Rebase on python-redux work.

hooks/charmhelpers/contrib/openstack/context.py

@@ -1,3 +1,4 @@
+import json
 import os
 
 from base64 import b64decode
@@ -21,6 +22,7 @@ from charmhelpers.core.hookenv import (
     related_units,
     unit_get,
     unit_private_ip,
+    ERROR,
     WARNING,
 )
 
@@ -431,3 +433,84 @@ class OSConfigFlagContext(OSContextGenerator):
                 flags[k.strip()] = v
             ctxt = {'user_config_flags': flags}
             return ctxt
+
+
+class SubordinateConfigContext(OSContextGenerator):
+    """
+    Responsible for inspecting relations to subordinates that
+    may be exporting required config via a json blob.
+
+    The subordinate interface allows subordinates to export their
+    configuration requirements to the principle for multiple config
+    files and multiple serivces.  Ie, a subordinate that has interfaces
+    to both glance and nova may export to following yaml blob as json:
+
+        glance:
+            /etc/glance/glance-api.conf:
+                sections:
+                    DEFAULT:
+                        - [key1, value1]
+            /etc/glance/glance-registry.conf:
+                    MYSECTION:
+                        - [key2, value2]
+        nova:
+            /etc/nova/nova.conf:
+                sections:
+                    DEFAULT:
+                        - [key3, value3]
+
+
+    It is then up to the principle charms to subscribe this context to
+    the service+config file it is interestd in.  Configuration data will
+    be available in the template context, in glance's case, as:
+        ctxt = {
+            ... other context ...
+            'subordinate_config': {
+                'DEFAULT': {
+                    'key1': 'value1',
+                },
+                'MYSECTION': {
+                    'key2': 'value2',
+                },
+            }
+        }
+
+    """
+    def __init__(self, service, config_file, interface):
+        """
+        :param service     : Service name key to query in any subordinate
+                             data found
+        :param config_file : Service's config file to query sections
+        :param interface   : Subordinate interface to inspect
+        """
+        self.service = service
+        self.config_file = config_file
+        self.interface = interface
+
+    def __call__(self):
+        ctxt = {}
+        for rid in relation_ids(self.interface):
+            sub_config = relation_get('subordinate_config', relaton_id=rid)
+            if sub_config and sub_config != '':
+                try:
+                    sub_config = json.loads(sub_config)
+                except:
+                    log('Could not parse JSON from subordinate_config setting '
+                        'from %s' % rid, level=ERROR)
+
+                if self.service not in sub_config:
+                    log('Found subordinate_config on %s but it contained'
+                        'nothing for %s service' % (rid, self.service))
+                    continue
+
+                sub_config = sub_config[self.service]
+                if self.config_file not in sub_config:
+                    log('Found subordinate_config on %s but it contained'
+                        'nothing for %s' % (rid, self.config_file))
+                    continue
+
+                sub_config = sub_config[self.config_file]
+                for k, v in sub_config.iteritems():
+                    ctxt[k] = v
+
+        return ctxt

hooks/nova_cc_hooks.py

@@ -396,6 +396,11 @@ def configure_https():
         identity_joined(rid=rid)
 
 
+@hooks.hook()
+def nova_vmware_relation_joined():
+    relation_set(network_manager=network_manager())
+
+
 def main():
     try:
         hooks.execute(sys.argv)

hooks/nova_cc_utils.py

@@ -84,6 +84,11 @@ BASE_RESOURCE_MAP = OrderedDict([
                      context.SharedDBContext(relation_prefix='nova'),
                      context.ImageServiceContext(),
                      context.OSConfigFlagContext(),
+                     context.SubordinateConfigContext(
+                         interface='nova-vmware',
+                         service='nova',
+                         config_file=NOVA_CONF,
+                     ),
                      nova_cc_context.HAProxyContext(),
                      nova_cc_context.IdentityServiceContext(),
                      nova_cc_context.VolumeServiceContext(),

metadata.yaml

@@ -27,7 +27,7 @@ requires:
   ha:
     interface: hacluster
     scope: container
-  vmware:
+  nova-vmware:
     interface: nova-vmware
     scope: container
 peers: