3.1.4.X. Container Deployment with Helm Charts

Helm is the package manager for Kubernetes — it bundles all the YAML manifests (deployments, services, configmaps, secrets) that define an application into a single, versioned, parameterized unit called a chart.

💡 Why this matters for AZ-400: The exam tests your ability to implement application deployment using containers. While Azure Pipelines and GitHub Actions can deploy raw Kubernetes manifests, real-world AKS deployments almost always use Helm because it solves three critical problems: templating (one chart, multiple environments), versioning (rollback to a specific chart version), and dependency management (chart of charts).

Core Helm concepts:

• Chart: A directory of templated Kubernetes manifests plus a Chart.yaml metadata file and a values.yaml defaults file
• Release: A specific deployment of a chart to a cluster. Each helm install or helm upgrade creates a release with a revision number
• Repository: A hosted collection of charts (e.g., Azure Container Registry can serve as a Helm repo via az acr helm)
• Values override: helm upgrade my-app ./chart --set image.tag=v2.1.0 or -f production-values.yaml to customize per environment

Pipeline integration pattern:

Build Stage → Push image to ACR → Helm Upgrade Stage → helm upgrade --install \
  --set image.repository=$(ACR_NAME).azurecr.io/myapp \
  --set image.tag=$(Build.BuildId) \
  --namespace production \
  my-release ./helm-chart

⚠️ Exam Tip: Know the difference between helm install (first deployment) and helm upgrade --install (idempotent — installs if missing, upgrades if present). The --install flag is critical for CI/CD pipelines because it makes the command safe to run repeatedly.