os_release version'''
      global _os_rel
      _os_rel = None
  
  
  def os_release(package, base=None, reset_cache=False):
      '''
      Returns OpenStack release codename from a cached global.
  
      If reset_cache then unset the cached os_release version and return the
      freshly determined version.
  
      If the codename can not be determined from either an installed package or
      the installation source, the earliest release supported by the charm should
      be returned.
      '''
      if not base:
          base = UBUNTU_OPENSTACK_RELEASE[lsb_release()['DISTRIB_CODENAME']]
      global _os_rel
      if reset_cache:
          reset_os_release()
      if _os_rel:
          return _os_rel
      _os_rel = (
          get_os_codename_package(package, fatal=False) or
          get_os_codename_install_source(config('openstack-origin')) or
          base)
      return _os_rel
  
  
  @deprecate("moved to charmhelpers.fetch.import_key()", "2017-07", log=juju_log)
  def import_key(keyid):
      """Import a key, either ASCII armored, or a GPG key id.
  
      @param keyid: the key in ASCII armor format, or a GPG key id.
      @raises SystemExit() via sys.exit() on failure.
      """
      try:
          return fetch_import_key(keyid)
      except GPGKeyError as e:
          error_out("Could not import key: {}".format(str(e)))
  
  
  def get_source_and_pgp_key(source_and_key):
      """Look for a pgp key ID or ascii-armor key in the given input.
  
      :param source_and_key: Sting, "source_spec|keyid" where '|keyid' is
          optional.
      :returns (source_spec, key_id OR None) as a tuple.  Returns None for key_id
          if there was no '|' in the source_and_key string.
      """
      try:
          source, key = source_and_key.split('|', 2)
          return source, key or None
      except ValueError:
          return source_and_key, None
  
  
  @deprecate("use charmhelpers.fetch.add_source() instead.",
             "2017-07", log=juju_log)
  def configure_installation_source(source_plus_key):
      """Configure an installation source.
  
      The functionality is provided by charmhelpers.fetch.add_source()
      The difference between the two functions is that add_source() signature
      requires the key to be passed directly, whereas this function passes an
      optional key by appending '|<key>' to the end of the source specificiation
      'source'.
  
      Another difference from add_source() is that the function calls sys.exit(1)
      if the configuration fails, whereas add_source() raises
      SourceConfigurationError().  Another difference, is that add_source()
      silently fails (with a juju_log command) if there is no matching source to
      configure, whereas this function fails with a sys.exit(1)
  
      :param source: String_plus_key -- see above for details.
  
      Note that the behaviour on error is to log the error to the juju log and
      then call sys.exit(1).
      """
      if source_plus_key.startswith('snap'):
          # Do nothing for snap installs
          return
      # extract the key if there is one, denoted by a '|' in the rel
      source, key = get_source_and_pgp_key(source_plus_key)
  
      # handle the ordinary sources via add_source
      try:
          fetch_add_source(source, key, fail_invalid=True)
      except SourceConfigError as se:
          error_out(str(se))
  
  
  def config_value_changed(option):
      """
      Determine if config value changed since last call to this function.
      """
      hook_data = unitdata.HookData()
      with hook_data():
          db = unitdata.kv()
          current = config(option)
          saved = db.get(option)
          db.set(option, current)
          if saved is None:
              return False
          return current != saved
  
  
  def save_script_rc(script_path="scripts/scriptrc", **env_vars):
      """
      Write an rc file in the charm-delivered directory containing
      exported environment variables provided by env_vars. Any charm scripts run
      outside the juju hook environment can source this scriptrc to obtain
      updated config information necessary to perform health checks or
      service changes.
      """
      juju_rc_path = "%s/%s" % (charm_dir(), script_path)
      if not os.path.exists(os.path.dirname(juju_rc_path)):
          os.mkdir(os.path.dirname(juju_rc_path))
      with open(juju_rc_path, 'wt') as rc_script:
          rc_script.write(
              "#!/bin/bash\n")
          [rc_script.write('export %s=%s\n' % (u, p))
           for u, p in six.iteritems(env_vars) if u != "script_path"]
  
  
  def openstack_upgrade_available(package):
      """
      Determines if an OpenStack upgrade is available from installation
      source, based on version of installed package.
  
      :param package: str: Name of installed package.
  
      :returns: bool:    : Returns True if configured installation source offers
                           a newer version of package.
      """
  
      src = config('openstack-origin')
      cur_vers = get_os_version_package(package)
      if not cur_vers:
          # The package has not been installed yet do not attempt upgrade
          return False
      if "swift" in package:
          codename = get_os_codename_install_source(src)
          avail_vers = get_os_version_codename_swift(codename)
      else:
          try:
              avail_vers = get_os_version_install_source(src)
          except Exception:
              avail_vers = cur_vers
      apt.init()
      return apt.version_compare(avail_vers, cur_vers) >= 1
  
  
  def ensure_block_device(block_device):
      '''
      Confirm block_device, create as loopback if necessary.
  
      :param block_device: str: Full path of block device to ensure.
  
      :returns: str: Full path of ensured block device.
      '''
      _none = ['None', 'none', None]
      if (block_device in _none):
          error_out('prepare_storage(): Missing required input: block_device=%s.'
                    % block_device)
  
      if block_device.startswith('/dev/'):
          bdev = block_device
      elif block_device.startswith('/'):
          _bd = block_device.split('|')
          if len(_bd) == 2:
              bdev, size = _bd
          else:
              bdev = block_device
              size = DEFAULT_LOOPBACK_SIZE
          bdev = ensure_loopback_device(bdev, size)
      else:
          bdev = '/dev/%s' % block_device
  
      if not is_block_device(bdev):
          error_out('Failed to locate valid block device at %s' % bdev)
  
      return bdev
  
  
  def clean_storage(block_device):
      '''
      Ensures a block device is clean.  That is:
          - unmounted
          - any lvm volume groups are deactivated
          - any lvm physical device signatures removed
          - partition table wiped
  
      :param block_device: str: Full path to block device to clean.
      '''
      for mp, d in mounts():
          if d == block_device:
              juju_log('clean_storage(): %s is mounted @ %s, unmounting.' %
                       (d, mp), level=INFO)
              umount(mp, persist=True)
  
      if is_lvm_physical_volume(block_device):
          deactivate_lvm_volume_group(block_device)
          remove_lvm_physical_volume(block_device)
      else:
          zap_disk(block_device)
  
  
  is_ip = ip.is_ip
  ns_query = ip.ns_query
  get_host_ip = ip.get_host_ip
  get_hostname = ip.get_hostname
  
  
  def get_matchmaker_map(mm_file='/etc/oslo/matchmaker_ring.json'):
      mm_map = {}
      if os.path.isfile(mm_file):
          with open(mm_file, 'r') as f:
              mm_map = json.load(f)
      return mm_map
  
  
  def sync_db_with_multi_ipv6_addresses(database, database_user,
                                        relation_prefix=None):
      hosts = get_ipv6_addr(dynamic_only=False)
  
      if config('vip'):
          vips = config('vip').split()
          for vip in vips:
              if vip and is_ipv6(vip):
                  hosts.append(vip)
  
      kwargs = {'database': database,
                'username': database_user,
                'hostname': json.dumps(hosts)}
  
      if relation_prefix:
          for key in list(kwargs.keys()):
              kwargs["%s_%s" % (relation_prefix, key)] = kwargs[key]
              del kwargs[key]
  
      for rid in relation_ids('shared-db'):
          relation_set(relation_id=rid, **kwargs)
  
  
  def os_requires_version(ostack_release, pkg):
      """
      Decorator for hook to specify minimum supported release
      """
      def wrap(f):
          @wraps(f)
          def wrapped_f(*args):
              if os_release(pkg) < ostack_release:
                  raise Exception("This hook is not supported on releases"
                                  " before %s" % ostack_release)
              f(*args)
          return wrapped_f
      return wrap
  
  
  def os_workload_status(configs, required_interfaces, charm_func=None):
      """
      Decorator to set workload status based on complete contexts
      """
      def wrap(f):
          @wraps(f)
          def wrapped_f(*args, **kwargs):
              # Run the original function first
              f(*args, **kwargs)
              # Set workload status now that contexts have been
              # acted on
              set_os_workload_status(configs, required_interfaces, charm_func)
          return wrapped_f
      return wrap
  
  
  def set_os_workload_status(configs, required_interfaces, charm_func=None,
                             services=None, ports=None):
      """Set the state of the workload status for the charm.
  
      This calls _determine_os_workload_status() to get the new state, message
      and sets the status using status_set()
  
      @param configs: a templating.OSConfigRenderer() object
      @param required_interfaces: {generic: [specific, specific2, ...]}
      @param charm_func: a callable function that returns state, message. The
                         signature is charm_func(configs) -> (state, message)
      @param services: list of strings OR dictionary specifying services/ports
      @param ports: OPTIONAL list of port numbers.
      @returns state, message: the new workload status, user message
      """
      state, message = _determine_os_workload_status(
          configs, required_interfaces, charm_func, services, ports)
      status_set(state, message)
  
  
  def _determine_os_workload_status(
          configs, required_interfaces, charm_func=None,
          services=None, ports=None):
      """Determine the state of the workload status for the charm.
  
      This function returns the new workload status for the charm based
      on the state of the interfaces, the paused state and whether the
      services are actually running and any specified ports are open.
  
      This checks:
  
       1. if the unit should be paused, that it is actually paused.  If so the
          state is 'maintenance' + message, else 'broken'.
       2. that the interfaces/relations are complete.  If they are not then
          it sets the state to either 'broken' or 'waiting' and an appropriate
          message.
       3. If all the relation data is set, then it checks that the actual
          services really are running.  If not it sets the state to 'broken'.
  
      If everything is okay then the state returns 'active'.
  
      @param configs: a templating.OSConfigRenderer() object
      @param required_interfaces: {generic: [specific, specific2, ...]}
      @param charm_func: a callable function that returns state, message. The
                         signature is charm_func(configs) -> (state, message)
      @param services: list of strings OR dictionary specifying services/ports
      @param ports: OPTIONAL list of port numbers.
      @returns state, message: the new workload status, user message
      """
      state, message = _ows_check_if_paused(services, ports)
  
      if state is None:
          state, message = _ows_check_generic_interfaces(
              configs, required_interfaces)
  
      if state != 'maintenance' and charm_func:
          # _ows_check_charm_func() may modify the state, message
          state, message = _ows_check_charm_func(
              state, message, lambda: charm_func(configs))
  
      if state is None:
          state, message = _ows_check_services_running(services, ports)
  
      if state is None:
          state = 'active'
          message = "Unit is ready"
          juju_log(message, 'INFO')
  
      try:
          if config(POLICYD_CONFIG_NAME):
              message = "{} {}".format(policyd_status_message_prefix(), message)
      except Exception:
          pass
  
      return state, message
  
  
  def _ows_check_if_paused(services=None, ports=None):
      """Check if the unit is supposed to be paused, and if so check that the
      services/ports (if passed) are actually stopped/not being listened to.
  
      If the unit isn't supposed to be paused, just return None, None
  
      If the unit is performing a series upgrade, return a message indicating
      this.
  
      @param services: OPTIONAL services spec or list of service names.
      @param ports: OPTIONAL list of port numbers.
      @returns state, message or None, None
      """
      if is_unit_upgrading_set():
          state, message = check_actually_paused(services=services,
                                                 ports=ports)
          if state is None:
              # we're paused okay, so set maintenance and return
              state = "blocked"
              message = ("Ready for do-release-upgrade and reboot. "
                         "Set complete when finished.")
          return state, message
  
      if is_unit_paused_set():
          state, message = check_actually_paused(services=services,
                                                 ports=ports)
          if state is None:
              # we're paused okay, so set maintenance and return
              state = "maintenance"
              message = "Paused. Use 'resume' action to resume normal service."
          return state, message
      return None, None
  
  
  def _ows_check_generic_interfaces(configs, required_interfaces):
      """Check the complete contexts to determine the workload status.
  
       - Checks for missing or incomplete contexts
       - juju log details of missing required data.
       - determines the correct workload status
       - creates an appropriate message for status_set(...)
  
      if there are no problems then the function returns None, None
  
      @param configs: a templating.OSConfigRenderer() object
      @params required_interfaces: {generic_interface: [specific_interface], }
      @returns state, message or None, None
      """
      incomplete_rel_data = incomplete_relation_data(configs,
                                                     required_interfaces)
      state = None
      message = None
      missing_relations = set()
      incomplete_relations = set()
  
      for generic_interface, relations_states in incomplete_rel_data.items():
          related_interface = None
          missing_data = {}
          # Related or not?
          for interface, relation_state in relations_states.items():
              if relation_state.get('related'):
                  related_interface = interface
                  missing_data = relation_state.get('missing_data')
                  break
          # No relation ID for the generic_interface?
          if not related_interface:
              juju_log("{} relation is missing and must be related for "
                       "functionality. ".format(generic_interface), 'WARN')
              state = 'blocked'
              missing_relations.add(generic_interface)
          else:
              # Relation ID eists but no related unit
              if not missing_data:
                  # Edge case - relation ID exists but departings
                  _hook_name = hook_name()
                  if (('departed' in _hook_name or 'broken' in _hook_name) and
                          related_interface in _hook_name):
                      state = 'blocked'
                      missing_relations.add(generic_interface)
                      juju_log("{} relation's interface, {}, "
                               "relationship is departed or broken "
                               "and is required for functionality."
                               "".format(generic_interface, related_interface),
                               "WARN")
                  # Normal case relation ID exists but no related unit
                  # (joining)
                  else:
                      juju_log("{} relations's interface, {}, is related but has"
                               " no units in the relation."
                               "".format(generic_interface, related_interface),
                               "INFO")
              # Related unit exists and data missing on the relation
              else:
                  juju_log("{} relation's interface, {}, is related awaiting "
                           "the following data from the relationship: {}. "
                           "".format(generic_interface, related_interface,
                                     ", ".join(missing_data)), "INFO")
              if state != 'blocked':
                  state = 'waiting'
              if generic_interface not in missing_relations:
                  incomplete_relations.add(generic_interface)
  
      if missing_relations:
          message = "Missing relations: {}".format(", ".join(missing_relations))
          if incomplete_relations:
              message += "; incomplete relations: {}" \
                         "".format(", ".join(incomplete_relations))
          state = 'blocked'
      elif incomplete_relations:
          message = "Incomplete relations: {}" \
                    "".format(", ".join(incomplete_relations))
          state = 'waiting'
  
      return state, message
  
  
  def _ows_check_charm_func(state, message, charm_func_with_configs):
      """Run a custom check function for the charm to see if it wants to
      change the state.  This is only run if not in 'maintenance' and
      tests to see if the new state is more important that the previous
      one determined by the interfaces/relations check.
  
      @param state: the previously determined state so far.
      @param message: the user orientated message so far.
      @param charm_func: a callable function that returns state, message
      @returns state, message strings.
      """
      if charm_func_with_configs:
          charm_state, charm_message = charm_func_with_configs()
          if (charm_state != 'active' and
                  charm_state != 'unknown' and
                  charm_state is not None):
              state = workload_state_compare(state, charm_state)
              if message:
                  charm_message = charm_message.replace("Incomplete relations: ",
                                                        "")
                  message = "{}, {}".format(message, charm_message)
              else:
                  message = charm_message
      return state, message
  
  
  def _ows_check_services_running(services, ports):
      """Check that the services that should be running are actually running
      and that any ports specified are being listened to.
  
      @param services: list of strings OR dictionary specifying services/ports
      @param ports: list of ports
      @returns state, message: strings or None, None
      """
      messages = []
      state = None
      if services is not None:
          services = _extract_services_list_helper(services)
          services_running, running = _check_running_services(services)
          if not all(running):
              messages.append(
                  "Services not running that should be: {}"
                  .format(", ".join(_filter_tuples(services_running, False))))
              state = 'blocked'
          # also verify that the ports that should be open are open
          # NB, that ServiceManager objects only OPTIONALLY have ports
          map_not_open, ports_open = (
              _check_listening_on_services_ports(services))
          if not all(ports_open):
              # find which service has missing ports. They are in service
              # order which makes it a bit easier.
              message_parts = {service: ", ".join([str(v) for v in open_ports])
                               for service, open_ports in map_not_open.items()}
              message = ", ".join(
                  ["{}: [{}]".format(s, sp) for s, sp in message_parts.items()])
              messages.append(
                  "Services with ports not open that should be: {}"
                  .format(message))
              state = 'blocked'
  
      if ports is not None:
          # and we can also check ports which we don't know the service for
          ports_open, ports_open_bools = _check_listening_on_ports_list(ports)
          if not all(ports_open_bools):
              messages.append(
                  "Ports which should be open, but are not: {}"
                  .format(", ".join([str(p) for p, v in ports_open
                                     if not v])))
              state = 'blocked'
  
      if state is not None:
          message = "; ".join(messages)
          return state, message
  
      return None, None
  
  
  def _extract_services_list_helper(services):
      """Extract a OrderedDict of {service: [ports]} of the supplied services
      for use by the other functions.
  
      The services object can either be:
        - None : no services were passed (an empty dict is returned)
        - a list of strings
        - A dictionary (optionally OrderedDict) {service_name: {'service': ..}}
        - An array of [{'service': service_name, ...}, ...]
  
      @param services: see above
      @returns OrderedDict(service: [ports], ...)
      """
      if services is None:
          return {}
      if isinstance(services, dict):
          services = services.values()
      # either extract the list of services from the dictionary, or if
      # it is a simple string, use that. i.e. works with mixed lists.
      _s = OrderedDict()
      for s in services:
          if isinstance(s, dict) and 'service' in s:
              _s[s['service']] = s.get('ports', [])
          if isinstance(s, str):
              _s[s] = []
      return _s
  
  
  def _check_running_services(services):
      """Check that the services dict provided is actually running and provide
      a list of (service, boolean) tuples for each service.
  
      Returns both a zipped list of (service, boolean) and a list of booleans
      in the same order as the services.
  
      @param services: OrderedDict of strings: [ports], one for each service to
                       check.
      @returns [(service, boolean), ...], : results for checks
               [boolean]                  : just the result of the service checks
      """
      services_running = [service_running(s) for s in services]
      return list(zip(services, services_running)), services_running
  
  
  def _check_listening_on_services_ports(services, test=False):
      """Check that the unit is actually listening (has the port open) on the
      ports that the service specifies are open. If test is True then the
      function returns the services with ports that are open rather than
      closed.
  
      Returns an OrderedDict of service: ports and a list of booleans
  
      @param services: OrderedDict(service: [port, ...], ...)
      @param test: default=False, if False, test for closed, otherwise open.
      @returns OrderedDict(service: [port-not-open, ...]...), [boolean]
      """
      test = not(not(test))  # ensure test is True or False
      all_ports = list(itertools.chain(*services.values()))
      ports_states = [port_has_listener('0.0.0.0', p) for p in all_ports]
      map_ports = OrderedDict()
      matched_ports = [p for p, opened in zip(all_ports, ports_states)
                       if opened == test]  # essentially opened xor test
      for service, ports in services.items():
          set_ports = set(ports).intersection(matched_ports)
          if set_ports:
              map_ports[service] = set_ports
      return map_ports, ports_states
  
  
  def _check_listening_on_ports_list(ports):
      """Check that the ports list given are being listened to
  
      Returns a list of ports being listened to and a list of the
      booleans.
  
      @param ports: LIST or port numbers.
      @returns [(port_num, boolean), ...], [boolean]
      """
      ports_open = [port_has_listener('0.0.0.0', p) for p in ports]
      return zip(ports, ports_open), ports_open
  
  
  def _filter_tuples(services_states, state):
      """Return a simple list from a list of tuples according to the condition
  
      @param services_states: LIST of (string, boolean): service and running
             state.
      @param state: Boolean to match the tuple against.
      @returns [LIST of strings] that matched the tuple RHS.
      """
      return [s for s, b in services_states if b == state]
  
  
  def workload_state_compare(current_workload_state, workload_state):
      """ Return highest priority of two states"""
      hierarchy = {'unknown': -1,
                   'active': 0,
                   'maintenance': 1,
                   'waiting': 2,
                   'blocked': 3,
                   }
  
      if hierarchy.get(workload_state) is None:
          workload_state = 'unknown'
      if hierarchy.get(current_workload_state) is None:
          current_workload_state = 'unknown'
  
      # Set workload_state based on hierarchy of statuses
      if hierarchy.get(current_workload_state) > hierarchy.get(workload_state):
          return current_workload_state
      else:
          return workload_state
  
  
  def incomplete_relation_data(configs, required_interfaces):
      """Check complete contexts against required_interfaces
      Return dictionary of incomplete relation data.
  
      configs is an OSConfigRenderer object with configs registered
  
      required_interfaces is a dictionary of required general interfaces
      with dictionary values of possible specific interfaces.
      Example:
      required_interfaces = {'database': ['shared-db', 'pgsql-db']}
  
      The interface is said to be satisfied if anyone of the interfaces in the
      list has a complete context.
  
      Return dictionary of incomplete or missing required contexts with relation
      status of interfaces and any missing data points. Example:
          {'message':
               {'amqp': {'missing_data': ['rabbitmq_password'], 'related': True},
                'zeromq-configuration': {'related': False}},
           'identity':
               {'identity-service': {'related': False}},
           'database':
               {'pgsql-db': {'related': False},
                'shared-db': {'related': True}}}
      """
      complete_ctxts = configs.complete_contexts()
      incomplete_relations = [
          svc_type
          for svc_type, interfaces in required_interfaces.items()
          if not set(interfaces).intersection(complete_ctxts)]
      return {
          i: configs.get_incomplete_context_data(required_interfaces[i])
          for i in incomplete_relations}
  
  
  def do_action_openstack_upgrade(package, upgrade_callback, configs):
      """Perform action-managed OpenStack upgrade.
  
      Upgrades packages to the configured openstack-origin version and sets
      the corresponding action status as a result.
  
      If the charm was installed from source we cannot upgrade it.
      For backwards compatibility a config flag (action-managed-upgrade) must
      be set for this code to run, otherwise a full service level upgrade will
      fire on config-changed.
  
      @param package: package name for determining if upgrade available
      @param upgrade_callback: function callback to charm's upgrade function
      @param configs: templating object derived from OSConfigRenderer class
  
      @return: True if upgrade successful; False if upgrade failed or skipped
      """
      ret = False
  
      if openstack_upgrade_available(package):
          if config('action-managed-upgrade'):
              juju_log('Upgrading OpenStack release')
  
              try:
                  upgrade_callback(configs=configs)
                  action_set({'outcome': 'success, upgrade completed.'})
                  ret = True
              except Exception:
                  action_set({'outcome': 'upgrade failed, see traceback.'})
                  action_set({'traceback': traceback.format_exc()})
                  action_fail('do_openstack_upgrade resulted in an '
                              'unexpected error')
          else:
              action_set({'outcome': 'action-managed-upgrade config is '
                                     'False, skipped upgrade.'})
      else:
          action_set({'outcome': 'no upgrade available.'})
  
      return ret
  
  
  def remote_restart(rel_name, remote_service=None):
      trigger = {
          'restart-trigger': str(uuid.uuid4()),
      }
      if remote_service:
          trigger['remote-service'] = remote_service
      for rid in relation_ids(rel_name):
          # This subordinate can be related to two seperate services using
          # different subordinate relations so only issue the restart if
          # the principle is conencted down the relation we think it is
          if related_units(relid=rid):
              relation_set(relation_id=rid,
                           relation_settings=trigger,
                           )
  
  
  def check_actually_paused(services=None, ports=None):
      """Check that services listed in the services object and ports
      are actually closed (not listened to), to verify that the unit is
      properly paused.
  
      @param services: See _extract_services_list_helper
      @returns status, : string for status (None if okay)
               message : string for problem for status_set
      """
      state = None
      message = None
      messages = []
      if services is not None:
          services = _extract_services_list_helper(services)
          services_running, services_states = _check_running_services(services)
          if any(services_states):
              # there shouldn't be any running so this is a problem
              messages.append("these services running: {}"
                              .format(", ".join(
                                  _filter_tuples(services_running, True))))
              state = "blocked"
          ports_open, ports_open_bools = (
              _check_listening_on_services_ports(services, True))
          if any(ports_open_bools):
              message_parts = {service: ", ".join([str(v) for v in open_ports])
                               for service, open_ports in ports_open.items()}
              message = ", ".join(
                  ["{}: [{}]".format(s, sp) for s, sp in message_parts.items()])
              messages.append(
                  "these service:ports are open: {}".format(message))
              state = 'blocked'
      if ports is not None:
          ports_open, bools = _check_listening_on_ports_list(ports)
          if any(bools):
              messages.append(
                  "these ports which should be closed, but are open: {}"
                  .format(", ".join([str(p) for p, v in ports_open if v])))
              state = 'blocked'
      if messages:
          message = ("Services should be paused but {}"
                     .format(", ".join(messages)))
      return state, message
  
  
  def set_unit_paused():
      """Set the unit to a paused state in the local kv() store.
      This does NOT actually pause the unit
      """
      with unitdata.HookData()() as t:
          kv = t[0]
          kv.set('unit-paused', True)
  
  
  def clear_unit_paused():
      """Clear the unit from a paused state in the local kv() store
      This does NOT actually restart any services - it only clears the
      local state.
      """
      with unitdata.HookData()() as t:
          kv = t[0]
          kv.set('unit-paused', False)
  
  
  def is_unit_paused_set():
      """Return the state of the kv().get('unit-paused').
      This does NOT verify that the unit really is paused.
  
      To help with units that don't have HookData() (testing)
      if it excepts, return False
      """
      try:
          with unitdata.HookData()() as t:
              kv = t[0]
              # transform something truth-y into a Boolean.
              return not(not(kv.get('unit-paused')))
      except Exception:
          return False
  
  
  def manage_payload_services(action, services=None, charm_func=None):
      """Run an action against all services.
  
      An optional charm_func() can be called. It should raise an Exception to
      indicate that the function failed. If it was succesfull it should return
      None or an optional message.
  
      The signature for charm_func is:
      charm_func() -> message: str
  
      charm_func() is executed after any services are stopped, if supplied.
  
      The services object can either be:
        - None : no services were passed (an empty dict is returned)
        - a list of strings
        - A dictionary (optionally OrderedDict) {service_name: {'service': ..}}
        - An array of [{'service': service_name, ...}, ...]
  
      :param action: Action to run: pause, resume, start or stop.
      :type action: str
      :param services: See above
      :type services: See above
      :param charm_func: function to run for custom charm pausing.
      :type charm_func: f()
      :returns: Status boolean and list of messages
      :rtype: (bool, [])
      :raises: RuntimeError
      """
      actions = {
          'pause': service_pause,
          'resume': service_resume,
          'start': service_start,
          'stop': service_stop}
      action = action.lower()
      if action not in actions.keys():
          raise RuntimeError(
              "action: {} must be one of: {}".format(action,
                                                     ', '.join(actions.keys())))
      services = _extract_services_list_helper(services)
      messages = []
      success = True
      if services:
          for service in services.keys():
              rc = actions[action](service)
              if not rc:
                  success = False
                  messages.append("{} didn't {} cleanly.".format(service,
                                                                 action))
      if charm_func:
          try:
              message = charm_func()
              if message:
                  messages.append(message)
          except Exception as e:
              success = False
              messages.append(str(e))
      return success, messages
  
  
  def pause_unit(assess_status_func, services=None, ports=None,
                 charm_func=None):
      """Pause a unit by stopping the services and setting 'unit-paused'
      in the local kv() store.
  
      Also checks that the services have stopped and ports are no longer
      being listened to.
  
      An optional charm_func() can be called that can either raise an
      Exception or return non None, None to indicate that the unit
      didn't pause cleanly.
  
      The signature for charm_func is:
      charm_func() -> message: string
  
      charm_func() is executed after any services are stopped, if supplied.
  
      The services object can either be:
        - None : no services were passed (an empty dict is returned)
        - a list of strings
        - A dictionary (optionally OrderedDict) {service_name: {'service': ..}}
        - An array of [{'service': service_name, ...}, ...]
  
      @param assess_status_func: (f() -> message: string | None) or None
      @param services: OPTIONAL see above
      @param ports: OPTIONAL list of port
      @param charm_func: function to run for custom charm pausing.
      @returns None
      @raises Exception(message) on an error for action_fail().
      """
      _, messages = manage_payload_services(
          'pause',
          services=services,
          charm_func=charm_func)
      set_unit_paused()
      if assess_status_func:
          message = assess_status_func()
          if message:
              messages.append(message)
      if messages and not is_unit_upgrading_set():
          raise Exception("Couldn't pause: {}".format("; ".join(messages)))
  
  
  def resume_unit(assess_status_func, services=None, ports=None,
                  charm_func=None):
      """Resume a unit by starting the services and clearning 'unit-paused'
      in the local kv() store.
  
      Also checks that the services have started and ports are being listened to.
  
      An optional charm_func() can be called that can either raise an
      Exception or return non None to indicate that the unit
      didn't resume cleanly.
  
      The signature for charm_func is:
      charm_func() -> message: string
  
      charm_func() is executed after any services are started, if supplied.
  
      The services object can either be:
        - None : no services were passed (an empty dict is returned)
        - a list of strings
        - A dictionary (optionally OrderedDict) {service_name: {'service': ..}}
        - An array of [{'service': service_name, ...}, ...]
  
      @param assess_status_func: (f() -> message: string | None) or None
      @param services: OPTIONAL see above
      @param ports: OPTIONAL list of port
      @param charm_func: function to run for custom charm resuming.
      @returns None
      @raises Exception(message) on an error for action_fail().
      """
      _, messages = manage_payload_services(
          'resume',
          services=services,
          charm_func=charm_func)
      clear_unit_paused()
      if assess_status_func:
          message = assess_status_func()
          if message:
              messages.append(message)
      if messages:
          raise Exception("Couldn't resume: {}".format("; ".join(messages)))
  
  
  def make_assess_status_func(*args, **kwargs):
      """Creates an assess_status_func() suitable for handing to pause_unit()
      and resume_unit().
  
      This uses the _determine_os_workload_status(...) function to determine
      what the workload_status should be for the unit.  If the unit is
      not in maintenance or active states, then the message is returned to
      the caller.  This is so an action that doesn't result in either a
      complete pause or complete resume can signal failure with an action_fail()
      """
      def _assess_status_func():
          state, message = _determine_os_workload_status(*args, **kwargs)
          status_set(state, message)
          if state not in ['maintenance', 'active']:
              return message
          return None
  
      return _assess_status_func
  
  
  def pausable_restart_on_change(restart_map, stopstart=False,
                                 restart_functions=None):
      """A restart_on_change decorator that checks to see if the unit is
      paused. If it is paused then the decorated function doesn't fire.
  
      This is provided as a helper, as the @restart_on_change(...) decorator
      is in core.host, yet the openstack specific helpers are in this file
      (contrib.openstack.utils).  Thus, this needs to be an optional feature
      for openstack charms (or charms that wish to use the openstack
      pause/resume type features).
  
      It is used as follows:
  
          from contrib.openstack.utils import (
              pausable_restart_on_change as restart_on_change)
  
          @restart_on_change(restart_map, stopstart=<boolean>)
          def some_hook(...):
              pass
  
      see core.utils.restart_on_change() for more details.
  
      Note restart_map can be a callable, in which case, restart_map is only
      evaluated at runtime.  This means that it is lazy and the underlying
      function won't be called if the decorated function is never called.  Note,
      retains backwards compatibility for passing a non-callable dictionary.
  
      @param f: the function to decorate
      @param restart_map: (optionally callable, which then returns the
          restart_map) the restart map {conf_file: [services]}
      @param stopstart: DEFAULT false; whether to stop, start or just restart
      @returns decorator to use a restart_on_change with pausability
      """
      def wrap(f):
          # py27 compatible nonlocal variable.  When py3 only, replace with
          # nonlocal keyword
          __restart_map_cache = {'cache': None}
  
          @functools.wraps(f)
          def wrapped_f(*args, **kwargs):
              if is_unit_paused_set():
                  return f(*args, **kwargs)
              if __restart_map_cache['cache'] is None:
                  __restart_map_cache['cache'] = restart_map() \
                      if callable(restart_map) else restart_map
              # otherwise, normal restart_on_change functionality
              return restart_on_change_helper(
                  (lambda: f(*args, **kwargs)), __restart_map_cache['cache'],
                  stopstart, restart_functions)
          return wrapped_f
      return wrap
  
  
  def ordered(orderme):
      """Converts the provided dictionary into a collections.OrderedDict.
  
      The items in the returned OrderedDict will be inserted based on the
      natural sort order of the keys. Nested dictionaries will also be sorted
      in order to ensure fully predictable ordering.
  
      :param orderme: the dict to order
      :return: collections.OrderedDict
      :raises: ValueError: if `orderme` isn't a dict instance.
      """
      if not isinstance(orderme, dict):
          raise ValueError('argument must be a dict type')
  
      result = OrderedDict()
      for k, v in sorted(six.iteritems(orderme), key=lambda x: x[0]):
          if isinstance(v, dict):
              result[k] = ordered(v)
          else:
              result[k] = v
  
      return result
  
  
  def config_flags_parser(config_flags):
      """Parses config flags string into dict.
  
      This parsing method supports a few different formats for the config
      flag values to be parsed:
  
        1. A string in the simple format of key=value pairs, with the possibility
           of specifying multiple key value pairs within the same string. For
           example, a string in the format of 'key1=value1, key2=value2' will
           return a dict of:
  
               {'key1': 'value1', 'key2': 'value2'}.
  
        2. A string in the above format, but supporting a comma-delimited list
           of values for the same key. For example, a string in the format of
           'key1=value1, key2=value3,value4,value5' will return a dict of:
  
               {'key1': 'value1', 'key2': 'value2,value3,value4'}
  
        3. A string containing a colon character (:) prior to an equal
           character (=) will be treated as yaml and parsed as such. This can be
           used to specify more complex key value pairs. For example,
           a string in the format of 'key1: subkey1=value1, subkey2=value2' will
           return a dict of:
  
               {'key1', 'subkey1=value1, subkey2=value2'}
  
      The provided config_flags string may be a list of comma-separated values
      which themselves may be comma-separated list of values.
      """
      # If we find a colon before an equals sign then treat it as yaml.
      # Note: limit it to finding the colon first since this indicates assignment
      # for inline yaml.
      colon = config_flags.find(':')
      equals = config_flags.find('=')
      if colon > 0:
          if colon < equals or equals < 0:
              return ordered(yaml.safe_load(config_flags))
  
      if config_flags.find('==') >= 0:
          juju_log("config_flags is not in expected format (key=value)",
                   level=ERROR)
          raise OSContextError
  
      # strip the following from each value.
      post_strippers = ' ,'
      # we strip any leading/trailing '=' or ' ' from the string then
      # split on '='.
      split = config_flags.strip(' =').split('=')
      limit = len(split)
      flags = OrderedDict()
      for i in range(0, limit - 1):
          current = split[i]
          next = split[i + 1]
          vindex = next.rfind(',')
          if (i == limit - 2) or (vindex < 0):
              value = next
          else:
              value = next[:vindex]
  
          if i == 0:
              key = current
          else:
              # if this not the first entry, expect an embedded key.
              index = current.rfind(',')
              if index < 0:
                  juju_log("Invalid config value(s) at index %s" % (i),
                           level=ERROR)
                  raise OSContextError
              key = current[index + 1:]
  
          # Add to collection.
          flags[key.strip(post_strippers)] = value.rstrip(post_strippers)
  
      return flags
  
  
  def os_application_version_set(package):
      '''Set version of application for Juju 2.0 and later'''
      application_version = get_upstream_version(package)
      # NOTE(jamespage) if not able to figure out package version, fallback to
      #                 openstack codename version detection.
      if not application_version:
          application_version_set(os_release(package))
      else:
          application_version_set(application_version)
  
  
  def enable_memcache(source=None, release=None, package=None):
      """Determine if memcache should be enabled on the local unit
  
      @param release: release of OpenStack currently deployed
      @param package: package to derive OpenStack version deployed
      @returns boolean Whether memcache should be enabled
      """
      _release = None
      if release:
          _release = release
      else:
          _release = os_release(package)
      if not _release:
          _release = get_os_codename_install_source(source)
  
      return CompareOpenStackReleases(_release) >= 'mitaka'
  
  
  def token_cache_pkgs(source=None, release=None):
      """Determine additional packages needed for token caching
  
      @param source: source string for charm
      @param release: release of OpenStack currently deployed
      @returns List of package to enable token caching
      """
      packages = []
      if enable_memcache(source=source, release=release):
          packages.extend(['memcached', 'python-memcache'])
      return packages
  
  
  def update_json_file(filename, items):
      """Updates the json `filename` with a given dict.
      :param filename: path to json file (e.g. /etc/glance/policy.json)
      :param items: dict of items to update
      """
      if not items:
          return
  
      with open(filename) as fd:
          policy = json.load(fd)
  
      # Compare before and after and if nothing has changed don't write the file
      # since that could cause unnecessary service restarts.
      before = json.dumps(policy, indent=4, sort_keys=True)
      policy.update(items)
      after = json.dumps(policy, indent=4, sort_keys=True)
      if before == after:
          return
  
      with open(filename, "w") as fd:
          fd.write(after)
  
  
  @cached
  def snap_install_requested():
      """ Determine if installing from snaps
  
      If openstack-origin is of the form snap:track/channel[/branch]
      and channel is in SNAPS_CHANNELS return True.
      """
      origin = config('openstack-origin') or ""
      if not origin.startswith('snap:'):
          return False
  
      _src = origin[5:]
      if '/' in _src:
          channel = _src.split('/')[1]
      else:
          # Handle snap:track with no channel
          channel = 'stable'
      return valid_snap_channel(channel)
  
  
  def get_snaps_install_info_from_origin(snaps, src, mode='classic'):
      """Generate a dictionary of snap install information from origin
  
      @param snaps: List of snaps
      @param src: String of openstack-origin or source of the form
          snap:track/channel
      @param mode: String classic, devmode or jailmode
      @returns: Dictionary of snaps with channels and modes
      """
  
      if not src.startswith('snap:'):
          juju_log("Snap source is not a snap origin", 'WARN')
          return {}
  
      _src = src[5:]
      channel = '--channel={}'.format(_src)
  
      return {snap: {'channel': channel, 'mode': mode}
              for snap in snaps}
  
  
  def install_os_snaps(snaps, refresh=False):
      """Install OpenStack snaps from channel and with mode
  
      @param snaps: Dictionary of snaps with channels and modes of the form:
          {'snap_name': {'channel': 'snap_channel',
                         'mode': 'snap_mode'}}
          Where channel is a snapstore channel and mode is --classic, --devmode
          or --jailmode.
      @param post_snap_install: Callback function to run after snaps have been
      installed
      """
  
      def _ensure_flag(flag):
          if flag.startswith('--'):
              return flag
          return '--{}'.format(flag)
  
      if refresh:
          for snap in snaps.keys():
              snap_refresh(snap,
                           _ensure_flag(snaps[snap]['channel']),
                           _ensure_flag(snaps[snap]['mode']))
      else:
          for snap in snaps.keys():
              snap_install(snap,
                           _ensure_flag(snaps[snap]['channel']),
                           _ensure_flag(snaps[snap]['mode']))
  
  
  def set_unit_upgrading():
      """Set the unit to a upgrading state in the local kv() store.
      """
      with unitdata.HookData()() as t:
          kv = t[0]
          kv.set('unit-upgrading', True)
  
  
  def clear_unit_upgrading():
      """Clear the unit from a upgrading state in the local kv() store
      """
      with unitdata.HookData()() as t:
          kv = t[0]
          kv.set('unit-upgrading', False)
  
  
  def is_unit_upgrading_set():
      """Return the state of the kv().get('unit-upgrading').
  
      To help with units that don't have HookData() (testing)
      if it excepts, return False
      """
      try:
          with unitdata.HookData()() as t:
              kv = t[0]
              # transform something truth-y into a Boolean.
              return not(not(kv.get('unit-upgrading')))
      except Exception:
          return False
  
  
  def series_upgrade_prepare(pause_unit_helper=None, configs=None):
      """ Run common series upgrade prepare tasks.
  
      :param pause_unit_helper: function: Function to pause unit
      :param configs: OSConfigRenderer object: Configurations
      :returns None:
      """
      set_unit_upgrading()
      if pause_unit_helper and configs:
          if not is_unit_paused_set():
              pause_unit_helper(configs)
  
  
  def series_upgrade_complete(resume_unit_helper=None, configs=None):
      """ Run common series upgrade complete tasks.
  
      :param resume_unit_helper: function: Function to resume unit
      :param configs: OSConfigRenderer object: Configurations
      :returns None:
      """
      clear_unit_paused()
      clear_unit_upgrading()
      if configs:
          configs.write_all()
          if resume_unit_helper:
              resume_unit_helper(configs)
  
  
  def is_db_initialised():
      """Check leader storage to see if database has been initialised.
  
      :returns: Whether DB has been initialised
      :rtype: bool
      """
      db_initialised = None
      if leader_get('db-initialised') is None:
          juju_log(
              'db-initialised key missing, assuming db is not initialised',
              'DEBUG')
          db_initialised = False
      else:
          db_initialised = bool_from_string(leader_get('db-initialised'))
      juju_log('Database initialised: {}'.format(db_initialised), 'DEBUG')
      return db_initialised
  
  
  def set_db_initialised():
      """Add flag to leader storage to indicate database has been initialised.
      """
      juju_log('Setting db-initialised to True', 'DEBUG')
      leader_set({'db-initialised': True})
  