Helm - Kubernetes Package Manager¶

Helm is the package manager for Kubernetes, simplifying application deployment and management.

Helm Overview¶

┌────────────────────────────────────────┐
│          Helm Architecture             │
├────────────────────────────────────────┤
│                                        │
│  Helm CLI  ──────►  Kubernetes API     │
│                                        │
│  Chart (Package)                       │
│    ├── templates/                      │
│    ├── values.yaml                     │
│    └── Chart.yaml                      │
│                                        │
│  Release (Deployed Instance)           │
└────────────────────────────────────────┘

Installation¶

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

# Install Helm (macOS)
brew install helm

# Verify installation
helm version

Core Concepts¶

Chart¶

Package containing Kubernetes resource definitions

Release¶

Instance of a chart running in cluster

Repository¶

Collection of charts

Values¶

Configuration parameters for charts

Basic Commands¶

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

# Update repositories
helm repo update

# Search charts
helm search repo nginx
helm search hub wordpress

# Install chart
helm install my-release bitnami/nginx

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

# Get release status
helm status my-release

# Upgrade release
helm upgrade my-release bitnami/nginx

# Rollback release
helm rollback my-release 1

# Uninstall release
helm uninstall my-release

# Get values
helm get values my-release

# Get manifest
helm get manifest my-release

Chart Structure¶

mychart/
├── Chart.yaml          # Chart metadata
├── values.yaml         # Default values
├── charts/             # Dependencies
├── templates/          # Kubernetes manifests
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── _helpers.tpl   # Template helpers
│   └── NOTES.txt      # Post-install notes
├── .helmignore        # Files to ignore
└── README.md          # Documentation

Chart.yaml¶

apiVersion: v2
name: myapp
description: A Helm chart for my application
type: application
version: 1.0.0
appVersion: "1.0"
keywords:
  - web
  - application
home: https://example.com
sources:
  - https://github.com/example/myapp
maintainers:
  - name: John Doe
    email: john@example.com
dependencies:
  - name: postgresql
    version: 12.x.x
    repository: https://charts.bitnami.com/bitnami

values.yaml¶

# Default values for myapp
replicaCount: 3

image:
  repository: myapp
  pullPolicy: IfNotPresent
  tag: "1.0"

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

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

podAnnotations: {}

podSecurityContext:
  runAsNonRoot: true
  runAsUser: 1000

securityContext:
  allowPrivilegeEscalation: false
  readOnlyRootFilesystem: true

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  className: "nginx"
  annotations: {}
  hosts:
    - host: chart-example.local
      paths:
        - path: /
          pathType: Prefix
  tls: []

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

autoscaling:
  enabled: false
  minReplicas: 1
  maxReplicas: 100
  targetCPUUtilizationPercentage: 80

nodeSelector: {}

tolerations: []

affinity: {}

Template Example¶

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:
      {{- with .Values.podAnnotations }}
      annotations:
        {{- 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: 8080
          protocol: TCP
        livenessProbe:
          httpGet:
            path: /healthz
            port: http
        readinessProbe:
          httpGet:
            path: /ready
            port: http
        resources:
          {{- toYaml .Values.resources | nindent 12 }}
      {{- with .Values.nodeSelector }}
      nodeSelector:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.affinity }}
      affinity:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.tolerations }}
      tolerations:
        {{- toYaml . | nindent 8 }}
      {{- end }}

_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 }}

{{/*
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 }}

Installing Charts¶

Basic Install¶

# Install from repository
helm install my-release bitnami/nginx

# Install with custom values
helm install my-release bitnami/nginx --values custom-values.yaml

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

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

# Dry run
helm install my-release bitnami/nginx --dry-run --debug

# Generate manifest without installing
helm template my-release bitnami/nginx

Custom Values File¶

# custom-values.yaml
replicaCount: 5

image:
  tag: "1.21"

service:
  type: LoadBalancer
  port: 8080

ingress:
  enabled: true
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
          pathType: Prefix

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

helm install my-release bitnami/nginx -f custom-values.yaml

Upgrading Releases¶

# Upgrade with new values
helm upgrade my-release bitnami/nginx --values new-values.yaml

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

# Upgrade or install
helm upgrade --install my-release bitnami/nginx

# Force upgrade
helm upgrade my-release bitnami/nginx --force

# Upgrade with wait
helm upgrade my-release bitnami/nginx --wait --timeout 5m

# Upgrade with atomic (rollback on failure)
helm upgrade my-release bitnami/nginx --atomic

Rollback¶

# List revisions
helm history my-release

# Rollback to previous version
helm rollback my-release

# Rollback to specific revision
helm rollback my-release 2

# Rollback with wait
helm rollback my-release 2 --wait

Creating Charts¶

# Create new chart
helm create myapp

# Lint chart
helm lint myapp/

# Package chart
helm package myapp/

# Install local chart
helm install my-release ./myapp

# Install packaged chart
helm install my-release myapp-1.0.0.tgz

Dependencies¶

Chart.yaml¶

dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled
  - name: redis
    version: "17.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: redis.enabled

Manage Dependencies¶

# Update dependencies
helm dependency update myapp/

# List dependencies
helm dependency list myapp/

# Build dependencies
helm dependency build myapp/

Hooks¶

Execute actions at specific points:

apiVersion: batch/v1
kind: Job
metadata:
  name: {{ include "myapp.fullname" . }}-migration
  annotations:
    "helm.sh/hook": pre-upgrade,pre-install
    "helm.sh/hook-weight": "0"
    "helm.sh/hook-delete-policy": before-hook-creation
spec:
  template:
    spec:
      containers:
      - name: migration
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        command: ["./migrate.sh"]
      restartPolicy: Never

Hook Types: - pre-install: Before resources are installed - post-install: After all resources are installed - pre-delete: Before resources are deleted - post-delete: After all resources are deleted - pre-upgrade: Before resources are upgraded - post-upgrade: After all resources are upgraded - pre-rollback: Before rollback - post-rollback: After rollback - test: When helm test is run

Testing¶

# 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 my-release

# Run tests with logs
helm test my-release --logs

Helm Plugins¶

# List plugins
helm plugin list

# Install plugin
helm plugin install https://github.com/databus23/helm-diff

# Use diff plugin
helm diff upgrade my-release bitnami/nginx --values new-values.yaml

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

# Use secrets
helm secrets install my-release ./myapp -f secrets.yaml

Repository Management¶

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

# List repositories
helm repo list

# Update repositories
helm repo update

# Remove repository
helm repo remove bitnami

# Search repository
helm search repo nginx

# Search hub
helm search hub wordpress

Best Practices¶

Version Control
Store charts in Git
Use semantic versioning
Tag releases
Values Organization
Use descriptive names
Group related values
Document all values
Templates
Use helpers for common patterns
Keep templates simple
Add comments
Testing
Lint charts before packaging
Test installations
Use helm test
Security
Don't commit secrets
Use helm-secrets plugin
Scan charts for vulnerabilities
Documentation
Maintain README
Document values
Add NOTES.txt

Troubleshooting¶

# Debug installation
helm install my-release ./myapp --debug --dry-run

# Get release manifest
helm get manifest my-release

# Get release values
helm get values my-release

# Get all release info
helm get all my-release

# View release history
helm history my-release

# Check release status
helm status my-release

# List all releases
helm list --all-namespaces

# Uninstall with keep history
helm uninstall my-release --keep-history

Common Issues¶

Chart not found

helm repo update
helm search repo <chart-name>

Values not applied

helm get values my-release
helm upgrade my-release ./myapp --values values.yaml --debug

Template errors

helm lint ./myapp
helm template my-release ./myapp --debug

Helm - Kubernetes Package Manager¶

Helm Overview¶

Installation¶

Core Concepts¶

Chart¶

Release¶

Repository¶

Values¶

Basic Commands¶

Chart Structure¶

Chart.yaml¶

values.yaml¶

Template Example¶

deployment.yaml¶

_helpers.tpl¶

Installing Charts¶

Basic Install¶

Custom Values File¶

Upgrading Releases¶

Rollback¶

Creating Charts¶

Dependencies¶

Chart.yaml¶

Manage Dependencies¶

Hooks¶

Testing¶

Helm Plugins¶

Repository Management¶

Best Practices¶

Troubleshooting¶

Common Issues¶

References¶