fix: Rollback change on service creation with weightless experiments (#…

…2624)

BREAKING CHANGE There was an unintentional change in behavior related to service creation with experiments introduced in v1.4.0 this has been reverted in v1.4.1 back to the original behavior. In v1.4.0 services where always created with for inline experiments even if there was no weight set. In 1.4.1 we go back to the original behavior of requiring weight to be set in order to create a service.

docs/features/experiment.md

@@ -6,7 +6,7 @@ The Experiment CRD allows users to have ephemeral runs of one or more ReplicaSet
 running ephemeral ReplicaSets, the Experiment CRD can launch AnalysisRuns alongside the ReplicaSets.
 Generally, those AnalysisRun is used to confirm that new ReplicaSets are running as expected.
 
-A Service routing traffic to the Experiment ReplicaSet is also generated.
+A Service routing traffic to the Experiment ReplicaSet is also generated if a weight for that experiment is set.
 
 ## Use cases of Experiments
 
@@ -245,7 +245,7 @@ to `experiment-baseline`, leaving the remaining 90% of traffic to the old stack.
 
 !!! note
     When a weighted experiment step with traffic routing is used, a
-    Service is auto-created for each experiment template. The traffic routers use
+    service is auto-created for each experiment template. The traffic routers use
     this service to send traffic to the experiment pods.
 
 By default, the generated Service has the name of the ReplicaSet and inherits

rollout/experiment.go

@@ -64,7 +64,9 @@ func GetExperimentFromTemplate(r *v1alpha1.Rollout, stableRS, newRS *appsv1.Repl
 			Name:     templateStep.Name,
 			Replicas: templateStep.Replicas,
 		}
-		template.Service = &v1alpha1.TemplateService{}
+		if templateStep.Weight != nil {
+			template.Service = &v1alpha1.TemplateService{}
+		}
 		templateRS := &appsv1.ReplicaSet{}
 		switch templateStep.SpecRef {
 		case v1alpha1.CanarySpecRef:

rollout/experiment_test.go

@@ -791,7 +791,7 @@ func TestRolloutCreateExperimentWithService(t *testing.T) {
 					Replicas: pointer.Int32Ptr(1),
 					Weight:   pointer.Int32Ptr(5),
 				},
-				// Service should also be created for "canary-template"
+				// Service should NOT be created for "canary-template"
 				{
 					Name:     "canary-template",
 					SpecRef:  v1alpha1.CanarySpecRef,
@@ -818,5 +818,5 @@ func TestRolloutCreateExperimentWithService(t *testing.T) {
 	assert.NotNil(t, ex.Spec.Templates[0].Service)
 
 	assert.Equal(t, "canary-template", ex.Spec.Templates[1].Name)
-	assert.NotNil(t, ex.Spec.Templates[1].Service)
+	assert.Nil(t, ex.Spec.Templates[1].Service)
 }