Few changes:

- Add support for shared secret for ceilometer's signed messages
- Refactor MongoDBContext to be a bit more clean
- Specify replicaSet and readPreference parameters in the mongodb url

hooks/ceilometer_contexts.py

@@ -1,5 +1,4 @@
 import os
-import uuid
 from charmhelpers.core.hookenv import (
     relation_ids,
     relation_get,
@@ -32,66 +31,52 @@ class MongoDBContext(OSContextGenerator):
     interfaces = ['mongodb']
 
     def __call__(self):
-        hostnames = []
-        port = None
+        mongo_servers = []
         replset = None
-        # TODO(wolsen) add a check in which will only execute this on a
-        # supported level of ceilometer code, which would be a specific version
-        # of the code, not just icehouse.
-        support = os_release('ceilometer-api') >= 'icehouse'
+        use_replset = os_release('ceilometer-api') >= 'icehouse'
         
         for relid in relation_ids('shared-db'):
-            for unit in related_units(relid):
-                replset = relation_get('replset', unit, relid)
+            rel_units = related_units(relid)
+            use_replset = use_replset and (len(rel_units) > 1)
+            
+            for unit in rel_units:
                 host = relation_get('hostname', unit, relid)
-                if port is None:
-                    port = relation_get('port', unit, relid)
+                port = relation_get('port', unit, relid)
                 
-                # If replica sets aren't used or aren't supported by ceilometer
-                # then stop looping if there is enough data 
-                if not support or not replset:
-                    if context_complete({'db_host': host, 'db_port': port}):
-                        hostnames.append(host)
-                        break
+                if not use_replset:
+                    conf = {
+                        "db_host": host,
+                        "db_port": port,
+                        "db_name": CEILOMETER_DB
+                    }
+                    
+                    if context_complete(conf):
+                        return conf
                 else:
-                    hostnames.append('{}:{}'.format(host, port))
-
-        # If there aren't any hosts, then there's no real configuration
-        # to fill in here, so bail early
-        if port is None or port == '':
-            return {}
+                    if replset is None:
+                        replset = relation_get('replset', unit, relid)
+                    
+                    mongo_servers.append('{}:{}'.format(host, port))
         
-        conf = {
-            'db_host': ','.join(hostnames),
-            'db_port': port,
-            'db_name': CEILOMETER_DB
-        }
+        if mongo_servers:
+            conf = {
+                'db_mongo_servers': ','.join(mongo_servers),
+                'db_name': CEILOMETER_DB,
+                'db_replset': replset
+            }
+            return conf
 
-        if replset:
-            conf['db_replset'] = replset
+        return {}
 
-        return conf
-
-
-SHARED_SECRET = "/etc/ceilometer/secret.txt"
-
-
-def get_shared_secret():
-    secret = None
-    if not os.path.exists(SHARED_SECRET):
-        secret = str(uuid.uuid4())
-        with open(SHARED_SECRET, 'w') as secret_file:
-            secret_file.write(secret)
-    else:
-        with open(SHARED_SECRET, 'r') as secret_file:
-            secret = secret_file.read().strip()
-    return secret
 
 CEILOMETER_PORT = 8777
 
 
 class CeilometerContext(OSContextGenerator):
     def __call__(self):
+        # Lazy-import to avoid a circular dependency in the imports
+        from ceilometer_utils import get_shared_secret
+
         ctxt = {
             'port': CEILOMETER_PORT,
             'metering_secret': get_shared_secret()

hooks/ceilometer_hooks.py

@@ -31,7 +31,9 @@ from ceilometer_utils import (
     register_configs,
     restart_map,
     get_ceilometer_context,
-    do_openstack_upgrade
+    get_shared_secret,
+    do_openstack_upgrade,
+    set_shared_secret
 )
 from ceilometer_contexts import CEILOMETER_PORT
 from charmhelpers.contrib.openstack.ip import (
@@ -43,7 +45,8 @@ from charmhelpers.contrib.network.ip import (
     get_netmask_for_address
 )
 from charmhelpers.contrib.hahelpers.cluster import (
-    get_hacluster_config
+    get_hacluster_config,
+    is_elected_leader
 )
 
 hooks = Hooks()
@@ -109,11 +112,29 @@ def upgrade_charm():
     any_changed()
 
 
-@hooks.hook('cluster-relation-joined',
-            'cluster-relation-changed',
+@hooks.hook('cluster-relation-joined')
+@restart_on_change(restart_map(), stopstart=True)
+def cluster_joined():
+    vip = get_hacluster_config()['vip'].split()[0]
+    resource = 'res_ceilometer_{}_vip'.format(get_iface_for_address(vip))
+    
+    # If this node is the elected leader then share our secret with other nodes
+    if is_elected_leader(resource):
+        relation_set(shared_secret=get_shared_secret())
+
+    CONFIGS.write_all()
+
+
+@hooks.hook('cluster-relation-changed',
             'cluster-relation-departed')
 @restart_on_change(restart_map(), stopstart=True)
 def cluster_changed():
+    shared_secret = relation_get('shared_secret')
+    if shared_secret is None or shared_secret.strip() == '':
+        log('waiting for shared secret to be provided by leader')
+    elif not shared_secret == get_shared_secret():
+        set_shared_secret(shared_secret)
+    
     CONFIGS.write_all()
 
 

hooks/ceilometer_utils.py

@@ -1,4 +1,5 @@
 import os
+import uuid
 
 from collections import OrderedDict
 
@@ -84,6 +85,8 @@ CONFIG_FILES = OrderedDict([
 
 TEMPLATES = 'templates'
 
+SHARED_SECRET = "/etc/ceilometer/secret.txt"
+
 
 def register_configs():
     """
@@ -171,3 +174,28 @@ def get_packages():
             >= 'icehouse'):
         packages = packages + ICEHOUSE_PACKAGES
     return packages
+
+
+def get_shared_secret():
+    """
+    Returns the current shared secret for the ceilometer node. If the shared
+    secret does not exist, this method will generate one.
+    """
+    secret = None
+    if not os.path.exists(SHARED_SECRET):
+        secret = str(uuid.uuid4())
+        set_shared_secret(secret)
+    else:
+        with open(SHARED_SECRET, 'r') as secret_file:
+            secret = secret_file.read().strip()
+    return secret
+
+
+def set_shared_secret(secret):
+    """
+    Sets the shared secret which is used to sign ceilometer messages.
+    
+    :param secret: the secret to set
+    """
+    with open(SHARED_SECRET, 'w') as secret_file:
+        secret_file.write(secret)

templates/icehouse/ceilometer.conf

@@ -18,7 +18,7 @@ os_username = {{ admin_user }}
 os_password = {{ admin_password }}
 [database]
 {% if db_replset: -%}
-connection = mongodb://{{ db_host }}/{{ db_name }}?readPreference=primaryPreferred
+connection = mongodb://{{ db_mongo_servers }}/{{ db_name }}?readPreference=primaryPreferred&replicaSet={{ db_replset }}
 mongodb_replica_set = {{ db_replset }}
 {% else -%}
 connection = mongodb://{{ db_host }}:{{ db_port }}/{{ db_name }}