bug 1420538. Allow users to set supplementalGroup for Cassandra

roles/openshift_metrics/defaults/main.yaml

@@ -23,6 +23,7 @@ openshift_metrics_cassandra_limits_cpu: null
 openshift_metrics_cassandra_requests_memory: 1G
 openshift_metrics_cassandra_requests_cpu: null
 openshift_metrics_cassandra_nodeselector: ""
+openshift_metrics_cassandra_storage_group: 65534
 
 openshift_metrics_heapster_standalone: False
 openshift_metrics_heapster_limits_memory: 3.75G

roles/openshift_metrics/templates/hawkular_cassandra_rc.j2

@@ -19,6 +19,9 @@ spec:
         type: hawkular-cassandra
     spec:
       serviceAccount: cassandra
+      securityContext:
+        supplementalGroups:
+        - {{openshift_metrics_cassandra_storage_group}}
 {% if node_selector is iterable and node_selector | length > 0 %}
       nodeSelector:
 {% for key, value in node_selector.iteritems() %}