Prometheus: Use volume claims to support RWO storage class

This PS uses volumeClaimTemplates to provide multiple
pvcs and pvs to prometheus statefulset's multiple pods.
This gives ability to provide read-write-many access
backend by a read-write-once storage class.

Change-Id: I53d1b866c0c87f0833941b612d3acfbe5742744f

prometheus/templates/pvc.yaml

@@ -1,31 +0,0 @@
-{{/*
-Copyright 2017 The Openstack-Helm Authors.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-   http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/}}
-
-{{- if .Values.manifests.pvc }}
-{{- $envAll := . }}
----
-kind: PersistentVolumeClaim
-apiVersion: v1
-metadata:
-  name: {{ .Values.storage.pvc.name }}
-spec:
-  accessModes:
-    - {{ .Values.storage.pvc.access_mode }}
-  resources:
-    requests:
-      storage: {{ .Values.storage.requests.storage }}
-  storageClassName: {{ .Values.storage.storage_class }}
-{{- end }}

prometheus/templates/statefulset.yaml

@@ -158,13 +158,19 @@ spec:
           configMap:
             name: prometheus-bin
             defaultMode: 0555
-        {{- if .Values.storage.enabled }}
-        - name: storage
-          persistentVolumeClaim:
-            claimName: {{ .Values.storage.pvc.name }}
-        {{- else }}
+{{ if $mounts_prometheus.volumes }}{{ toYaml $mounts_prometheus.volumes | indent 8 }}{{ end }}
+{{- if not .Values.storage.enabled }}
         - name: storage
           emptyDir: {}
-        {{- end }}
-{{ if $mounts_prometheus.volumes }}{{ toYaml $mounts_prometheus.volumes | indent 8 }}{{ end }}
+{{- else }}
+  volumeClaimTemplates:
+    - metadata:
+        name: storage
+      spec:
+        accessModes: {{ .Values.storage.pvc.access_mode }}
+        resources:
+          requests:
+            storage: {{ .Values.storage.requests.storage  }}
+        storageClassName: {{ .Values.storage.storage_class }}
+{{- end }}
 {{- end }}

prometheus/values.yaml

@@ -165,7 +165,7 @@ storage:
   enabled: true
   pvc:
     name: prometheus-pvc
-    access_mode: ReadWriteMany
+    access_mode: [ "ReadWriteOnce" ]
   requests:
     storage: 5Gi
   storage_class: general