diff --git a/hooks/charmhelpers/contrib/hahelpers/cluster.py b/hooks/charmhelpers/contrib/hahelpers/cluster.py
index 9333efc3..5790b46f 100644
--- a/hooks/charmhelpers/contrib/hahelpers/cluster.py
+++ b/hooks/charmhelpers/contrib/hahelpers/cluster.py
@@ -44,6 +44,7 @@ from charmhelpers.core.hookenv import (
     ERROR,
     WARNING,
     unit_get,
+    is_leader as juju_is_leader
 )
 from charmhelpers.core.decorators import (
     retry_on_exception,
@@ -52,6 +53,8 @@ from charmhelpers.core.strutils import (
     bool_from_string,
 )
 
+DC_RESOURCE_NAME = 'DC'
+
 
 class HAIncompleteConfig(Exception):
     pass
@@ -66,12 +69,21 @@ def is_elected_leader(resource):
     Returns True if the charm executing this is the elected cluster leader.
 
     It relies on two mechanisms to determine leadership:
-        1. If the charm is part of a corosync cluster, call corosync to
+        1. If juju is sufficiently new and leadership election is supported,
+        the is_leader command will be used.
+        2. If the charm is part of a corosync cluster, call corosync to
         determine leadership.
-        2. If the charm is not part of a corosync cluster, the leader is
+        3. If the charm is not part of a corosync cluster, the leader is
         determined as being "the alive unit with the lowest unit numer". In
         other words, the oldest surviving unit.
     """
+    try:
+        return juju_is_leader()
+    except NotImplementedError:
+        log('Juju leadership election feature not enabled'
+            ', using fallback support',
+            level=WARNING)
+
     if is_clustered():
         if not is_crm_leader(resource):
             log('Deferring action to CRM leader.', level=INFO)
@@ -95,6 +107,27 @@ def is_clustered():
     return False
 
 
+def is_crm_dc():
+    """
+    Determine leadership by querying the pacemaker Designated Controller
+    """
+    cmd = ['crm', 'status']
+    try:
+        status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
+        if not isinstance(status, six.text_type):
+            status = six.text_type(status, "utf-8")
+    except subprocess.CalledProcessError:
+        return False
+    current_dc = ''
+    for line in status.split('\n'):
+        if line.startswith('Current DC'):
+            # Current DC: juju-lytrusty-machine-2 (168108163) - partition with quorum
+            current_dc = line.split(':')[1].split()[0]
+    if current_dc == get_unit_hostname():
+        return True
+    return False
+
+
 @retry_on_exception(5, base_delay=2, exc_type=CRMResourceNotFound)
 def is_crm_leader(resource, retry=False):
     """
@@ -104,6 +137,8 @@ def is_crm_leader(resource, retry=False):
     We allow this operation to be retried to avoid the possibility of getting a
     false negative. See LP #1396246 for more info.
     """
+    if resource == DC_RESOURCE_NAME:
+        return is_crm_dc()
     cmd = ['crm', 'resource', 'show', resource]
     try:
         status = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
diff --git a/hooks/charmhelpers/contrib/openstack/neutron.py b/hooks/charmhelpers/contrib/openstack/neutron.py
index 02c92e9c..b3aa3d4c 100644
--- a/hooks/charmhelpers/contrib/openstack/neutron.py
+++ b/hooks/charmhelpers/contrib/openstack/neutron.py
@@ -256,11 +256,14 @@ def network_manager():
 def parse_mappings(mappings):
     parsed = {}
     if mappings:
-        mappings = mappings.split(' ')
+        mappings = mappings.split()
         for m in mappings:
             p = m.partition(':')
-            if p[1] == ':':
-                parsed[p[0].strip()] = p[2].strip()
+            key = p[0].strip()
+            if p[1]:
+                parsed[key] = p[2].strip()
+            else:
+                parsed[key] = ''
 
     return parsed
 
@@ -283,13 +286,13 @@ def parse_data_port_mappings(mappings, default_bridge='br-data'):
     Returns dict of the form {bridge:port}.
     """
     _mappings = parse_mappings(mappings)
-    if not _mappings:
+    if not _mappings or list(_mappings.values()) == ['']:
         if not mappings:
             return {}
 
         # For backwards-compatibility we need to support port-only provided in
         # config.
-        _mappings = {default_bridge: mappings.split(' ')[0]}
+        _mappings = {default_bridge: mappings.split()[0]}
 
     bridges = _mappings.keys()
     ports = _mappings.values()
@@ -309,6 +312,8 @@ def parse_vlan_range_mappings(mappings):
 
     Mappings must be a space-delimited list of provider:start:end mappings.
 
+    The start:end range is optional and may be omitted.
+
     Returns dict of the form {provider: (start, end)}.
     """
     _mappings = parse_mappings(mappings)
diff --git a/hooks/charmhelpers/core/hookenv.py b/hooks/charmhelpers/core/hookenv.py
index 86f805f1..117429fd 100644
--- a/hooks/charmhelpers/core/hookenv.py
+++ b/hooks/charmhelpers/core/hookenv.py
@@ -21,12 +21,14 @@
 #  Charm Helpers Developers <juju@lists.ubuntu.com>
 
 from __future__ import print_function
+from functools import wraps
 import os
 import json
 import yaml
 import subprocess
 import sys
 import errno
+import tempfile
 from subprocess import CalledProcessError
 
 import six
@@ -58,15 +60,17 @@ def cached(func):
 
     will cache the result of unit_get + 'test' for future calls.
     """
+    @wraps(func)
     def wrapper(*args, **kwargs):
         global cache
         key = str((func, args, kwargs))
         try:
             return cache[key]
         except KeyError:
-            res = func(*args, **kwargs)
-            cache[key] = res
-            return res
+            pass  # Drop out of the exception handler scope.
+        res = func(*args, **kwargs)
+        cache[key] = res
+        return res
     return wrapper
 
 
@@ -178,7 +182,7 @@ def local_unit():
 
 def remote_unit():
     """The remote unit for the current relation hook"""
-    return os.environ['JUJU_REMOTE_UNIT']
+    return os.environ.get('JUJU_REMOTE_UNIT', None)
 
 
 def service_name():
@@ -250,6 +254,12 @@ class Config(dict):
         except KeyError:
             return (self._prev_dict or {})[key]
 
+    def get(self, key, default=None):
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
     def keys(self):
         prev_keys = []
         if self._prev_dict is not None:
@@ -353,18 +363,49 @@ def relation_set(relation_id=None, relation_settings=None, **kwargs):
     """Set relation information for the current unit"""
     relation_settings = relation_settings if relation_settings else {}
     relation_cmd_line = ['relation-set']
+    accepts_file = "--file" in subprocess.check_output(
+        relation_cmd_line + ["--help"], universal_newlines=True)
     if relation_id is not None:
         relation_cmd_line.extend(('-r', relation_id))
-    for k, v in (list(relation_settings.items()) + list(kwargs.items())):
-        if v is None:
-            relation_cmd_line.append('{}='.format(k))
-        else:
-            relation_cmd_line.append('{}={}'.format(k, v))
-    subprocess.check_call(relation_cmd_line)
+    settings = relation_settings.copy()
+    settings.update(kwargs)
+    for key, value in settings.items():
+        # Force value to be a string: it always should, but some call
+        # sites pass in things like dicts or numbers.
+        if value is not None:
+            settings[key] = "{}".format(value)
+    if accepts_file:
+        # --file was introduced in Juju 1.23.2. Use it by default if
+        # available, since otherwise we'll break if the relation data is
+        # too big. Ideally we should tell relation-set to read the data from
+        # stdin, but that feature is broken in 1.23.2: Bug #1454678.
+        with tempfile.NamedTemporaryFile(delete=False) as settings_file:
+            settings_file.write(yaml.safe_dump(settings).encode("utf-8"))
+        subprocess.check_call(
+            relation_cmd_line + ["--file", settings_file.name])
+        os.remove(settings_file.name)
+    else:
+        for key, value in settings.items():
+            if value is None:
+                relation_cmd_line.append('{}='.format(key))
+            else:
+                relation_cmd_line.append('{}={}'.format(key, value))
+        subprocess.check_call(relation_cmd_line)
     # Flush cache of any relation-gets for local unit
     flush(local_unit())
 
 
+def relation_clear(r_id=None):
+    ''' Clears any relation data already set on relation r_id '''
+    settings = relation_get(rid=r_id,
+                            unit=local_unit())
+    for setting in settings:
+        if setting not in ['public-address', 'private-address']:
+            settings[setting] = None
+    relation_set(relation_id=r_id,
+                 **settings)
+
+
 @cached
 def relation_ids(reltype=None):
     """A list of relation_ids"""
@@ -509,6 +550,11 @@ def unit_get(attribute):
         return None
 
 
+def unit_public_ip():
+    """Get this unit's public IP address"""
+    return unit_get('public-address')
+
+
 def unit_private_ip():
     """Get this unit's private IP address"""
     return unit_get('private-address')
@@ -605,3 +651,94 @@ def action_fail(message):
 
     The results set by action_set are preserved."""
     subprocess.check_call(['action-fail', message])
+
+
+def status_set(workload_state, message):
+    """Set the workload state with a message
+
+    Use status-set to set the workload state with a message which is visible
+    to the user via juju status. If the status-set command is not found then
+    assume this is juju < 1.23 and juju-log the message unstead.
+
+    workload_state -- valid juju workload state.
+    message        -- status update message
+    """
+    valid_states = ['maintenance', 'blocked', 'waiting', 'active']
+    if workload_state not in valid_states:
+        raise ValueError(
+            '{!r} is not a valid workload state'.format(workload_state)
+        )
+    cmd = ['status-set', workload_state, message]
+    try:
+        ret = subprocess.call(cmd)
+        if ret == 0:
+            return
+    except OSError as e:
+        if e.errno != errno.ENOENT:
+            raise
+    log_message = 'status-set failed: {} {}'.format(workload_state,
+                                                    message)
+    log(log_message, level='INFO')
+
+
+def status_get():
+    """Retrieve the previously set juju workload state
+
+    If the status-set command is not found then assume this is juju < 1.23 and
+    return 'unknown'
+    """
+    cmd = ['status-get']
+    try:
+        raw_status = subprocess.check_output(cmd, universal_newlines=True)
+        status = raw_status.rstrip()
+        return status
+    except OSError as e:
+        if e.errno == errno.ENOENT:
+            return 'unknown'
+        else:
+            raise
+
+
+def translate_exc(from_exc, to_exc):
+    def inner_translate_exc1(f):
+        def inner_translate_exc2(*args, **kwargs):
+            try:
+                return f(*args, **kwargs)
+            except from_exc:
+                raise to_exc
+
+        return inner_translate_exc2
+
+    return inner_translate_exc1
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def is_leader():
+    """Does the current unit hold the juju leadership
+
+    Uses juju to determine whether the current unit is the leader of its peers
+    """
+    cmd = ['is-leader', '--format=json']
+    return json.loads(subprocess.check_output(cmd).decode('UTF-8'))
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def leader_get(attribute=None):
+    """Juju leader get value(s)"""
+    cmd = ['leader-get', '--format=json'] + [attribute or '-']
+    return json.loads(subprocess.check_output(cmd).decode('UTF-8'))
+
+
+@translate_exc(from_exc=OSError, to_exc=NotImplementedError)
+def leader_set(settings=None, **kwargs):
+    """Juju leader set value(s)"""
+    log("Juju leader-set '%s'" % (settings), level=DEBUG)
+    cmd = ['leader-set']
+    settings = settings or {}
+    settings.update(kwargs)
+    for k, v in settings.iteritems():
+        if v is None:
+            cmd.append('{}='.format(k))
+        else:
+            cmd.append('{}={}'.format(k, v))
+    subprocess.check_call(cmd)
diff --git a/hooks/charmhelpers/core/host.py b/hooks/charmhelpers/core/host.py
index 830822af..0d2ab4b4 100644
--- a/hooks/charmhelpers/core/host.py
+++ b/hooks/charmhelpers/core/host.py
@@ -90,7 +90,7 @@ def service_available(service_name):
             ['service', service_name, 'status'],
             stderr=subprocess.STDOUT).decode('UTF-8')
     except subprocess.CalledProcessError as e:
-        return 'unrecognized service' not in e.output
+        return b'unrecognized service' not in e.output
     else:
         return True
 
diff --git a/hooks/charmhelpers/core/services/base.py b/hooks/charmhelpers/core/services/base.py
index c5534e4c..98d344e1 100644
--- a/hooks/charmhelpers/core/services/base.py
+++ b/hooks/charmhelpers/core/services/base.py
@@ -15,9 +15,9 @@
 # along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
-import re
 import json
-from collections import Iterable
+from inspect import getargspec
+from collections import Iterable, OrderedDict
 
 from charmhelpers.core import host
 from charmhelpers.core import hookenv
@@ -119,7 +119,7 @@ class ServiceManager(object):
         """
         self._ready_file = os.path.join(hookenv.charm_dir(), 'READY-SERVICES.json')
         self._ready = None
-        self.services = {}
+        self.services = OrderedDict()
         for service in services or []:
             service_name = service['service']
             self.services[service_name] = service
@@ -132,8 +132,8 @@ class ServiceManager(object):
         if hook_name == 'stop':
             self.stop_services()
         else:
-            self.provide_data()
             self.reconfigure_services()
+            self.provide_data()
         cfg = hookenv.config()
         if cfg.implicit_save:
             cfg.save()
@@ -145,15 +145,36 @@ class ServiceManager(object):
         A provider must have a `name` attribute, which indicates which relation
         to set data on, and a `provide_data()` method, which returns a dict of
         data to set.
+
+        The `provide_data()` method can optionally accept two parameters:
+
+          * ``remote_service`` The name of the remote service that the data will
+            be provided to.  The `provide_data()` method will be called once
+            for each connected service (not unit).  This allows the method to
+            tailor its data to the given service.
+          * ``service_ready`` Whether or not the service definition had all of
+            its requirements met, and thus the ``data_ready`` callbacks run.
+
+        Note that the ``provided_data`` methods are now called **after** the
+        ``data_ready`` callbacks are run.  This gives the ``data_ready`` callbacks
+        a chance to generate any data necessary for the providing to the remote
+        services.
         """
-        hook_name = hookenv.hook_name()
-        for service in self.services.values():
+        for service_name, service in self.services.items():
+            service_ready = self.is_ready(service_name)
             for provider in service.get('provided_data', []):
-                if re.match(r'{}-relation-(joined|changed)'.format(provider.name), hook_name):
-                    data = provider.provide_data()
-                    _ready = provider._is_ready(data) if hasattr(provider, '_is_ready') else data
-                    if _ready:
-                        hookenv.relation_set(None, data)
+                for relid in hookenv.relation_ids(provider.name):
+                    units = hookenv.related_units(relid)
+                    if not units:
+                        continue
+                    remote_service = units[0].split('/')[0]
+                    argspec = getargspec(provider.provide_data)
+                    if len(argspec.args) > 1:
+                        data = provider.provide_data(remote_service, service_ready)
+                    else:
+                        data = provider.provide_data()
+                    if data:
+                        hookenv.relation_set(relid, data)
 
     def reconfigure_services(self, *service_names):
         """
diff --git a/hooks/charmhelpers/fetch/__init__.py b/hooks/charmhelpers/fetch/__init__.py
index 792e629a..9a1a2515 100644
--- a/hooks/charmhelpers/fetch/__init__.py
+++ b/hooks/charmhelpers/fetch/__init__.py
@@ -158,7 +158,7 @@ def filter_installed_packages(packages):
 
 def apt_cache(in_memory=True):
     """Build and return an apt cache"""
-    import apt_pkg
+    from apt import apt_pkg
     apt_pkg.init()
     if in_memory:
         apt_pkg.config.set("Dir::Cache::pkgcache", "")
diff --git a/hooks/cinder_hooks.py b/hooks/cinder_hooks.py
index d420a6cd..6e706257 100755
--- a/hooks/cinder_hooks.py
+++ b/hooks/cinder_hooks.py
@@ -72,7 +72,7 @@ from charmhelpers.contrib.storage.linux.ceph import (
 )
 
 from charmhelpers.contrib.hahelpers.cluster import (
-    eligible_leader,
+    is_elected_leader,
     get_hacluster_config,
 )
 
@@ -192,7 +192,7 @@ def db_changed():
         juju_log('shared-db relation incomplete. Peer not ready?')
         return
     CONFIGS.write(CINDER_CONF)
-    if eligible_leader(CLUSTER_RES):
+    if is_elected_leader(CLUSTER_RES):
         # Bugs 1353135 & 1187508. Dbs can appear to be ready before the units
         # acl entry has been added. So, if the db supports passing a list of
         # permitted units then check if we're in the list.
@@ -212,7 +212,7 @@ def pgsql_db_changed():
         juju_log('pgsql-db relation incomplete. Peer not ready?')
         return
     CONFIGS.write(CINDER_CONF)
-    if eligible_leader(CLUSTER_RES):
+    if is_elected_leader(CLUSTER_RES):
         juju_log('Cluster leader, performing db sync')
         migrate_database()
 
diff --git a/hooks/cinder_utils.py b/hooks/cinder_utils.py
index a72eb624..9e0a06ec 100644
--- a/hooks/cinder_utils.py
+++ b/hooks/cinder_utils.py
@@ -45,7 +45,7 @@ from charmhelpers.core.host import (
 
 from charmhelpers.contrib.openstack.alternatives import install_alternative
 from charmhelpers.contrib.hahelpers.cluster import (
-    eligible_leader,
+    is_elected_leader,
 )
 
 from charmhelpers.contrib.storage.linux.utils import (
@@ -83,6 +83,9 @@ from charmhelpers.contrib.openstack.utils import (
     os_release,
 )
 
+from charmhelpers.core.decorators import (
+    retry_on_exception,
+)
 from charmhelpers.core.templating import render
 
 import cinder_contexts
@@ -488,6 +491,9 @@ def check_db_initialised():
             relation_set(**{CINDER_DB_INIT_ECHO_RKEY: init_id})
 
 
+# NOTE(jamespage): Retry deals with sync issues during one-shot HA deploys.
+#                  mysql might be restarting or suchlike.
+@retry_on_exception(5, base_delay=3, exc_type=subprocess.CalledProcessError)
 def migrate_database():
     'Runs cinder-manage to initialize a new database or migrate existing'
     cmd = ['cinder-manage', 'db', 'sync']
@@ -542,7 +548,7 @@ def do_openstack_upgrade(configs):
 
     # Stop/start services and migrate DB if leader
     [service_stop(s) for s in services()]
-    if eligible_leader(CLUSTER_RES):
+    if is_elected_leader(CLUSTER_RES):
         migrate_database()
     [service_start(s) for s in services()]
 
diff --git a/unit_tests/test_cinder_hooks.py b/unit_tests/test_cinder_hooks.py
index 1cbef574..53ca6d03 100644
--- a/unit_tests/test_cinder_hooks.py
+++ b/unit_tests/test_cinder_hooks.py
@@ -62,13 +62,14 @@ TO_PATCH = [
     'apt_install',
     'apt_update',
     'service_reload',
+    'service_restart',
     # charmhelpers.contrib.openstack.openstack_utils
     'configure_installation_source',
     'openstack_upgrade_available',
     'os_release',
     # charmhelpers.contrib.hahelpers.cluster_utils
     'canonical_url',
-    'eligible_leader',
+    'is_elected_leader',
     'get_hacluster_config',
     'execd_preinstall',
     'get_ipv6_addr',
@@ -240,7 +241,7 @@ class TestChangedHooks(CharmTestCase):
         self.relation_get.return_value = 'cinder/1 cinder/2'
         self.local_unit.return_value = 'cinder/0'
         self.CONFIGS.complete_contexts.return_value = ['shared-db']
-        self.eligible_leader.return_value = True
+        self.is_elected_leader.return_value = True
         hooks.hooks.execute(['hooks/shared-db-relation-changed'])
         self.assertFalse(self.migrate_database.called)
 
@@ -249,7 +250,7 @@ class TestChangedHooks(CharmTestCase):
         self.relation_get.return_value = None
         self.local_unit.return_value = 'cinder/0'
         self.CONFIGS.complete_contexts.return_value = ['shared-db']
-        self.eligible_leader.return_value = True
+        self.is_elected_leader.return_value = True
         hooks.hooks.execute(['hooks/shared-db-relation-changed'])
         self.assertFalse(self.migrate_database.called)
 
@@ -263,7 +264,7 @@ class TestChangedHooks(CharmTestCase):
         'It does not migrate database when not leader'
         self.relation_get.return_value = 'cinder/0 cinder/1'
         self.local_unit.return_value = 'cinder/0'
-        self.eligible_leader.return_value = False
+        self.is_elected_leader.return_value = False
         self.CONFIGS.complete_contexts.return_value = ['shared-db']
         hooks.hooks.execute(['hooks/shared-db-relation-changed'])
         self.CONFIGS.write.assert_called_with('/etc/cinder/cinder.conf')
@@ -271,7 +272,7 @@ class TestChangedHooks(CharmTestCase):
 
     def test_pgsql_db_changed_not_leader(self):
         'It does not migrate database when not leader'
-        self.eligible_leader.return_value = False
+        self.is_elected_leader.return_value = False
         self.CONFIGS.complete_contexts.return_value = ['pgsql-db']
         hooks.hooks.execute(['hooks/pgsql-db-relation-changed'])
         self.CONFIGS.write.assert_called_with('/etc/cinder/cinder.conf')
@@ -518,6 +519,7 @@ class TestJoinedHooks(CharmTestCase):
                   call('/etc/cinder/cinder.conf')]:
             self.assertIn(c, self.CONFIGS.write.call_args_list)
         self.set_ceph_env_variables.assert_called_with(service='cinder')
+        self.service_restart.assert_called_with('cinder-volume')
 
     @patch("cinder_hooks.relation_get", autospec=True)
     def test_ceph_changed_broker_nonzero_rc(self, mock_relation_get):
@@ -555,7 +557,7 @@ class TestJoinedHooks(CharmTestCase):
 
     def test_ceph_changed_no_leadership(self):
         '''It does not attempt to create ceph pool if not leader'''
-        self.eligible_leader.return_value = False
+        self.is_elected_leader.return_value = False
         self.service_name.return_value = 'cinder'
         self.ensure_ceph_keyring.return_value = True
         hooks.hooks.execute(['hooks/ceph-relation-changed'])
diff --git a/unit_tests/test_cinder_utils.py b/unit_tests/test_cinder_utils.py
index 3ab28800..719ffacf 100644
--- a/unit_tests/test_cinder_utils.py
+++ b/unit_tests/test_cinder_utils.py
@@ -38,7 +38,7 @@ TO_PATCH = [
     'os_release',
     'get_os_codename_install_source',
     'configure_installation_source',
-    'eligible_leader',
+    'is_elected_leader',
     'templating',
     'install_alternative',
     # fetch
@@ -501,7 +501,7 @@ class TestCinderUtils(CharmTestCase):
         self.config.side_effect = None
         self.config.return_value = 'cloud:precise-havana'
         services.return_value = ['cinder-api', 'cinder-volume']
-        self.eligible_leader.return_value = True
+        self.is_elected_leader.return_value = True
         self.get_os_codename_install_source.return_value = 'havana'
         configs = MagicMock()
         cinder_utils.do_openstack_upgrade(configs)
@@ -520,7 +520,7 @@ class TestCinderUtils(CharmTestCase):
         self.config.side_effect = None
         self.config.return_value = 'cloud:precise-havana'
         services.return_value = ['cinder-api', 'cinder-volume']
-        self.eligible_leader.return_value = False
+        self.is_elected_leader.return_value = False
         self.get_os_codename_install_source.return_value = 'havana'
         configs = MagicMock()
         cinder_utils.do_openstack_upgrade(configs)
diff --git a/unit_tests/test_cluster_hooks.py b/unit_tests/test_cluster_hooks.py
index f51676c1..62cea2f5 100644
--- a/unit_tests/test_cluster_hooks.py
+++ b/unit_tests/test_cluster_hooks.py
@@ -48,7 +48,7 @@ TO_PATCH = [
     # charmhelpers.contrib.openstack.openstack_utils
     'configure_installation_source',
     # charmhelpers.contrib.hahelpers.cluster_utils
-    'eligible_leader',
+    'is_elected_leader',
     'get_hacluster_config',
     # charmhelpers.contrib.network.ip
     'get_iface_for_address',