Check rolling updates using controller revisions.

Compare pods controller revisions with the one for the statefulset
to determine whether the pod is running the latest revision and,
therefore, no rolling update is necessary. This is performed only
during the operator start, afterwards the rolling update status
that is stored locally in the cluster structure is used for all
rolling update decisions.

pkg/cluster/cluster.go

@@ -71,12 +71,13 @@ type Cluster struct {
 	deleteOptions    *metav1.DeleteOptions
 	podEventsQueue   *cache.FIFO
 
-	teamsAPIClient   teams.Interface
-	oauthTokenGetter OAuthTokenGetter
-	KubeClient       k8sutil.KubernetesClient //TODO: move clients to the better place?
-	currentProcess   spec.Process
-	processMu        sync.RWMutex // protects the current operation for reporting, no need to hold the master mutex
-	specMu           sync.RWMutex // protects the spec for reporting, no need to hold the master mutex
+	teamsAPIClient       teams.Interface
+	oauthTokenGetter     OAuthTokenGetter
+	KubeClient           k8sutil.KubernetesClient //TODO: move clients to the better place?
+	currentProcess       spec.Process
+	processMu            sync.RWMutex // protects the current operation for reporting, no need to hold the master mutex
+	specMu               sync.RWMutex // protects the spec for reporting, no need to hold the master mutex
+	pendingRollingUpdate *bool        // indicates the cluster needs a rolling update
 }
 
 type compareStatefulsetResult struct {
@@ -109,10 +110,11 @@ func New(cfg Config, kubeClient k8sutil.KubernetesClient, pgSpec spec.Postgresql
 			Secrets:   make(map[types.UID]*v1.Secret),
 			Services:  make(map[PostgresRole]*v1.Service),
 			Endpoints: make(map[PostgresRole]*v1.Endpoints)},
-		userSyncStrategy: users.DefaultUserSyncStrategy{},
-		deleteOptions:    &metav1.DeleteOptions{OrphanDependents: &orphanDependents},
-		podEventsQueue:   podEventsQueue,
-		KubeClient:       kubeClient,
+		userSyncStrategy:     users.DefaultUserSyncStrategy{},
+		deleteOptions:        &metav1.DeleteOptions{OrphanDependents: &orphanDependents},
+		podEventsQueue:       podEventsQueue,
+		KubeClient:           kubeClient,
+		pendingRollingUpdate: nil,
 	}
 	cluster.logger = logger.WithField("pkg", "cluster").WithField("cluster-name", cluster.clusterName())
 	cluster.teamsAPIClient = teams.NewTeamsAPI(cfg.OpConfig.TeamsAPIUrl, logger)
@@ -215,6 +217,7 @@ func (c *Cluster) Create() error {
 	}()
 
 	c.setStatus(spec.ClusterStatusCreating)
+	c.setPendingRollingUpgrade(false)
 
 	for _, role := range []PostgresRole{Master, Replica} {