controller: set unavailableReplicas correctly when scaling down

deployment_controller.go:299] Error syncing deployment e2e-tests-kubectl-2l7xx/e2e-test-nginx-deployment: Deployment.extensions "e2e-test-nginx-deployment" is invalid: status.unavailableReplicas: Invalid value: -1: must be greater than or equal to 0 The validation error above occurs usually when a Deployment is scaled down. In such a case we should default unavailableReplicas to 0 instead of making an invalid api call.

controller: set unavailableReplicas correctly when scaling down
c82cae85 · Michail Kargakis · fc361206 · c82cae85
Commit c82cae85 authored Dec 07, 2016 by Michail Kargakis
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sync.go pkg/controller/deployment/sync.go +7 -1

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--- a/pkg/controller/deployment/sync.go
+++ b/pkg/controller/deployment/sync.go
@@ -597,6 +597,12 @@ func (dc *DeploymentController) syncDeploymentStatus(allRSs []*extensions.Replic
 func (dc *DeploymentController) calculateStatus(allRSs []*extensions.ReplicaSet, newRS *extensions.ReplicaSet, deployment *extensions.Deployment) extensions.DeploymentStatus {
 	availableReplicas := deploymentutil.GetAvailableReplicaCountForReplicaSets(allRSs)
 	totalReplicas := deploymentutil.GetReplicaCountForReplicaSets(allRSs)
+	unavailableReplicas := totalReplicas - availableReplicas
+	// If unavailableReplicas is negative, then that means the Deployment has more available replicas running than
+	// desired, eg. whenever it scales down. In such a case we should simply default unavailableReplicas to zero.
+	if unavailableReplicas < 0 {
+		unavailableReplicas = 0
+	}

 	if availableReplicas >= *(deployment.Spec.Replicas)-deploymentutil.MaxUnavailable(*deployment) {
 		minAvailability := deploymentutil.NewDeploymentCondition(extensions.DeploymentAvailable, v1.ConditionTrue, deploymentutil.MinimumReplicasAvailable, "Deployment has minimum availability.")
@@ -612,7 +618,7 @@ func (dc *DeploymentController) calculateStatus(allRSs []*extensions.ReplicaSet,
 		Replicas:            deploymentutil.GetActualReplicaCountForReplicaSets(allRSs),
 		UpdatedReplicas:     deploymentutil.GetActualReplicaCountForReplicaSets([]*extensions.ReplicaSet{newRS}),
 		AvailableReplicas:   availableReplicas,
-		UnavailableReplicas: totalReplicas - availableReplicas,
+		UnavailableReplicas: unavailableReplicas,
 		Conditions:          deployment.Status.Conditions,
 	}
 }