Helm Chart Development

Comprehensive guidance for creating, testing, and packaging custom Helm charts with best practices for maintainability and reusability.

When to Use

Use this skill automatically when:

User wants to create a new Helm chart
User needs to validate chart structure or templates
User mentions testing charts locally
User wants to package or publish charts
User needs to manage chart dependencies
User asks about chart best practices

Chart Creation & Structure

Create New Chart

Scaffold new chart with standard structure

helm create mychart

Creates:

mychart/

├── Chart.yaml # Chart metadata

├── values.yaml # Default values

├── charts/ # Chart dependencies

├── templates/ # Kubernetes manifests

│ ├── NOTES.txt # Post-install instructions

│ ├── _helpers.tpl # Template helpers

│ ├── deployment.yaml

│ ├── service.yaml

│ ├── ingress.yaml

│ └── tests/

│ └── test-connection.yaml

└── .helmignore # Files to ignore

Chart.yaml Structure

Chart.yaml - Chart metadata

apiVersion: v2 # Helm 3 uses v2 name: mychart # Chart name version: 0.1.0 # Chart version (SemVer) appVersion: "1.0.0" # Application version description: A Helm chart for Kubernetes type: application # application or library keywords:

api
web home: https://example.com sources:
https://github.com/example/mychart maintainers:
name: John Doe email: john@example.com dependencies: # Chart dependencies
name: postgresql version: "12.1.9" repository: https://charts.bitnami.com/bitnami condition: postgresql.enabled # Optional: enable/disable tags: # Optional: group dependencies
- database

Chart Validation & Testing

Lint Chart

Basic linting

helm lint ./mychart

Strict linting (warnings as errors)

helm lint ./mychart --strict

Lint with specific values

helm lint ./mychart --values values.yaml --strict

Lint with multiple value files

helm lint ./mychart
--values values/common.yaml
--values values/production.yaml
--strict

Render Templates Locally

Render all templates

helm template mychart ./mychart

Render with custom release name and namespace

helm template myrelease ./mychart --namespace production

Render with values

helm template myrelease ./mychart --values values.yaml

Render specific template

helm template myrelease ./mychart
--show-only templates/deployment.yaml

Validate against Kubernetes API

helm template myrelease ./mychart --validate

Dry-Run Installation

Dry-run with server-side validation

helm install myrelease ./mychart
--namespace production
--dry-run
--debug

Run Chart Tests

Install chart, run tests, cleanup

helm install myrelease ./mychart --namespace test helm test myrelease --namespace test --logs helm uninstall myrelease --namespace test

Chart Test Structure:

templates/tests/test-connection.yaml

apiVersion: v1 kind: Pod metadata: name: "{{ include "mychart.fullname" . }}-test-connection" annotations: "helm.sh/hook": test "helm.sh/hook-delete-policy": hook-succeeded,hook-failed spec: containers:

name: wget image: busybox command: ['wget'] args: ['{{ include "mychart.fullname" . }}:{{ .Values.service.port }}'] restartPolicy: Never

Template Development

Template Helpers (_helpers.tpl)

{{/* Expand the name of the chart. */}} {{- define "mychart.name" -}} {{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }} {{- end }}

{{/* Create a fully qualified app name. */}} {{- define "mychart.fullname" -}} {{- if .Values.fullnameOverride }} {{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }} {{- else }} {{- $name := default .Chart.Name .Values.nameOverride }} {{- if contains $name .Release.Name }} {{- .Release.Name | trunc 63 | trimSuffix "-" }} {{- else }} {{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }} {{- end }} {{- end }} {{- end }}

{{/* Common labels */}} {{- define "mychart.labels" -}} helm.sh/chart: {{ include "mychart.chart" . }} {{ include "mychart.selectorLabels" . }} {{- if .Chart.AppVersion }} app.kubernetes.io/version: {{ .Chart.AppVersion | quote }} {{- end }} app.kubernetes.io/managed-by: {{ .Release.Service }} {{- end }}

{{/* Selector labels */}} {{- define "mychart.selectorLabels" -}} app.kubernetes.io/name: {{ include "mychart.name" . }} app.kubernetes.io/instance: {{ .Release.Name }} {{- end }}

Chart Dependencies

Define Dependencies (Chart.yaml)

Chart.yaml

dependencies:

name: postgresql version: "12.1.9" repository: https://charts.bitnami.com/bitnami condition: postgresql.enabled
name: redis version: "17.0.0" repository: https://charts.bitnami.com/bitnami condition: redis.enabled
name: common # Local dependency version: "1.0.0" repository: file://../common-library

Manage Dependencies

Download/update dependencies

helm dependency update ./mychart

Build from existing Chart.lock

helm dependency build ./mychart

List dependencies

helm dependency list ./mychart

Configure Subchart Values

values.yaml - Parent chart

postgresql: enabled: true auth: username: myapp database: myapp existingSecret: myapp-db-secret primary: persistence: size: 10Gi

redis: enabled: true auth: enabled: false master: persistence: size: 5Gi

Chart Packaging & Distribution

Package Chart

Package chart into .tgz

helm package ./mychart

Package with specific destination

helm package ./mychart --destination ./dist/

Package and update dependencies

helm package ./mychart --dependency-update

Sign package (requires GPG key)

helm package ./mychart --sign --key mykey --keyring ~/.gnupg/secring.gpg

Chart Repository

Create repository index

helm repo index ./repo/

Push to OCI registry (Helm 3.8+)

helm push mychart-0.1.0.tgz oci://registry.example.com/charts

For detailed examples of values.yaml design, schema validation, chart documentation templates, testing workflows, common chart patterns, and best practices, see REFERENCE.md.

Agentic Optimizations

Context Command

Lint (strict) helm lint ./mychart --strict

Render specific template helm template myapp ./mychart --show-only templates/deployment.yaml

Dry-run validation helm install myapp ./mychart --dry-run --debug 2>&1 | head -100

Package chart helm package ./mychart --dependency-update

Related Skills

Helm Release Management - Using charts to deploy
Helm Debugging - Troubleshooting chart issues
Helm Values Management - Configuring charts

References

Helm Chart Development Guide
Helm Best Practices
Helm Template Guide
Chart Testing