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

code

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

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

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

yaml

# 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

yaml

# 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

yaml

# 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

bash

# 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

bash

# 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

bash

# 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

bash

# 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

yaml

# 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

yaml

# 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

bash

# Run tests
helm test myapp

Library Charts

yaml

# Chart.yaml
apiVersion: v2
name: mylib
type: library
version: 1.0.0

yaml

# Using library chart
dependencies:
  - name: mylib
    version: "1.x.x"
    repository: "file://../mylib"

OCI Registry Support

bash

# 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

yaml

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

Issue: Values Not Applying

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

bash

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

bash

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