Use Helm hook to add labels to a namespace before chart installation

label-ns.yaml

# This hook depends on helm creating the target namespace if it doesn't exist
# before the hook is called. This is the case on Helm v2.9.1
apiVersion: batch/v1
kind: Job
metadata:
  name: label-ns
  namespace: cicd
  labels:
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }}
  annotations:
    helm.sh/hook: pre-install
    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
spec:
  template:
    spec:
      containers:
      - name: labeler
        image: bitnami/kubectl:1.20.10
        command:
        - /bin/sh
        - -ec
        - |
          kubectl label --overwrite namespace {{ .Release.Namespace }} elbv2.k8s.aws/pod-readiness-gate-inject=enabled
      restartPolicy: OnFailure
      # use circleci-user service account setup on cicd namespace for permissions to change namespaces
      serviceAccountName: circleci-user