Add Prometheus alerts

Change-Id: Ia6873c44f4e5b179a6c4a545fbf4b45c978812ea

galera/meta/prometheus.yml

@@ -0,0 +1,22 @@
+{% raw %}
+server:
+  alert:
+    GaleraNodeNotReady:
+      if: 'mysql_wsrep_ready != 1'
+      for: 1m
+      labels:
+        severity: warning
+        service: mysql
+      annotations:
+        summary: 'Galera on {{ $labels.host }} not ready'
+        description: 'The Galera service on {{ $labels.host }} is not ready to serve queries.'
+    GaleraNodeNotConnected:
+      if: 'mysql_wsrep_connected != 1'
+      for: 1m
+      labels:
+        severity: warning
+        service: mysql
+      annotations:
+        summary: 'Galera on {{ $labels.host }} not connected'
+        description: 'The Galera service on {{ $labels.host }} is not connected to the cluster.'
+{% endraw %}

metadata/service/support.yml

@@ -13,5 +13,7 @@ parameters:
         enabled: true
       grafana:
         enabled: true
+      prometheus:
+        enabled: true
       telegraf:
         enabled: true