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Chart Tests

A chart contains a number of Kubernetes resources and components that work together. As a chart author, you may want to write some tests that validate that your charts works as expected when it is installed. These tests also help the chart consumer understand what your chart is supposed to do.

A test in a helm chart lives under the templates/ directory and is a pod definition that specifies a container with a given command to run. The container should exit successfully (exit 0) for a test to be considered a success. The pod definiton must contain one of the helm test hook annotations: helm.sh/hooks: test-success or helm.sh/hooks: test-failure.

Example tests:

  • Validate that your configuration from the values.yaml file was properly injected.
    • Make sure your username and password work correctly
    • Make sure an incorrect username and password does not work
  • Assert that your services are up and correctly load balancing
  • etc.

You can run the pre-defined tests in Helm on a release using the command helm test <RELEASE_NAME>. For a chart consumer, this is a great way to sanity check that their release of a chart (or application) works as expected.

A Breakdown of the Helm Test Hooks

In Helm, there are two test hooks: test-success and test-failure

test-success indiciates that test pod should complete successfully. In other words, the containers in the pod should exit 0. test-failure is a way to assert that a test pod should not complete successfully. If the containers in the pod do not exit 0, that indiciates success.

Example Test

Here is an example of a helm test pod definition in an example maraidb chart:

mariadb/
  Chart.yaml
  LICENSE
  README.md
  values.yaml
  charts/
  templates/
  templates/mariadb-tests.yaml

In wordpress/templates/mariadb-tests.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: "{{.Release.Name}}-credentials-test"
  annotations:
    "helm.sh/hook": test-success
spec:
  containers:
    - name: {{.Release.Name}}-credentials-test
      image: bitnami/mariadb:{{.Values.imageTag}}
      command: ["mysql",  "--host={{.Release.Name}}-mariadb", "--user={{.Values.mariadbUser}}", "--password={{.Values.mariadbPassword}}"]
  restartPolicy: Never

Steps to Run a Test Suite on a Release

  1. $ helm install mariadb
NAME:   quirky-walrus
LAST DEPLOYED: Mon Feb 13 13:50:43 2017
NAMESPACE: default
STATUS: DEPLOYED
  1. $ helm test quirky-walrus
RUNNING: quirky-walrus-credentials-test
SUCCESS: quirky-walrus-credentials-test

Notes

  • You can define as many tests as you would like in a single yaml file or spread across several yaml files in the templates/ directory
  • You are welcome to nest your test suite under a tests/ directory like <chart-name>/templates/tests/ for more isolation