[Labels] Argo-rollout's experiments and replicaSet cannot be enriched with custom labels

[ayureidini]

Summary

I have noticed that there is no mechanism to add custom labels to Experiments and their associated ReplicaSets.

What change needs making?
I have tested this change for canary strategy and the idea would be to propagate labels from spec.template.labels into Experiments and ReplicaSets upon creation.

• https://github.com/argoproj/argo-rollouts/blob/master/experiments/replicaset.go#L76
• https://github.com/argoproj/argo-rollouts/blob/master/rollout/experiment.go#L24

diff --git a/experiments/replicaset.go b/experiments/replicaset.go
index d91843a0..56424ac9 100644
--- a/experiments/replicaset.go
+++ b/experiments/replicaset.go
@@ -166,17 +166,21 @@ func newReplicaSetFromTemplate(experiment *v1alpha1.Experiment, template v1alpha
        newRSTemplate.Labels = labelsutil.CloneAndAddLabel(newRSTemplate.Labels, v1alpha1.DefaultRolloutUniqueLabelKey, podHash)
        // Add podTemplateHash label to selector.
        newRSSelector := labelsutil.CloneSelectorAndAddLabel(template.Selector, v1alpha1.DefaultRolloutUniqueLabelKey, podHash)
+       newRSLabels := map[string]string{}
+       // enrich with template labels
+       for k, v := range newRSTemplate.Labels {
+               newRSLabels[k] = v
+       }
+       newRSLabels[v1alpha1.DefaultRolloutUniqueLabelKey] = podHash
 
        // The annotations must be different for each template because annotations are used to match
        // replicasets to templates. We inject the experiment and template name in the replicaset
        // annotations to ensure uniqueness.
        rs := appsv1.ReplicaSet{
                ObjectMeta: metav1.ObjectMeta{
-                       Name:      fmt.Sprintf("%s-%s", experiment.Name, template.Name),
-                       Namespace: experiment.Namespace,
-                       Labels: map[string]string{
-                               v1alpha1.DefaultRolloutUniqueLabelKey: podHash,
-                       },
+                       Name:            fmt.Sprintf("%s-%s", experiment.Name, template.Name),
+                       Namespace:       experiment.Namespace,
+                       Labels:          newRSLabels,
                        OwnerReferences: []metav1.OwnerReference{*metav1.NewControllerRef(experiment, controllerKind)},
                        Annotations:     replicaSetAnnotations,
                },
diff --git a/rollout/experiment.go b/rollout/experiment.go
index 7b28cc28..c65e7322 100644
--- a/rollout/experiment.go
+++ b/rollout/experiment.go
@@ -35,14 +35,19 @@ func GetExperimentFromTemplate(r *v1alpha1.Rollout, stableRS, newRS *appsv1.Repl
        if r.Annotations != nil {
                revision = r.Annotations[annotations.RevisionAnnotation]
        }
+       newExperimentabels := map[string]string{}
+       // enrich with template labels
+       for k, v := range r.Labels {
+               newExperimentabels[k] = v
+       }
+       newExperimentabels[v1alpha1.DefaultRolloutUniqueLabelKey] = podHash
+
        experiment := &v1alpha1.Experiment{
                ObjectMeta: metav1.ObjectMeta{
                        Name:            fmt.Sprintf("%s-%s-%s-%d", r.Name, podHash, revision, currentStep),
                        Namespace:       r.Namespace,
                        OwnerReferences: []metav1.OwnerReference{*metav1.NewControllerRef(r, controllerKind)},
-                       Labels: map[string]string{
-                               v1alpha1.DefaultRolloutUniqueLabelKey: podHash,
-                       },
+                       Labels:          newExperimentabels,
                        Annotations: map[string]string{
                                annotations.RevisionAnnotation: revision,
                        },

Use Cases

This can be useful for complying to Tagging Policy imposed at cluster level. Indeed, this can be useful for enabling automatic reporting but also give required information for investigation. This can be levered by using Open Policy Agent (OPA) Gatekeeper.

---

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[OpenGuidou]

It looks indeed like a miss. Would you mind raising a PR to add it ?

[ayureidini]

@OpenGuidou : Pull-request submitted: #4118

[ayureidini]

Pull-request was merged, so I am closing this ticket.