Helm Package Management

Helm is the package manager for Kubernetes. It simplifies deploying and managing complex applications by packaging Kubernetes manifests into reusable charts with configurable values. This lesson covers Helm concepts, chart creation, templating, hooks, and Helmfile for multi-chart management.

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Helm Concepts

Concept	Description
Chart	A package of Kubernetes resource templates
Release	A deployed instance of a chart
Values	Configuration overrides for chart templates
Repository	A collection of charts (like a package registry)
Revision	A versioned snapshot of a release

┌─────────────┐     ┌─────────────┐     ┌──────────────┐
│  Chart       │  +  │  Values     │  =  │  Release     │
│  (templates) │     │  (config)   │     │  (deployed)  │
└─────────────┘     └─────────────┘     └──────────────┘

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Essential Helm Commands

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

# Search for charts
helm search repo nginx
helm search hub prometheus

# Install a chart
helm install my-nginx bitnami/nginx --namespace web --create-namespace

# Install with custom values
helm install my-app ./my-chart -f values-production.yaml

# Upgrade a release
helm upgrade my-app ./my-chart -f values-production.yaml

# Install or upgrade (idempotent)
helm upgrade --install my-app ./my-chart -f values-production.yaml

# Roll back to a previous revision
helm rollback my-app 2

# List releases
helm list --all-namespaces

# Uninstall a release
helm uninstall my-app --namespace web

# View release history
helm history my-app

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Chart Structure

my-chart/
├── Chart.yaml              # Chart metadata (name, version, dependencies)
├── values.yaml             # Default configuration values
├── templates/
│   ├── _helpers.tpl        # Template helper functions
│   ├── deployment.yaml     # Deployment template
│   ├── service.yaml        # Service template
│   ├── ingress.yaml        # Ingress template
│   ├── hpa.yaml            # HorizontalPodAutoscaler template
│   ├── configmap.yaml      # ConfigMap template
│   ├── secret.yaml         # Secret template
│   └── NOTES.txt           # Post-install notes
├── charts/                 # Dependency charts
└── .helmignore             # Files to ignore when packaging

Chart.yaml

apiVersion: v2
name: my-chart
description: A Helm chart for My Application
type: application
version: 1.2.0              # Chart version
appVersion: "3.1.0"         # Application version
dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled

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Helm Templating

Helm uses Go templates to generate Kubernetes manifests dynamically.

values.yaml

replicaCount: 3

image:
  repository: myapp/web-api
  tag: "v2.1.0"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

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

ingress:
  enabled: true
  host: app.example.com

autoscaling:
  enabled: true
  minReplicas: 3
  maxReplicas: 10
  targetCPUUtilization: 70

templates/deployment.yaml