Helm Charts

Package and deploy Kubernetes applications using Helm, the package manager for Kubernetes.

When to Use This Skill

Use this skill when:

• Creating reusable Kubernetes application packages

• Deploying applications with configurable values

• Managing Helm releases and upgrades

• Using third-party Helm charts

• Implementing chart versioning and repositories

Prerequisites

• Helm 3.x installed

• kubectl configured with cluster access

• Basic Kubernetes knowledge

Chart Structure

mychart/ ├── Chart.yaml # Chart metadata ├── values.yaml # Default configuration values ├── charts/ # Chart dependencies ├── templates/ # Kubernetes manifest templates │ ├── deployment.yaml │ ├── service.yaml │ ├── ingress.yaml │ ├── configmap.yaml │ ├── secret.yaml │ ├── _helpers.tpl # Template helpers │ ├── NOTES.txt # Post-install notes │ └── tests/ │ └── test-connection.yaml └── .helmignore # Files to ignore

Chart.yaml

apiVersion: v2 name: myapp description: A Helm chart for MyApp type: application version: 1.0.0 appVersion: "2.0.0" keywords:

• myapp
• web maintainers:
• name: DevOps Team email: devops@example.com dependencies:
• name: postgresql version: "12.x.x" repository: "https://charts.bitnami.com/bitnami" condition: postgresql.enabled

values.yaml

replicaCount: 2

image: repository: myapp tag: "" # Defaults to appVersion pullPolicy: IfNotPresent

service: type: ClusterIP port: 80

ingress: enabled: false className: nginx hosts: - host: myapp.example.com paths: - path: / pathType: Prefix tls: []

resources: limits: cpu: 500m memory: 256Mi requests: cpu: 100m memory: 128Mi

postgresql: enabled: true auth: database: myapp

Templates

Deployment Template

templates/deployment.yaml

apiVersion: apps/v1 kind: Deployment metadata: name: {{ include "myapp.fullname" . }} labels: {{- include "myapp.labels" . | nindent 4 }} spec: replicas: {{ .Values.replicaCount }} selector: matchLabels: {{- include "myapp.selectorLabels" . | nindent 6 }} template: metadata: labels: {{- include "myapp.selectorLabels" . | nindent 8 }} spec: containers: - name: {{ .Chart.Name }} image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}" imagePullPolicy: {{ .Values.image.pullPolicy }} ports: - name: http containerPort: 8080 {{- with .Values.resources }} resources: {{- toYaml . | nindent 12 }} {{- end }} env: - name: DATABASE_URL valueFrom: secretKeyRef: name: {{ include "myapp.fullname" . }}-secrets key: database-url

Helper Functions

templates/_helpers.tpl

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

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

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

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

Conditional Resources

templates/ingress.yaml

{{- if .Values.ingress.enabled -}} apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: {{ include "myapp.fullname" . }} labels: {{- include "myapp.labels" . | nindent 4 }} {{- with .Values.ingress.annotations }} annotations: {{- toYaml . | nindent 4 }} {{- end }} spec: ingressClassName: {{ .Values.ingress.className }} {{- if .Values.ingress.tls }} tls: {{- range .Values.ingress.tls }} - hosts: {{- range .hosts }} - {{ . | quote }} {{- end }} secretName: {{ .secretName }} {{- end }} {{- end }} rules: {{- range .Values.ingress.hosts }} - host: {{ .host | quote }} http: paths: {{- range .paths }} - path: {{ .path }} pathType: {{ .pathType }} backend: service: name: {{ include "myapp.fullname" $ }} port: number: {{ $.Values.service.port }} {{- end }} {{- end }} {{- end }}

Helm Commands

Installing Charts

Install from local chart

helm install myapp ./mychart

Install with custom values

helm install myapp ./mychart -f custom-values.yaml

Install with value overrides

helm install myapp ./mychart
--set replicaCount=3
--set image.tag=2.0.0

Install in specific namespace

helm install myapp ./mychart -n production --create-namespace

Dry run to preview

helm install myapp ./mychart --dry-run --debug

Managing Releases

List releases

helm list helm list -A # All namespaces

Upgrade release

helm upgrade myapp ./mychart helm upgrade myapp ./mychart -f new-values.yaml

Rollback

helm rollback myapp 1 helm history myapp

Uninstall

helm uninstall myapp

Chart Development

Create new chart

helm create mychart

Lint chart

helm lint ./mychart

Template locally (debug)

helm template myapp ./mychart

Package chart

helm package ./mychart

Update dependencies

helm dependency update ./mychart

Repositories

Add repository

helm repo add bitnami https://charts.bitnami.com/bitnami

Update repositories

helm repo update

Search charts

helm search repo postgresql helm search hub prometheus

Install from repo

helm install postgres bitnami/postgresql

Show chart info

helm show values bitnami/postgresql

Advanced Features

Hooks

templates/pre-install-job.yaml

apiVersion: batch/v1 kind: Job metadata: name: {{ include "myapp.fullname" . }}-migration annotations: "helm.sh/hook": pre-install,pre-upgrade "helm.sh/hook-weight": "-5" "helm.sh/hook-delete-policy": hook-succeeded spec: template: spec: containers: - name: migrate image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}" command: ["./migrate.sh"] restartPolicy: Never

Tests

templates/tests/test-connection.yaml

apiVersion: v1 kind: Pod metadata: name: "{{ include "myapp.fullname" . }}-test-connection" annotations: "helm.sh/hook": test spec: containers: - name: wget image: busybox command: ['wget'] args: ['{{ include "myapp.fullname" . }}:{{ .Values.service.port }}'] restartPolicy: Never

Run tests

helm test myapp

Library Charts

Chart.yaml

apiVersion: v2 name: mylib type: library version: 1.0.0

Using library chart

dependencies:

• name: mylib version: "1.x.x" repository: "file://../mylib"

OCI Registry Support

Login to registry

helm registry login registry.example.com

Push chart to OCI registry

helm push mychart-1.0.0.tgz oci://registry.example.com/charts

Pull from OCI registry

helm pull oci://registry.example.com/charts/mychart --version 1.0.0

Install from OCI

helm install myapp oci://registry.example.com/charts/mychart

Common Issues

Issue: YAML Indentation Errors

Problem: Template renders with wrong indentation Solution: Use nindent helper function

{{- toYaml .Values.resources | nindent 12 }}

Issue: Values Not Applying

Problem: Custom values not reflected Solution: Check value paths, use --debug flag

helm template myapp ./mychart --debug

Issue: Dependency Errors

Problem: Chart dependencies not found Solution: Run helm dependency update

Issue: Release Already Exists

Problem: Cannot install, release exists Solution: Use helm upgrade --install

helm upgrade --install myapp ./mychart

Best Practices

• Use semantic versioning for charts

• Provide comprehensive default values

• Document all values in values.yaml with comments

• Use helper templates for repeated patterns

• Implement chart tests

• Use .helmignore to exclude unnecessary files

• Pin dependency versions

• Use helm lint in CI pipelines

Related Skills

• kubernetes-ops - K8s fundamentals

• argocd-gitops - GitOps with Helm

• kustomize - Alternative templating