DevOps & CI/CD Deep Dive · 11 of 18

Helm — apt-get for Kubernetes

A chart is a folder of templated YAML; values parameterize it per environment; a release tracks one install of a chart in a namespace. Helm is how almost every off-the-shelf Kubernetes app ships — Postgres, Prometheus, ingress controllers, you name it.

Chartsvalues.yamlTemplatesReleasesHooks
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Anatomy

What's in a Chart

Basic Concepts

  • Chart.yaml — name, version, app version, dependencies.
  • values.yaml — default config; users override per environment.
  • templates/ — Go-template'd YAML rendered with values.
  • _helpers.tpl — named template snippets (labels, fullname).
  • Subcharts — depend on other charts (e.g., bundle Postgres with your app).
  • Releases — Helm tracks history per release; helm rollback goes back to revision N.
Lifecycle

Install → Upgrade → Rollback

helm pull / repo add
→
values.yaml override
→
helm template (render)
→
helm install / upgrade
→
Release stored in cluster
→
helm rollback if needed
Helm vs Kustomize

Templating vs Patching

  • Helm templates strings — flexible but you can produce arbitrary YAML, valid or not, until rendered.
  • Kustomize overlays patch real K8s YAML — strongly typed, no Go template syntax. Built into kubectl.
  • Common pattern: ship apps as Helm charts; pin/override per cluster with Kustomize helmCharts:, or use Argo's chart + values pattern.
Tradeoffs

What to Watch Out For

  • Go templates inside YAML are awful to debug — invisible whitespace bugs, mis-indented blocks.
  • Charts you don't control can lag K8s API deprecations; pin versions and watch upstream.
  • Secrets management isn't built in — pair with SOPS, Sealed Secrets, or External Secrets.
  • Helm 2's Tiller is dead; if you ever see Tiller in a doc, the doc is from 2018.
  • Chart versions vs app versions confuse newcomers — bump both intentionally.
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