Kubernetes Helm Charts: Package and Deploy Applications

What is Helm?

Helm is the package manager for Kubernetes. It simplifies deploying and managing applications by packaging Kubernetes resources into reusable charts.

Why Helm?

Without Helm	With Helm
Many YAML files	Single chart
Manual updates	Versioned releases
Copy/paste configs	Parameterized templates
Hard to rollback	Easy rollbacks

Installation

# macOS
brew install helm

# Linux
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Verify
helm version

Helm Basics

Add Repository

# Add official stable repo
helm repo add bitnami https://charts.bitnami.com/bitnami

# Update repos
helm repo update

# Search charts
helm search repo nginx
helm search hub wordpress

Install Charts

# Install nginx
helm install my-nginx bitnami/nginx

# Install with custom values
helm install my-nginx bitnami/nginx \
    --set replicaCount=3 \
    --set service.type=LoadBalancer

# Install from values file
helm install my-nginx bitnami/nginx -f values.yaml

# Install in namespace
helm install my-nginx bitnami/nginx -n production --create-namespace

Manage Releases

# List releases
helm list
helm list --all-namespaces

# Get release info
helm status my-nginx
helm get values my-nginx
helm get manifest my-nginx

# Upgrade release
helm upgrade my-nginx bitnami/nginx --set replicaCount=5

# Rollback
helm rollback my-nginx 1

# Uninstall
helm uninstall my-nginx

Creating Charts

Chart Structure

my-chart/
├── Chart.yaml          # Chart metadata
├── values.yaml         # Default values
├── charts/             # Dependencies
├── templates/          # Kubernetes manifests
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── _helpers.tpl    # Template helpers
│   └── NOTES.txt       # Post-install notes
└── .helmignore

Chart.yaml

apiVersion: v2
name: my-app
description: A Helm chart for my application
type: application
version: 1.0.0
appVersion: "2.0.0"

keywords:
  - app
  - web

maintainers:
  - name: John Doe
    email: john@example.com

dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled

values.yaml

# Default values
replicaCount: 2

image:
  repository: myapp
  tag: latest
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  className: nginx
  hosts:
    - host: myapp.local
      paths:
        - path: /
          pathType: Prefix

resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 100m
    memory: 128Mi

autoscaling:
  enabled: false
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

postgresql:
  enabled: true
  auth:
    database: myapp
    username: myuser

env:
  - name: NODE_ENV
    value: production

Templates

Deployment Template

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "my-app.fullname" . }}
  labels:
    {{- include "my-app.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  selector:
    matchLabels:
      {{- include "my-app.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      labels:
        {{- include "my-app.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: {{ .Values.service.port }}
              protocol: TCP
          {{- if .Values.env }}
          env:
            {{- toYaml .Values.env | nindent 12 }}
          {{- end }}
          {{- with .Values.resources }}
          resources:
            {{- toYaml . | nindent 12 }}
          {{- end }}
          livenessProbe:
            httpGet:
              path: /health
              port: http
            initialDelaySeconds: 30
          readinessProbe:
            httpGet:
              path: /ready
              port: http
            initialDelaySeconds: 5

Service Template

# templates/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: {{ include "my-app.fullname" . }}
  labels:
    {{- include "my-app.labels" . | nindent 4 }}
spec:
  type: {{ .Values.service.type }}
  ports:
    - port: {{ .Values.service.port }}
      targetPort: http
      protocol: TCP
      name: http
  selector:
    {{- include "my-app.selectorLabels" . | nindent 4 }}

Ingress Template

# templates/ingress.yaml
{{- if .Values.ingress.enabled -}}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ include "my-app.fullname" . }}
  labels:
    {{- include "my-app.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 "my-app.fullname" $ }}
                port:
                  number: {{ $.Values.service.port }}
          {{- end }}
    {{- end }}
{{- end }}

Helper Templates

# templates/_helpers.tpl
{{/*
Expand the name of the chart.
*/}}
{{- define "my-app.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}

{{/*
Create a default fully qualified app name.
*/}}
{{- define "my-app.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 "my-app.labels" -}}
helm.sh/chart: {{ include "my-app.chart" . }}
{{ include "my-app.selectorLabels" . }}
app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}

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

ConfigMap Template

# templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "my-app.fullname" . }}-config
  labels:
    {{- include "my-app.labels" . | nindent 4 }}
data:
  {{- range $key, $value := .Values.config }}
  {{ $key }}: {{ $value | quote }}
  {{- end }}

Template Functions

Common Functions

# String functions
{{ .Values.name | upper }}
{{ .Values.name | lower }}
{{ .Values.name | title }}
{{ .Values.name | quote }}
{{ .Values.name | trunc 63 }}
{{ .Values.name | trimSuffix "-" }}

# Default values
{{ .Values.name | default "myapp" }}

# Conditionals
{{- if .Values.enabled }}
enabled: true
{{- end }}

{{- if and .Values.a .Values.b }}
both: true
{{- end }}

{{- if or .Values.a .Values.b }}
either: true
{{- end }}

# Loops
{{- range .Values.items }}
- {{ . }}
{{- end }}

{{- range $key, $value := .Values.map }}
{{ $key }}: {{ $value }}
{{- end }}

# Include template
{{- include "my-app.labels" . | nindent 4 }}

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

Dependencies

Add Dependencies

# Chart.yaml
dependencies:
  - name: postgresql
    version: "12.1.2"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled

  - name: redis
    version: "17.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: redis.enabled

# Download dependencies
helm dependency update

# Build dependencies
helm dependency build

Use Dependencies

# values.yaml
postgresql:
  enabled: true
  auth:
    database: mydb
    username: myuser
    password: mypassword

redis:
  enabled: true
  architecture: standalone

Testing Charts

Lint and Template

# Lint chart
helm lint ./my-chart

# Render templates locally
helm template my-release ./my-chart

# Render with custom values
helm template my-release ./my-chart -f production.yaml

# Dry run install
helm install my-release ./my-chart --dry-run --debug

Unit Tests

# Install helm-unittest plugin
helm plugin install https://github.com/helm-unittest/helm-unittest

# Run tests
helm unittest ./my-chart

# tests/deployment_test.yaml
suite: deployment tests
templates:
  - deployment.yaml
tests:
  - it: should have correct replicas
    set:
      replicaCount: 3
    asserts:
      - equal:
          path: spec.replicas
          value: 3

  - it: should use correct image
    set:
      image.repository: myapp
      image.tag: v1.0.0
    asserts:
      - equal:
          path: spec.template.spec.containers[0].image
          value: myapp:v1.0.0

Packaging and Publishing

# Package chart
helm package ./my-chart

# Create index for repo
helm repo index . --url https://example.com/charts

# Push to OCI registry
helm push my-chart-1.0.0.tgz oci://registry.example.com/charts

Summary

Command	Purpose
helm install	Deploy chart
helm upgrade	Update release
helm rollback	Revert release
helm template	Render templates
helm lint	Validate chart
helm package	Create package

Helm simplifies Kubernetes deployments with reusable, versioned, and parameterized charts.