Free course · 12 lessons · Advanced
Helm, Kustomize and GitOps with Argo CD
Package and deliver Kubernetes applications safely: values schemas that catch typos, template indentation bugs, upgrades blocked by immutable fields, pinned chart dependencies, Kustomize bases and overlays, patches that delete what you meant to keep, then GitOps with Argo CD: drift and self-heal, sync waves and hooks for migrations, ApplicationSets for many clusters, secrets, and promotion between environments. Helm and Kustomize examples run the real tools.
1. Helm Charts That Don't Surprise You
Silently ignored values, broken indentation, upgrades that fail on immutable fields and dependencies that change underneath you.
- Typos in Values That Helm Silently Ignores — A misspelled value falls back to the chart default without any warning; a values schema turns it into an error.
- Broken YAML from Template Indentation — toYaml without the right indentation renders manifests that are invalid or, worse, valid but wrong; render and validate in CI.
- Upgrades That Fail on Immutable Fields — Changing a Deployment's selector labels makes helm upgrade fail; know which fields are immutable and how to migrate safely.
- Unpinned Chart Dependencies — Version ranges in Chart.yaml pull in new subchart versions on rebuild; lock and review dependency updates.
2. Kustomize Without the Mess
Copy-pasted environment folders that drift, and patches that silently delete what you meant to keep.
- Copy-Pasted Environments That Drift — Duplicated manifests per environment drift apart; a base with small overlays and components keeps differences explicit.
- Patches That Delete What You Meant to Keep — A JSON patch replacing a list or a strategic merge patch with the wrong merge key silently drops configuration; check the rendered output.
3. GitOps with Argo CD
Git as the source of truth: drift and self-healing, ordering with sync waves and hooks, many clusters with ApplicationSets, secrets, and promotion between environments.
- Manual Changes That Quietly Undo GitOps — A hotfix applied with kubectl survives until the next sync overwrites it, or never gets reverted; configure self-heal and prune deliberately.
- Deploying Before the Database Migration Ran — Argo CD applies resources in an order you must control; sync waves and hooks run migrations before the new version starts.
- Copy-Pasted Applications for Every Cluster — Hundreds of hand-written Application manifests drift and get forgotten; ApplicationSets generate them from clusters, directories or lists.
- Secrets Committed to the GitOps Repository — A Secret manifest in Git is plaintext for anyone with repository access; encrypt it or keep only references in Git.
- Promotion Between Environments by Copy and Paste — Hand-edited image tags per environment let untested versions reach production; promote the same artefact through gates.
4. Capstone
Design a GitOps delivery platform.
- Capstone: A GitOps Platform for Three Environments and Many Teams — Design repositories, packaging, Argo CD structure, secrets and promotion for 25 services across dev, staging and production.