fix: we do not need a deployment nor hpa if we migrate

Signed-off-by: Sandor Szücs <sandor.szuecs@zalando.de>

Author: szuecs

pkg/core/stack_resources.go

@@ -191,6 +191,10 @@ func (sc *StackContainer) selector() map[string]string {
 // "zalando.org/forward-backend", the deployment will be set to
 // replicas 1.
 func (sc *StackContainer) GenerateDeployment() *appsv1.Deployment {
+	if _, clusterMigration := sc.Stack.Annotations[forwardBackendAnnotation]; clusterMigration {
+		return nil
+	}
+
 	stack := sc.Stack
 
 	desiredReplicas := sc.stackReplicas
@@ -246,11 +250,6 @@ func (sc *StackContainer) GenerateDeployment() *appsv1.Deployment {
 		deployment.Spec.Strategy = *strategy
 	}
 
-	if _, clusterMigration := sc.Stack.Annotations[forwardBackendAnnotation]; clusterMigration {
-		i := int32(1)
-		deployment.Spec.Replicas = &i
-	}
-
 	return deployment
 }
 
@@ -262,6 +261,10 @@ func (sc *StackContainer) GenerateHPA() (
 	*autoscaling.HorizontalPodAutoscaler,
 	error,
 ) {
+	if _, clusterMigration := sc.Stack.Annotations[forwardBackendAnnotation]; clusterMigration {
+		return nil, nil
+	}
+
 	autoscalerSpec := sc.Stack.Spec.StackSpec.Autoscaler
 	trafficWeight := sc.actualTrafficWeight
 
@@ -312,12 +315,6 @@ func (sc *StackContainer) GenerateHPA() (
 		result.Spec.MinReplicas = &pr
 	}
 
-	if _, clusterMigration := sc.Stack.Annotations[forwardBackendAnnotation]; clusterMigration {
-		i := int32(1)
-		result.Spec.MinReplicas = &i
-		result.Spec.MaxReplicas = i
-	}
-
 	return result, nil
 }
 

pkg/core/stack_resources_test.go

@@ -1161,18 +1161,19 @@ func TestStackGenerateService(t *testing.T) {
 
 func TestStackGenerateDeployment(t *testing.T) {
 	for _, tc := range []struct {
-		name               string
-		hpaEnabled         bool
-		stackReplicas      int32
-		minReadySeconds    int32
-		prescalingActive   bool
-		prescalingReplicas int32
-		deploymentReplicas int32
-		noTrafficSince     time.Time
-		expectedReplicas   int32
-		maxUnavailable     int
-		maxSurge           int
-		stackAnnotations   map[string]string
+		name                  string
+		hpaEnabled            bool
+		stackReplicas         int32
+		minReadySeconds       int32
+		prescalingActive      bool
+		prescalingReplicas    int32
+		deploymentReplicas    int32
+		noTrafficSince        time.Time
+		expectedReplicas      int32
+		maxUnavailable        int
+		maxSurge              int
+		stackAnnotations      map[string]string
+		expectedDeploymentNil bool
 	}{
 		{
 			name:               "stack scaled down to zero, deployment still running",
@@ -1310,10 +1311,10 @@ func TestStackGenerateDeployment(t *testing.T) {
 			name:               "cluster migration should scale down deployment",
 			stackReplicas:      3,
 			deploymentReplicas: 3,
-			expectedReplicas:   1,
 			stackAnnotations: map[string]string{
 				forwardBackendAnnotation: "fwd-deployment",
 			},
+			expectedDeploymentNil: true,
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
@@ -1375,6 +1376,10 @@ func TestStackGenerateDeployment(t *testing.T) {
 				}
 			}
 			deployment := c.GenerateDeployment()
+			if tc.expectedDeploymentNil {
+				require.Nil(t, deployment, "Failed to generate nil deployment")
+				return
+			}
 			expected := &apps.Deployment{
 				ObjectMeta: testResourceMeta,
 				Spec: apps.DeploymentSpec{
@@ -1517,9 +1522,7 @@ func TestGenerateHPA(t *testing.T) {
 					},
 				},
 			},
-			expectedBehavior:    exampleBehavior,
-			expectedMinReplicas: &min,
-			expectedMaxReplicas: 1,
+			expectedBehavior: nil,
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {

pkg/core/stackset.go

@@ -83,7 +83,7 @@ func (ssc *StackSetContainer) NewStack() (*StackContainer, string) {
 			spec.RouteGroup = ssc.StackSet.Spec.RouteGroup.DeepCopy()
 		}
 
-		stackAnnotations := make(map[string]string)
+		var stackAnnotations map[string]string
 		if a := ssc.StackSet.Spec.StackTemplate.Annotations; a != nil {
 			stackAnnotations = a
 		}