Helm Basics: Packaging Kubernetes Applications

Helm is a package manager for Kubernetes. A chart is a bundle of templated manifests; a release is an installed copy of a chart with your settings (values).

Installing software

helm repo add bitnami https://charts.bitnami.com/bitnami
helm search repo redis
helm show values bitnami/redis > redis-values.yaml   # see what you can configure
helm install cache bitnami/redis -n data --create-namespace -f redis-values.yaml
helm list -A

Many projects also publish charts as OCI artifacts: helm install x oci://registry.example.com/charts/x --version 1.2.3.

Creating a chart for your app

helm create api      # scaffolds Chart.yaml, values.yaml and templates/

# values.yaml
image:
  repository: ghcr.io/acme/api
  tag: "1.4.2"
replicaCount: 3
resources:
  requests: { cpu: 250m, memory: 256Mi }
  limits: { memory: 512Mi }

# templates/deployment.yaml (excerpt)
spec:
  replicas: {{ .Values.replicaCount }}
  template:
    spec:
      containers:
        - name: api
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

Per-environment values

helm upgrade --install api ./api -f values.yaml -f values-prod.yaml --set image.tag=$GIT_SHA
helm template api ./api -f values-prod.yaml      # render locally to review
helm history api
helm rollback api 3                               # back to revision 3

Helm or Kustomize?

• Helm: templating, packaging, versioned releases and rollbacks. Ideal for distributing software and for complex parameterisation.
• Kustomize (built into kubectl): patches plain YAML with overlays, no templating language. Simple for your own apps with small per-environment differences.
• Many teams use Helm for third-party software and Kustomize (or Helm) for their own services, applied by a GitOps tool.