Helm Chart Testing

Helm Chart Testing

Write effective built-in Helm tests using pod annotations that run with helm test. Focus on designing tests that verify releases work correctly.

Keywords

helm test, helm.sh/hook, test-success, test-failure, pod test, test annotation, smoke test, connectivity test, configuration validation, release verification, failing test, test coverage

When to Use This Skill

• Adding test pods to a Helm chart
• Diagnosing why Helm tests are failing
• Determining what needs testing in a chart
• Writing connectivity, configuration, or readiness tests
• Designing test strategy for complex charts

Related Skills

• helm-chart-development - Chart structure and templating
• helm-chart-maintenance - Testing in CI/CD pipelines
• k8s-platform-operations - Debugging test failures

Quick Reference

How Helm Tests Work

1. Define test pods in templates/ with helm.sh/hook: test annotation
2. Install chart with helm install or helm upgrade
3. Run tests with helm test RELEASE_NAME
4. Helm creates pods, executes them, reports results

Test passes: Pod exits with code 0 Test fails: Pod exits with non-zero code

Test Annotations

Test Analysis: What to Test

Analysis questions:

• What is the minimum viable verification that the release worked?
• What are the critical failure modes?
• What external dependencies exist?
• Can tests run safely in production?

Test Categories

Basic Test Pod Structure

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-test-connectivity"
  annotations:
    helm.sh/hook: test-success
    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
spec:
  containers:
  - name: test
    image: curlimages/curl:8.7.1
    command:
    - sh
    - -c
    - |
      set -e
      curl -f http://myapp-service:8080/health
  restartPolicy: Never

Best practices:

• Use restartPolicy: Never
• Use lightweight images (curlimages/curl, busybox, alpine)
• One test pod tests one thing well
• Exit code 0 = pass, non-zero = fail

Common test images (always pin to a specific tag, not latest):

• curlimages/curl:8.7.1 - HTTP endpoint checks
• busybox:1.36 - Basic shell utilities
• bitnami/kubectl:1.29 - Kubernetes API queries
• postgres:16-alpine, mysql:8.0-oracle - Database connectivity

Test Examples

Service Connectivity Test

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-api-test"
  annotations:
    helm.sh/hook: test-success
    helm.sh/hook-delete-policy: before-hook-creation,hook-succeeded
spec:
  containers:
  - name: api-test
    image: curlimages/curl:8.7.1
    command:
    - sh
    - -c
    - |
      set -e
      # Test main endpoint
      curl -f http://{{ .Release.Name }}-service:8080/health || exit 1
      # Verify response content
      curl -s http://{{ .Release.Name }}-service:8080/health | grep -q "status.*ok" || exit 1
      {{- if .Values.auth.enabled }}
      # Test authenticated endpoint
      curl -f http://{{ .Release.Name }}-service:8080/secure \
        -H "Authorization: Bearer {{ .Values.auth.testToken }}" || exit 1
      {{- end }}
  restartPolicy: Never

Configuration Validation Test

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-config-test"
  annotations:
    helm.sh/hook: test-success
spec:
  containers:
  - name: config-test
    image: busybox:1.36
    command:
    - sh
    - -c
    - |
      set -e
      test -f /app/config.yaml || exit 1
      grep -q "logLevel: {{ .Values.logLevel }}" /app/config.yaml || exit 1
      grep -q "database:" /app/config.yaml || exit 1
  volumeMounts:
  - name: config
    mountPath: /app/config.yaml
    subPath: config.yaml
  volumes:
  - name: config
    configMap:
      name: {{ include "myapp.fullname" . }}-config
  restartPolicy: Never

Deployment Readiness Test

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-readiness-test"
  annotations:
    helm.sh/hook: test-success
spec:
  serviceAccountName: {{ include "myapp.fullname" . }}-test-sa
  containers:
  - name: kubectl-test
    image: bitnami/kubectl:1.29
    command:
    - sh
    - -c
    - |
      set -e
      kubectl get deployment {{ .Release.Name }} -n {{ .Release.Namespace }} -o json | \
        jq -e '.status.readyReplicas == {{ .Values.replicaCount }}' || exit 1
  restartPolicy: Never

Database Connection Test

apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-db-test"
  annotations:
    helm.sh/hook: test-success
spec:
  containers:
  - name: db-test
    image: postgres:16-alpine
    command:
    - sh
    - -c
    - |
      set -e
      nc -zv {{ .Values.database.host }} {{ .Values.database.port }} || exit 1
      PGPASSWORD={{ .Values.database.password }} \
      psql -h {{ .Values.database.host }} -p {{ .Values.database.port }} \
            -U {{ .Values.database.user }} -d {{ .Values.database.name }} \
            -c "SELECT 1;" || exit 1
  restartPolicy: Never

Test Design Considerations

Test Independence

Each test should verify one thing well:

# Good: Single focused test
metadata:
  name: "{{ .Release.Name }}-test-health"

# Avoid: Tests multiple unrelated things
metadata:
  name: "{{ .Release.Name }}-test-everything"

Resource Management

Set limits to prevent exhaustion:

spec:
  containers:
  - name: test
    image: curlimages/curl:8.7.1
    resources:
      requests:
        cpu: 100m
        memory: 64Mi
      limits:
        cpu: 200m
        memory: 128Mi

Cleanup Policies

For debugging:

metadata:
  annotations:
    helm.sh/hook-delete-policy: never

Error Handling

Provide clear failure messages:

command:
- sh
- -c
- |
  set -e
  if ! curl -f http://service:8080/health; then
    echo "ERROR: Service health check failed"
    echo "Troubleshooting: kubectl get svc, kubectl logs -l app=myapp"
    exit 1
  fi

Security

Use least privilege RBAC:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: {{ include "myapp.fullname" . }}-test-sa
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: {{ include "myapp.fullname" . }}-test-role
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: {{ include "myapp.fullname" . }}-test-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: {{ include "myapp.fullname" . }}-test-role
subjects:
- kind: ServiceAccount
  name: {{ include "myapp.fullname" . }}-test-sa

Don't embed secrets:

# Avoid
command: ["curl", "-H", "Authorization: Bearer super-secret-key", "http://service/"]

# Better
env:
- name: TEST_TOKEN
  valueFrom:
    secretKeyRef:
      name: test-credentials
      key: token

Organizing Tests

mychart/
├── templates/
│   ├── tests/
│   │   ├── test-service-connectivity.yaml
│   │   ├── test-config-validation.yaml
│   │   └── test-readiness.yaml
│   ├── deployment.yaml
│   └── service.yaml

Conditional Testing

Enable/disable tests globally:

{{- if .Values.tests.enabled }}
apiVersion: v1
kind: Pod
metadata:
  name: "{{ .Release.Name }}-test"
  annotations:
    helm.sh/hook: test-success
spec:
  # ...
{{- end }}

In values.yaml:

tests:
  enabled: true

Test specific configurations:

{{- if .Values.metrics.enabled }}
# metrics test
{{- end }}

Test Execution Order

Use helm.sh/hook-weight (lower runs first):

# Test 1: Run first
metadata:
  annotations:
    helm.sh/hook-weight: "-5"

---
# Test 2: Run second
metadata:
  annotations:
    helm.sh/hook-weight: "0"

Running and Debugging

Running Tests

helm test my-release
helm test my-release --logs
helm test my-release --timeout 10m
helm test my-release -n my-namespace

Debugging Failed Tests

kubectl get pods -n namespace -l helm.sh/hook=test
kubectl logs my-release-test-connectivity -n namespace
kubectl describe pod my-release-test-connectivity -n namespace

Common Test Failures

Anti-Patterns

Don't Test During Installation

# Wrong - runs during install
helm.sh/hook: post-install

# Correct - runs with helm test
helm.sh/hook: test-success

Don't Over-Test Platform Guarantees

# Wrong - Kubernetes guarantees this
command: ["kubectl", "get", "pod", "|", "grep", "myapp"]

# Correct - test application functionality
command: ["curl", "http://myapp-service/health"]

Avoid Fragile Tests

# Fragile - exact match
response=$(curl http://service/health)
[ "$response" == '{"status":"ok"}' ]

# Robust - content check
curl http://service/health | grep -q "status.*ok"

Avoid Long-Running Tests

# Avoid - waits 60 seconds
for i in $(seq 1 60); do sleep 1; done

# Prefer - quick check
curl -f --max-time 10 http://service/health