09 - Helm & Package Management

Why this matters

Real applications aren't one YAML file — they're dozens, parameterized per environment. Helm is the de facto package manager for Kubernetes; almost every prod cluster uses it or something like it (Kustomize is the other major option — know both).

Read this first — Definitions & Explanations

Helm

The common package manager for Kubernetes. It templates YAML and installs it as a versioned release.

Chart

A package of templates + default values that describes an application (Deployments, Services, etc.).

values.yaml

Configuration knobs for a chart (image tag, replica count, ingress host). You override values per environment.

Release

An installed instance of a chart in a cluster/namespace (helm install my-app ./chart).

helm upgrade / rollback

• upgrade: apply a new chart version or values
• rollback: return a release to a previous revision

Repository

A place that hosts charts (helm repo add ...).

Why Helm helps

Keeps complex apps maintainable, repeatable, and parameterized instead of copying raw YAML forever.

Official docs (read for detail)

• Helm Docs
• Helm Charts Guide
• Chart Best Practices
• Kubernetes Package Management overview (objects Helm renders)

Key Concepts

• Chart = templated collection of manifests + values.yaml
• Release = a deployed instance of a chart (can install same chart multiple times)
• helm install/upgrade/rollback/uninstall
• Chart repositories, Chart.yaml, dependencies (subcharts)
• Templating: {{ .Values.x }}, {{ include }}, {{ if }}, ranges
• Helm vs Kustomize: templating engine vs patch-based overlays — know the tradeoffs
• helm diff plugin for safe upgrades, --dry-run / --debug

YouTube search terms

• "Helm charts explained Kubernetes"
• "Helm vs Kustomize"
• "Writing your first Helm chart tutorial"

Hands-on lab (on prod-sim)

# Install something real via Helm
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update
helm install my-nginx bitnami/nginx --set replicaCount=2
helm list
helm status my-nginx

# Upgrade and rollback
helm upgrade my-nginx bitnami/nginx --set replicaCount=4
helm history my-nginx
helm rollback my-nginx 1

# Write your own minimal chart
helm create mychart
# edit mychart/values.yaml: change replicaCount to 2, image.repository to nginx
helm install test-release ./mychart --dry-run --debug   # render without applying
helm install test-release ./mychart
kubectl get deployments -l app.kubernetes.io/instance=test-release
helm uninstall test-release
helm uninstall my-nginx

Notes

(fill in your own words after watching + labbing)