Add preconditions to pod/rs update retry func

pkg/util/deployment/deployment.go

@@ -187,8 +187,11 @@ func addHashKeyToRSAndPods(deployment *extensions.Deployment, c clientset.Interf
 	}))
 	rsUpdated := false
 	// 1. Add hash template label to the rs. This ensures that any newly created pods will have the new label.
-	if len(updatedRS.Spec.Template.Labels[extensions.DefaultDeploymentUniqueLabelKey]) == 0 {
+	updatedRS, rsUpdated, err = rsutil.UpdateRSWithRetries(c.Extensions().ReplicaSets(namespace), updatedRS,
-		updatedRS, rsUpdated, err = rsutil.UpdateRSWithRetries(c.Extensions().ReplicaSets(namespace), updatedRS, func(updated *extensions.ReplicaSet) {
+		func(updated *extensions.ReplicaSet) bool {
+			return updated.Spec.Template.Labels[extensions.DefaultDeploymentUniqueLabelKey] != hash
+		},
+		func(updated *extensions.ReplicaSet) {
 			updated.Spec.Template.Labels = labelsutil.AddLabel(updated.Spec.Template.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
 		})
 	if err != nil {
@@ -207,7 +210,7 @@ func addHashKeyToRSAndPods(deployment *extensions.Deployment, c clientset.Interf
 		// Return here and retry in the next sync loop.
 		return &rs, nil
 	}
-	}
+	glog.V(4).Infof("Observed the update of rs %s's pod template with hash %s.", rs.Name, hash)
 
 	// 2. Update all pods managed by the rs to have the new hash label, so they will be correctly adopted.
 	selector, err := unversioned.LabelSelectorAsSelector(updatedRS.Spec.Selector)
@@ -231,7 +234,11 @@ func addHashKeyToRSAndPods(deployment *extensions.Deployment, c clientset.Interf
 
 	// 3. Update rs label and selector to include the new hash label
 	// Copy the old selector, so that we can scrub out any orphaned pods
-	if updatedRS, rsUpdated, err = rsutil.UpdateRSWithRetries(c.Extensions().ReplicaSets(namespace), updatedRS, func(updated *extensions.ReplicaSet) {
+	if updatedRS, rsUpdated, err = rsutil.UpdateRSWithRetries(c.Extensions().ReplicaSets(namespace), updatedRS,
+		func(updated *extensions.ReplicaSet) bool {
+			return updated.Labels[extensions.DefaultDeploymentUniqueLabelKey] != hash || updated.Spec.Selector.MatchLabels[extensions.DefaultDeploymentUniqueLabelKey] != hash
+		},
+		func(updated *extensions.ReplicaSet) {
 			updated.Labels = labelsutil.AddLabel(updated.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
 			updated.Spec.Selector = labelsutil.AddLabelToSelector(updated.Spec.Selector, extensions.DefaultDeploymentUniqueLabelKey, hash)
 		}); err != nil {
@@ -264,7 +271,11 @@ func labelPodsWithHash(podList *api.PodList, rs *extensions.ReplicaSet, c client
 	for _, pod := range podList.Items {
 		// Only label the pod that doesn't already have the new hash
 		if pod.Labels[extensions.DefaultDeploymentUniqueLabelKey] != hash {
-			if _, podUpdated, err := podutil.UpdatePodWithRetries(c.Core().Pods(namespace), &pod, func(podToUpdate *api.Pod) {
+			if _, podUpdated, err := podutil.UpdatePodWithRetries(c.Core().Pods(namespace), &pod,
+				func(podToUpdate *api.Pod) bool {
+					return podToUpdate.Labels[extensions.DefaultDeploymentUniqueLabelKey] != hash
+				},
+				func(podToUpdate *api.Pod) {
 					podToUpdate.Labels = labelsutil.AddLabel(podToUpdate.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
 				}); err != nil {
 				return false, fmt.Errorf("error in adding template hash label %s to pod %+v: %s", hash, pod, err)

pkg/util/pod/pod.go

@@ -39,10 +39,11 @@ func GetPodTemplateSpecHash(template api.PodTemplateSpec) uint32 {
 // TODO: use client library instead when it starts to support update retries
 //       see https://github.com/kubernetes/kubernetes/issues/21479
 type updatePodFunc func(pod *api.Pod)
+type preconditionFunc func(pod *api.Pod) bool
 
-// UpdatePodWithRetries updates a pod with given applyUpdate function. Note that pod not found error is ignored.
+// UpdatePodWithRetries updates a pod with given applyUpdate function, when the given precondition holds. Note that pod not found error is ignored.
 // The returned bool value can be used to tell if the pod is actually updated.
-func UpdatePodWithRetries(podClient unversionedcore.PodInterface, pod *api.Pod, applyUpdate updatePodFunc) (*api.Pod, bool, error) {
+func UpdatePodWithRetries(podClient unversionedcore.PodInterface, pod *api.Pod, preconditionHold preconditionFunc, applyUpdate updatePodFunc) (*api.Pod, bool, error) {
 	var err error
 	var podUpdated bool
 	oldPod := pod
@@ -51,8 +52,11 @@ func UpdatePodWithRetries(podClient unversionedcore.PodInterface, pod *api.Pod,
 		if err != nil {
 			return false, err
 		}
+		if !preconditionHold(pod) {
+			glog.V(4).Infof("pod %s precondition doesn't hold, skip updating it.", pod.Name)
+			return true, nil
+		}
 		// Apply the update, then attempt to push it to the apiserver.
-		// TODO: add precondition for update
 		applyUpdate(pod)
 		if pod, err = podClient.Update(pod); err == nil {
 			// Update successful.

pkg/util/replicaset/replicaset.go

@@ -30,10 +30,11 @@ import (
 // TODO: use client library instead when it starts to support update retries
 //       see https://github.com/kubernetes/kubernetes/issues/21479
 type updateRSFunc func(rs *extensions.ReplicaSet)
+type preconditionFunc func(rs *extensions.ReplicaSet) bool
 
-// UpdateRSWithRetries updates a RS with given applyUpdate function. Note that RS not found error is ignored.
+// UpdateRSWithRetries updates a RS with given applyUpdate function, when the given precondition holds. Note that RS not found error is ignored.
 // The returned bool value can be used to tell if the RS is actually updated.
-func UpdateRSWithRetries(rsClient unversionedextensions.ReplicaSetInterface, rs *extensions.ReplicaSet, applyUpdate updateRSFunc) (*extensions.ReplicaSet, bool, error) {
+func UpdateRSWithRetries(rsClient unversionedextensions.ReplicaSetInterface, rs *extensions.ReplicaSet, preconditionHold preconditionFunc, applyUpdate updateRSFunc) (*extensions.ReplicaSet, bool, error) {
 	var err error
 	var rsUpdated bool
 	oldRs := rs
@@ -42,8 +43,11 @@ func UpdateRSWithRetries(rsClient unversionedextensions.ReplicaSetInterface, rs
 		if err != nil {
 			return false, err
 		}
+		if !preconditionHold(rs) {
+			glog.V(4).Infof("rs %s precondition doesn't hold, skip updating it.", rs.Name)
+			return true, nil
+		}
 		// Apply the update, then attempt to push it to the apiserver.
-		// TODO: add precondition for update
 		applyUpdate(rs)
 		if rs, err = rsClient.Update(rs); err == nil {
 			// Update successful.