kapp injects label in Service Selector but not StatefulSet Pod Template

[frimik]

Service has its selector modified by kapp:

apiVersion: v1
kind: Service
spec:
  selector:
    app.kubernetes.io/component: prometheus
    app.kubernetes.io/instance: k8s
    app.kubernetes.io/name: prometheus
    app.kubernetes.io/part-of: kube-prometheus
    kapp.k14s.io/app: "1684079013099136212"

Leading to the Service not having any matching Pods.

Whereas StatefulSet does not have its spec.template.metadata.labels modified:

spec:
  template:
    metadata:
      labels:
        app.kubernetes.io/component: prometheus
        app.kubernetes.io/instance: k8s
        app.kubernetes.io/managed-by: prometheus-operator
        app.kubernetes.io/name: prometheus
        app.kubernetes.io/part-of: kube-prometheus
        app.kubernetes.io/version: 2.43.0
        operator.prometheus.io/name: k8s
        operator.prometheus.io/shard: "0"
        prometheus: k8s

Why is the selector modified at all?

What steps did you take:

• Define a Service
• Define a StatefulSet
• Define selectors in Service to match the Labels in the StatefulSet Pod Template.
• Deploy these two via kapp.

What happened:

• kapp adds label to the Service
• kapp adds label to the Service selector
• kapp adds label to the StatefulSet.
• kapp does NOT add labels to the StatefulSet Pod Template.

What did you expect:

One of:

• label to not be added in Service selector
• label to be added in Pod Template

Anything else you would like to add:

I would expect kapp to "just work" for passing something this simple throuigh it.

Environment:

• kapp version (use kapp --version): kapp version 0.54.3
• OS (e.g. from /etc/os-release): Ubuntu 22.04.1 LTS
• Kubernetes version (use kubectl version) v1.22.17

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[praveenrewar]

Hi @frimik!
kapp has some default labelScopingRules and ownershipRules to inject it's labels into resources. By default, kapp should inject the labels into the spec.template.metadata.labels of a statefulset (

kapp/pkg/kapp/config/default.go

Line 272 in 3e2edfa

- apiVersionKindMatcher: {apiVersion: apps/v1, kind: StatefulSet}

), unless you have the kapp.k14s.io/disable-default-ownership-label-rules annotation present (if this is not the case, could you share your StatefulSet yaml?). I tried creating a StatefulSet and I could see the labels under spec.template.metadata.labels.