Hooks and Chart Tests

Doing work before or after the main install

Hooks are ordinary templates with a helm.sh/hook annotation that Helm runs at specific points rather than as part of the main resources: pre-install, post-install, pre-upgrade, post-upgrade, pre-delete, post-delete, pre-rollback, post-rollback and test. A typical use is a database migration Job as a pre-upgrade hook. Helm waits for hook Jobs to complete; if a hook fails, the release operation fails. helm.sh/hook-weight orders hooks (lower first), and helm.sh/hook-delete-policy controls cleanup: before-hook-creation (the default: delete the previous hook object before creating a new one), hook-succeeded and hook-failed. Hook resources are not managed as part of the release, so they are not removed by helm uninstall unless a delete policy does it. Chart tests are pods annotated helm.sh/hook: test, run on demand by helm test RELEASE, for example to call the service's health endpoint.

A migration Job as a pre-upgrade hook

Runs before new pods roll out; deleted once it succeeds.

apiVersion: batch/v1
kind: Job
metadata:
  name: {{ include "shop-api.fullname" . }}-migrate
  annotations:
    "helm.sh/hook": pre-install,pre-upgrade
    "helm.sh/hook-weight": "0"
    "helm.sh/hook-delete-policy": before-hook-creation,hook-succeeded
spec:
  backoffLimit: 1
  template:
    spec:
      restartPolicy: Never
      containers:
        - name: migrate
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          command: ["./manage", "migrate", "--no-input"]
          envFrom:
            - secretRef:
                name: shop-db-credentials

Prep before the kitchen opens

Pre-upgrade hooks are the morning prep before the restaurant opens: chop vegetables and update the menu board first, then let customers in. If the prep fails, the doors stay shut.

Quick check: Which annotation makes a pod run only when you execute `helm test`?

• helm.sh/hook: post-install
• helm.sh/hook-weight: test
• helm.sh/resource-policy: keep
• helm.sh/hook: test