Ceilometer: Enable oslo.cache backend

Ceilometer currently supports usage of oslo.cache backend to cache
resource data in Gnocchi publisher. This change enables the cache
backend so that the resource cache is shared across multiple process
using the shared memcached backend instead of being stored in local
process.

Conflicts:
	deployment/ceilometer/ceilometer-base-container-puppet.yaml

Depends-on: https://review.opendev.org/898202
Change-Id: I06833a88208e606313549dacbd5dc4766bbfb7fc
(cherry picked from commit 8a7e41170e839cd9b9e9519ad6ca0d007beab333)

deployment/ceilometer/ceilometer-base-container-puppet.yaml

@@ -75,6 +75,18 @@ parameters:
     default: 'ceilometer-low-rate'
     type: string
     description: (DEPRECATED) archive policy to use with gnocchi backend
+  EnableCache:
+    description: Enable caching with memcached
+    type: boolean
+    default: true
+  MemcachedTLS:
+    default: false
+    description: Set to True to enable TLS on Memcached service.
+                 Because not all services support Memcached TLS, during the
+                 migration period, Memcached will listen on 2 ports - on the
+                 port set with MemcachedPort parameter (above) and on 11211,
+                 without TLS.
+    type: boolean
 
 parameter_groups:
 - label: deprecated
@@ -86,6 +98,12 @@ parameter_groups:
   parameters:
   - GnocchiArchivePolicy
 
+conditions:
+  tls_cache_enabled:
+    and:
+      - {get_param: EnableCache}
+      - {get_param: MemcachedTLS}
+
 outputs:
   role_data:
     description: Role data for the Ceilometer role.
@@ -114,6 +132,13 @@ outputs:
             ceilometer::snmpd_readonly_user_password: {get_param: SnmpdReadonlyUserPassword}
             ceilometer::host: "%{hiera('fqdn_canonical')}"
             ceilometer::rabbit_heartbeat_in_pthread: false
+            ceilometer::cache::enabled: {get_param: EnableCache}
+            ceilometer::cache::tls_enabled: {get_param: MemcachedTLS}
+          - if:
+              - tls_cache_enabled
+              - ceilometer::cache::backend: 'dogpile.cache.pymemcache'
+                ceilometer::cache::enable_socket_keepalive: true
+              - ceilometer::cache::backend: 'dogpile.cache.memcached'
       service_config_settings:
         keystone:
           # Enable default notification queue