Store hash to determine when pod spec changes

Comparing the desired pod spec to the current pod spec is not reliable as
the spec can be mutated by k8s e.g to add volume mount for a service account
or to add the default nodeselector from the namespace/cluster on OpenShift

Instead store a hash of the original pod spec as an annotation and compare
this to the hash of the current desired pod spec to determine if the spec
has changed.

controllers/client/openstackclient_controller.go

@@ -45,6 +45,7 @@ import (
 	"github.com/openstack-k8s-operators/lib-common/modules/common/configmap"
 	"github.com/openstack-k8s-operators/lib-common/modules/common/env"
 	helper "github.com/openstack-k8s-operators/lib-common/modules/common/helper"
+	"github.com/openstack-k8s-operators/lib-common/modules/common/labels"
 	common_rbac "github.com/openstack-k8s-operators/lib-common/modules/common/rbac"
 	"github.com/openstack-k8s-operators/lib-common/modules/common/tls"
 	telemetryv1 "github.com/openstack-k8s-operators/telemetry-operator/api/v1beta1"
@@ -307,17 +308,23 @@ func (r *OpenStackClientReconciler) Reconcile(ctx context.Context, req ctrl.Requ
 
 	spec := openstackclient.ClientPodSpec(ctx, instance, helper, configVarsHash)
 
+	podSpecHash, err := util.ObjectHash(spec)
+	if err != nil {
+		return ctrl.Result{}, err
+	}
+
+	podSpecAnnotation := labels.GetGroupLabel("openstackclient") + "/pod-spec-hash"
+
 	op, err := controllerutil.CreateOrPatch(ctx, r.Client, osclient, func() error {
 		isPodUpdate := !osclient.ObjectMeta.CreationTimestamp.IsZero()
-		if !isPodUpdate {
+		currentPodSpecHash, hasPodSpecHash := osclient.Annotations[podSpecAnnotation]
+		if !isPodUpdate || (hasPodSpecHash && currentPodSpecHash != podSpecHash) {
 			osclient.Spec = spec
-		} else {
-			osclient.Spec.Containers[0].Env = spec.Containers[0].Env
-			osclient.Spec.NodeSelector = spec.NodeSelector
-			osclient.Spec.Containers[0].Image = instance.Spec.ContainerImage
 		}
-
 		osclient.Labels = util.MergeStringMaps(osclient.Labels, clientLabels)
+		osclient.Annotations = util.MergeStringMaps(map[string]string{
+			podSpecAnnotation: podSpecHash,
+		}, osclient.Annotations)
 
 		err = controllerutil.SetControllerReference(instance, osclient, r.Scheme)
 		if err != nil {