Helm: Complete Kubernetes Package Manager Guide

🎯 Introduction

Helm is the package manager for Kubernetes, simplifying application deployment and management through reusable packages called charts. It enables you to define, install, and upgrade complex Kubernetes applications.

Why Helm?

Key Benefits:

Package Management: Bundle Kubernetes resources into charts
Template System: Parameterize deployments with values
Version Control: Manage application versions
Dependency Management: Handle chart dependencies
Rollback: Easy rollback to previous versions
Release Management: Track deployed releases
Large Ecosystem: 10,000+ charts available

Helm Concepts

Chart: Package of Kubernetes resources
Release: Installed chart instance
Values: Configuration parameters
Templates: Kubernetes manifests with variables
Repository: Chart storage location

📚 Chart Structure

Standard Chart Layout

mychart/
├── Chart.yaml              # Chart metadata
├── values.yaml             # Default values
├── charts/                 # Chart dependencies
├── templates/              # Template files
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── _helpers.tpl        # Helper templates
│   └── NOTES.txt           # Installation notes
└── templates/tests/        # Test files
    └── test-connection.yaml

📝 Complete Chart Examples

Chart.yaml

apiVersion: v2
name: myapp
description: A Helm chart for my application
type: application
version: 1.0.0
appVersion: "1.0.0"
keywords:
  - web
  - application
home: https://example.com
sources:
  - https://github.com/user/repo
maintainers:
  - name: DevOps Team
    email: devops@example.com
dependencies:
  - name: postgresql
    version: "12.0.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled

values.yaml

# Default values
replicaCount: 3

image:
  repository: nginx
  pullPolicy: IfNotPresent
  tag: "1.21"

imagePullSecrets: []
nameOverride: ""
fullnameOverride: ""

serviceAccount:
  create: true
  annotations: {}
  name: ""

podAnnotations: {}

podSecurityContext: {}
  # fsGroup: 2000

securityContext: {}
  # capabilities:
  #   drop:
  #   - ALL
  # readOnlyRootFilesystem: true
  # runAsNonRoot: true
  # runAsUser: 1000

service:
  type: ClusterIP
  port: 80
  targetPort: 80

ingress:
  enabled: false
  className: "nginx"
  annotations: {}
    # kubernetes.io/ingress.class: nginx
    # kubernetes.io/tls-acme: "true"
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
          pathType: Prefix
  tls: []
  #  - secretName: myapp-tls
  #    hosts:
  #      - myapp.example.com

resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 250m
    memory: 256Mi

autoscaling:
  enabled: false
  minReplicas: 1
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

nodeSelector: {}

tolerations: []

affinity: {}

# PostgreSQL dependency
postgresql:
  enabled: true
  auth:
    postgresPassword: "changeme"
    database: "myapp"

templates/deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  selector:
    matchLabels:
      {{- include "myapp.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      annotations:
        checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
        {{- with .Values.podAnnotations }}
        {{- toYaml . | nindent 8 }}
        {{- end }}
      labels:
        {{- include "myapp.selectorLabels" . | nindent 8 }}
    spec:
      {{- with .Values.imagePullSecrets }}
      imagePullSecrets:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      serviceAccountName: {{ include "myapp.serviceAccountName" . }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
        - name: {{ .Chart.Name }}
          securityContext:
            {{- toYaml .Values.securityContext | nindent 12 }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: {{ .Values.service.targetPort }}
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              port: http
          resources:
            {{- toYaml .Values.resources | nindent 12 }}
          env:
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: {{ include "myapp.fullname" . }}-postgresql
                  key: postgresql-password
      {{- with .Values.nodeSelector }}
      nodeSelector:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.affinity }}
      affinity:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.tolerations }}
      tolerations:
        {{- toYaml . | nindent 8 }}
      {{- end }}

templates/service.yaml

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

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 }}
{{- if contains $name .Release.Name }}
{{- .Release.Name | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}
{{- end }}

{{/*
Create chart name and version as used by the chart label.
*/}}
{{- define "myapp.chart" -}}
{{- printf "%s-%s" .Chart.Name .Chart.Version | replace "+" "_" | trunc 63 | trimSuffix "-" }}
{{- end }}

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

{{/*
Create the name of the service account to use
*/}}
{{- define "myapp.serviceAccountName" -}}
{{- if .Values.serviceAccount.create }}
{{- default (include "myapp.fullname" .) .Values.serviceAccount.name }}
{{- else }}
{{- default "default" .Values.serviceAccount.name }}
{{- end }}
{{- end }}

🔧 Helm Commands

Chart Management

# Create new chart
helm create mychart

# Package chart
helm package mychart

# Install chart
helm install myapp ./mychart
helm install myapp ./mychart -n production
helm install myapp ./mychart --set replicaCount=5
helm install myapp ./mychart -f values-production.yaml

# Upgrade release
helm upgrade myapp ./mychart
helm upgrade myapp ./mychart --set image.tag=v2.0.0
helm upgrade myapp ./mychart --reuse-values

# Rollback
helm rollback myapp
helm rollback myapp 2  # To revision 2

# Uninstall
helm uninstall myapp
helm uninstall myapp -n production

Release Management

# List releases
helm list
helm list -A  # All namespaces
helm list --all  # Including failed

# Get release info
helm get all myapp
helm get values myapp
helm get manifest myapp
helm get notes myapp
helm get hooks myapp

# History
helm history myapp

Repository Management

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

# List repositories
helm repo list

# Update repositories
helm repo update

# Search charts
helm search repo nginx
helm search repo bitnami/nginx

# Remove repository
helm repo remove bitnami

Template and Testing

# Template (dry-run)
helm template myapp ./mychart
helm template myapp ./mychart --values values.yaml
helm template myapp ./mychart --debug

# Lint chart
helm lint ./mychart

# Test chart
helm test myapp

Dependency Management

# Update dependencies
helm dependency update ./mychart

# Build dependencies
helm dependency build ./mychart

# List dependencies
helm dependency list ./mychart

🎯 Advanced Features

Chart Dependencies

Chart.yaml:

dependencies:
  - name: postgresql
    version: "12.0.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled
    tags:
      - database

values.yaml:

postgresql:
  enabled: true
  auth:
    postgresPassword: "changeme"

Hooks

# Pre-install hook
apiVersion: batch/v1
kind: Job
metadata:
  name: pre-install-job
  annotations:
    "helm.sh/hook": pre-install
    "helm.sh/hook-weight": "-5"
    "helm.sh/hook-delete-policy": before-hook-creation
spec:
  template:
    spec:
      containers:
        - name: pre-install
          image: busybox
          command: ['sh', '-c', 'echo Pre-install hook']
      restartPolicy: Never

Tests

templates/tests/test-connection.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: "{{ include "myapp.fullname" . }}-test-connection"
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
  annotations:
    "helm.sh/hook": test
spec:
  containers:
    - name: wget
      image: busybox
      command: ['wget']
      args: ['{{ include "myapp.fullname" . }}:{{ .Values.service.port }}']
  restartPolicy: Never

✅ Best Practices

1. Version Charts Properly

# Use semantic versioning
version: 1.0.0
appVersion: "1.0.0"

2. Use Values for Configuration

# Don't hardcode values
# Use .Values for all configuration
replicas: {{ .Values.replicaCount }}

3. Document Charts

# Chart.yaml
description: Clear description
home: Project homepage
sources: Source code location
maintainers: Maintainer information

4. Test Before Release

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

5. Use Helpers

# _helpers.tpl for reusable templates
{{- define "myapp.labels" -}}
# ...
{{- end }}

✅ Mastery Checklist

Next Steps:

Learn Kubernetes Operations
Explore Argo CD for GitOps
Master Terraform for infrastructure

Remember: Helm simplifies Kubernetes deployments. Use values for configuration, test charts thoroughly, and version properly. Start with simple charts and gradually add complexity.

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Helm: Complete Kubernetes Package Manager Guide

🎯 Introduction

Why Helm?

Helm Concepts

📚 Chart Structure

Standard Chart Layout

📝 Complete Chart Examples

Chart.yaml

values.yaml

templates/deployment.yaml

templates/service.yaml

templates/_helpers.tpl

🔧 Helm Commands

Chart Management

Release Management

Repository Management

Template and Testing

Dependency Management

🎯 Advanced Features

Chart Dependencies

Hooks

Tests

✅ Best Practices

1. Version Charts Properly

2. Use Values for Configuration

3. Document Charts

4. Test Before Release

5. Use Helpers

✅ Mastery Checklist

FilesExpand file tree

helm.md

Latest commit

History

helm.md

File metadata and controls

Helm: Complete Kubernetes Package Manager Guide

🎯 Introduction

Why Helm?

Helm Concepts

📚 Chart Structure

Standard Chart Layout

📝 Complete Chart Examples

Chart.yaml

values.yaml

templates/deployment.yaml

templates/service.yaml

templates/_helpers.tpl

🔧 Helm Commands

Chart Management

Release Management

Repository Management

Template and Testing

Dependency Management

🎯 Advanced Features

Chart Dependencies

Hooks

Tests

✅ Best Practices

1. Version Charts Properly

2. Use Values for Configuration

3. Document Charts

4. Test Before Release

5. Use Helpers

✅ Mastery Checklist