RabbitMQ add preStop and prep 3.8.x feature flag

This ps updates the following:
- Add preStop action to allow rabbitmq node a chance to more
  graceful shutdown
- Add support for RABBITMQ_FEATURE_FLAG in preparation for
  future 3.8.x upgrade.

Change-Id: I25d1e4fdb9dee370382e97a5a97b2b098f5ef11f

rabbitmq/Chart.yaml

@@ -15,6 +15,6 @@ apiVersion: v1
 appVersion: v3.7.26
 description: OpenStack-Helm RabbitMQ
 name: rabbitmq
-version: 0.1.12
+version: 0.1.13
 home: https://github.com/rabbitmq/rabbitmq-server
 ...

rabbitmq/templates/statefulset.yaml

@@ -212,6 +212,10 @@ spec:
               value: "{{ tuple "oslo_messaging" "internal" "amqp" . | include "helm-toolkit.endpoints.endpoint_port_lookup" }}"
             - name: PORT_CLUSTERING
               value: "{{ add (tuple "oslo_messaging" "internal" "amqp" . | include "helm-toolkit.endpoints.endpoint_port_lookup") 20000 }}"
+{{- if ne (.Values.conf.feature_flags | default "") "default" }}
+            - name: RABBITMQ_FEATURE_FLAGS
+              value: "{{ .Values.conf.feature_flags }}"
+{{- end }}
           readinessProbe:
             initialDelaySeconds: 10
             timeoutSeconds: 10
@@ -224,6 +228,12 @@ spec:
             exec:
               command:
               - /tmp/rabbitmq-liveness.sh
+          lifecycle:
+            preStop:
+              exec:
+                command:
+                  - rabbitmqctl
+                  - stop_app
           volumeMounts:
             - name: pod-tmp
               mountPath: /tmp

rabbitmq/values.yaml

@@ -195,6 +195,11 @@ conf:
     management.listener.port: null
   rabbitmq_exporter:
     rabbit_timeout: 30
+  # Feature Flags is introduced in RabbitMQ 3.8.0
+  # To deploy with standard list of feature, leave as default
+  # To deploy with specific feature, separate each feature with comma
+  # To deploy with all features disabled, leave blank or empty
+  feature_flags: default
 dependencies:
   dynamic:
     common:

releasenotes/notes/rabbitmq.yaml

@@ -12,4 +12,5 @@ rabbitmq:
   - 0.1.10 Set separate for HTTPS
   - 0.1.11 Add TLS support for helm test
   - 0.1.12 Added helm hook post-install and post-upgrade for rabbitmq wait cluster job
+  - 0.1.13 Add prestop action and version 3.8.x upgrade prep
 ...