Helm

Overview

Helm is the package manager for Kubernetes. It simplifies the deployment and management of Kubernetes applications by packaging them into charts - a collection of files that describe a related set of Kubernetes resources.

Installation

macOS (Homebrew)

brew install helm

Linux

curl https://get.helm.sh/helm-v3.12.0-linux-amd64.tar.gz | tar xz
sudo mv linux-amd64/helm /usr/local/bin/helm

Windows

# Using Chocolatey
choco install kubernetes-helm

# Using Scoop
scoop install helm

Verify Installation

helm version

Basic Concepts

Chart: A Helm package containing all resource definitions necessary to run an application
Repository: A collection of charts that can be shared
Release: An instance of a chart running in a Kubernetes cluster
Values: Configuration parameters that customize the chart

Repository Management

Add Official Helm Repository

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

Update Repository

helm repo update

List Repositories

helm repo list

Chart Operations

Search Charts

helm search repo nginx
helm search repo stable/nginx

Install Chart

# Install with default values
helm install my-release stable/nginx

# Install with custom values file
helm install my-release stable/nginx -f values.yaml

# Install with specific values
helm install my-release stable/nginx --set replicaCount=3

List Releases

helm list
helm list -n <namespace>

Upgrade Release

helm upgrade my-release stable/nginx
helm upgrade my-release stable/nginx --set replicaCount=5

Rollback Release

helm rollback my-release 1

Uninstall Release

helm uninstall my-release

Creating Custom Charts

Create New Chart

helm create my-chart

This creates a directory structure:

my-chart/
├── Chart.yaml
├── values.yaml
├── charts/
├── templates/
│   ├── _helpers.tpl
│   ├── deployment.yaml
│   ├── service.yaml
│   └── NOTES.txt
└── .helmignore

Chart.yaml Example

apiVersion: v2
name: my-application
description: A Helm chart for my application
type: application
version: 0.1.0
appVersion: "1.0.0"
keywords:
  - web
  - application
home: https://github.com/my-org/my-application
sources:
  - https://github.com/my-org/my-application
maintainers:
  - name: Your Name
    email: your.email@example.com

values.yaml Example

values.yaml

# Default values for my-application
replicaCount: 1

image:
  repository: nginx
  pullPolicy: IfNotPresent
  tag: "1.19"

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

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

podAnnotations: { }

podSecurityContext: { }

securityContext: { }

service:
  type: ClusterIP
  port: 80

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

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

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

Template Example (templates/deployment.yaml)

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: { { include "my-application.fullname" . } }
  labels:
    { { - include "my-application.labels" . | nindent 4 } }
spec:
  { { - if not .Values.autoscaling.enabled } }
  replicas: { { .Values.replicaCount } }
  { { - end } }
  selector:
    matchLabels:
      { { - include "my-application.selectorLabels" . | nindent 6 } }
  template:
    metadata:
      { { - with .Values.podAnnotations } }
      annotations:
        { { - toYaml . | nindent 8 } }
      { { - end } }
      labels:
        { { - include "my-application.selectorLabels" . | nindent 8 } }
    spec:
      { { - with .Values.imagePullSecrets } }
      imagePullSecrets:
        { { - toYaml . | nindent 8 } }
      { { - end } }
      serviceAccountName: { { include "my-application.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: 80
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              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 } }

Advanced Usage

Using Values Files

Create a custom values file (custom-values.yaml):

custom-values.yaml

replicaCount: 3
image:
  repository: my-registry/my-app
  tag: "2.0.0"
service:
  type: LoadBalancer
  port: 8080
resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 250m
    memory: 256Mi

Install with custom values:

helm install my-release ./my-chart -f custom-values.yaml

Override Values

helm install my-release ./my-chart \
  --set replicaCount=5 \
  --set image.tag=latest \
  --set service.type=NodePort

Template Rendering

Preview the rendered templates without installing:

helm template my-release ./my-chart
helm template my-release ./my-chart -f values.yaml

Package Chart

helm package ./my-chart

Install from Package

helm install my-release my-application-0.1.0.tgz

Best Practices

Chart Structure

Use meaningful names for charts and releases
Include comprehensive documentation in README.md
Use semantic versioning for chart versions
Provide sensible defaults in values.yaml
Use templates for reusable components

Security

Avoid hardcoding secrets in templates
Use Kubernetes secrets for sensitive data
Implement proper RBAC configurations
Use security contexts in pod specifications

Testing

# Lint chart
helm lint ./my-chart

# Test chart installation
helm test my-release

# Validate chart dependencies
helm dependency build ./my-chart

Dependencies

Add dependencies to Chart.yaml:

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

Install dependencies:

helm dependency update ./my-chart
helm dependency build ./my-chart

Common Commands Reference

# Chart management
helm create <chart-name>
helm package <chart-directory>
helm lint <chart-directory>

# Repository management
helm repo add <name> <url>
helm repo update
helm repo list
helm repo remove <name>

# Release management
helm install <release-name> <chart>
helm upgrade <release-name> <chart>
helm rollback <release-name> <revision>
helm uninstall <release-name>
helm list
helm status <release-name>

# Values and configuration
helm get values <release-name>
helm get manifest <release-name>
helm get hooks <release-name>

# Template operations
helm template <release-name> <chart>
helm show values <chart>
helm show chart <chart>
helm show readme <chart>