Fix an issue where creating a Coherence deployment with volume claim templates, or enabling persistence with a PVC, causes the Operator to keep continually re-reconciling and patching the StatefulSet. This does not actually change the StatefulSet or affect the running cluster but the Operator is needlessly causing update events.

Author: thegridman

go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/operator-framework/operator-sdk v0.18.0
 	github.com/pborman/uuid v1.2.0
 	github.com/pkg/errors v0.9.1
-	github.com/shopspring/decimal v0.0.0-20180709203117-cd690d0c9e24
 	github.com/shuLhan/go-bindata v3.4.0+incompatible // indirect
 	github.com/spf13/pflag v1.0.5
 	github.com/tebeka/go2xunit v1.4.10

pkg/controller/statefulset/statefulset_controller.go

@@ -288,10 +288,13 @@ func (in *ReconcileStatefulSet) patchStatefulSet(deployment *coh.Coherence, curr
 	name := current.GetName()
 	original, _ := storage.GetPrevious().GetResource(coh.ResourceTypeStatefulSet, name)
 
-	// We NEVER change the replicas or Phase in an update.
+	// We NEVER change the replicas or Status in an update.
 	// Replicas is handled by scaling so we always set the desired replicas to match the current replicas
 	desired.Spec.Replicas = current.Spec.Replicas
+	// We need to ensure we do not create a patch due to differences in StatefulSet Status
 	desired.Status = current.Status
+	// If the StatefulSet has PVs we need to ensure we do not create a patch due to ignorable differences in PV
+	in.mergeVolumeClaims(desired, current)
 
 	// a callback function that the 3-way patch method will call just before it applies a patch
 	callback := func() {
@@ -315,6 +318,37 @@ func (in *ReconcileStatefulSet) patchStatefulSet(deployment *coh.Coherence, curr
 	return patched, err
 }
 
+// If the desired StatefulSet has PVs update the desired PV to avid needless merges
+func (in *ReconcileStatefulSet) mergeVolumeClaims(desired, current *appsv1.StatefulSet) {
+	if len(desired.Spec.VolumeClaimTemplates) == 0 {
+		return
+	}
+
+	// Make a map of current PVs by name
+	m := make(map[string]corev1.PersistentVolumeClaim)
+	for _, pv := range current.Spec.VolumeClaimTemplates {
+		m[pv.Name] = pv
+	}
+
+	dfltVolumeMode := corev1.PersistentVolumeFilesystem
+
+	for i, pv := range desired.Spec.VolumeClaimTemplates {
+		currentPV, found := m[pv.Name]
+		if found {
+			// Update the desired PV statuses
+			pv.Status = currentPV.Status
+
+			// Set the desired volume mode to the default if it is not set
+			if pv.Spec.VolumeMode == nil {
+				pv.Spec.VolumeMode = &dfltVolumeMode
+			}
+
+			// set the updated PV back into the desired array
+			desired.Spec.VolumeClaimTemplates[i] = pv
+		}
+	}
+}
+
 // Scale will scale a StatefulSet up or down
 func (in *ReconcileStatefulSet) scale(deployment *coh.Coherence, sts *appsv1.StatefulSet, current, desired int32) (reconcile.Result, error) {
 	// if the StatefulSet is not stable we cannot scale (e.g. it might already be in the middle of a rolling upgrade)