helm

name	helm
description	This skill should be used when authoring or maintaining Helm charts — creating charts, writing templates and _helpers.tpl, values.yaml patterns, Chart.yaml, values.schema.json, helm-docs, and library charts. Covers Helm 4 (SSA, WASM, OCI digest), chart CI/CD, OpenShift compatibility, chart security, CRD management, and production templates. NOT for installing or consuming third-party charts.
when_to_use	Triggers on Helm charts, _helpers.tpl, values.schema.json, helm-docs, library charts, helm-unittest, chart-testing, kubeconform, OCI push, SCCs, Routes, adaptSecurityContext, cosign signing, image digest pinning, SecurityContext, RBAC, NetworkPolicy, ServiceMonitor templates, HPA, persistence, or resource presets.

Helm Charts

Create, test, secure, and publish Helm charts. Covers Helm 4 (November 2025), OCI distribution, OpenShift compatibility, and production patterns from Bitnami, Cilium, cert-manager, and ArgoCD.

Quick Decision Guide

Task	Go to
Create a new chart from scratch	§ Chart Scaffold below
Structure values.yaml, helpers, labels	references/chart-structure.md
Harden security (SecurityContext, RBAC, NetworkPolicy)	references/security.md
Sign and verify charts (cosign, OCI)	references/security.md § Supply Chain
Make chart work on OpenShift	references/openshift.md
Write tests (unittest, ct, kubeconform)	references/testing-ci.md § Testing
Set up CI/CD (lint, test, release, OCI push)	references/testing-ci.md § CI/CD
Integrate release-please with Helm charts	references/testing-ci.md § Release-Please Integration
Add ServiceMonitor, HPA, persistence, extensions	references/production-patterns.md
Manage CRDs properly	references/chart-structure.md § CRDs
Multi-chart management (Helmfile)	references/testing-ci.md § Helmfile

Critical Gotchas

1. Helm 4 Is Current (Released November 2025)

Helm 4.0.0 released at KubeCon November 2025. Current: v4.2.0 (latest patch line v4.1.4 on the 4.1 series). Key changes:

• Server-Side Apply is default for new installations (existing Helm 3 releases keep client-side apply on upgrade unless --server-side is passed)
• OCI digest install: helm install app oci://registry/chart@sha256:abc...
• WASM plugin system (sandboxed). Post-renderers must be plugin names, not arbitrary executables
• CLI renames: --force -> --force-replace, --atomic -> --rollback-on-failure (old names emit deprecation warnings)
• Multi-document values files supported (--- separator)
• kstatus replaces --wait readiness checks. Annotations: helm.sh/readiness-success, helm.sh/readiness-failure
• Chart API v2 (Helm 3 charts) works unmodified. v3 format planned but not yet available
• Helm 3 EOL: bug fixes until July 8, 2026; security until November 11, 2026

2. Use include, Never template

template cannot be piped. include returns a string that works with nindent, quote, etc. Every named template call should use include:

# Wrong
{{ template "mychart.labels" . }}

# Right
{{- include "mychart.labels" . | nindent 4 }}

3. Namespace Named Templates to Avoid Collisions

ALL defined template names MUST be prefixed with the chart name. Global template namespace means unprefixed names collide with subcharts:

# Wrong
{{- define "fullname" -}}

# Right
{{- define "mychart.fullname" -}}

4. Selector Labels Are Immutable

Never include version-based labels in Deployment matchLabels. Use only:

• app.kubernetes.io/name (chart name)
• app.kubernetes.io/instance (release name)

Adding helm.sh/chart or app.kubernetes.io/version to selectors causes upgrade failures because matchLabels cannot be changed after creation.

5. values.yaml: camelCase, Quote Strings, Prefer Maps

• camelCase with lowercase first letter (never .Release.Name case for user values)
• Quote all strings: {{ .Values.foo | quote }} (prevents YAML type coercion)
• Prefer maps over arrays for --set ergonomics
• Large integers can become scientific notation; store as strings if needed

6. CRDs in crds/ Directory Are Never Upgraded

Helm's native crds/ directory installs CRDs once but never upgrades or deletes them. Every major chart (cert-manager, Cilium, kube-prometheus-stack) avoids this by putting CRDs in templates/ with conditional flags. See references/chart-structure.md § CRDs.

7. OCI Is the Primary Distribution Method

OCI registries are the recommended distribution for Helm 4. Bitnami moved to OCI-only. Push: helm push chart-0.1.0.tgz oci://ghcr.io/org/charts. Tags must match SemVer (no latest). SemVer + becomes _ in OCI tags.

8. OpenShift: Omit Specific UIDs

OpenShift assigns random UIDs per namespace. Charts that hardcode runAsUser: 1001 break under the restricted-v2 SCC. Use the Bitnami adaptSecurityContext: auto pattern to auto-detect OpenShift and strip UID/GID fields. See references/openshift.md.

9. DeploymentConfig Is Dead

Deprecated in OpenShift 4.14. Use standard apps/v1 Deployment. Never create new DeploymentConfigs.

10. Default LoadBalancer Services to No NodePort, and Add extraSpec

Kubernetes auto-assigns a NodePort (30000-32767) for LoadBalancer services. This is almost never wanted — cloud LBs route traffic directly. Default allocateLoadBalancerNodePorts: false in values.yaml. Requires Kubernetes 1.24+.

Additionally, always include service.extraSpec: {} — a passthrough map that renders arbitrary fields into the Service spec via toYaml. This prevents admins from being blocked when they need externalTrafficPolicy, internalTrafficPolicy, loadBalancerClass, or any future K8s field. See references/production-patterns.md § Service Spec Control.

11. Always Provide commonAnnotations and commonLabels

Every chart must include commonAnnotations: {} and commonLabels: {} at the top of values.yaml. These apply to every resource metadata block — critical for cost allocation, team ownership, compliance, and tooling that filters by labels or annotations (Prometheus, ArgoCD, Datadog, etc.). Inject commonLabels via the labels helper; create a dedicated annotations helper for commonAnnotations. For resources with their own annotations (Service, Ingress, ServiceAccount), merge both. See references/chart-structure.md § Common Labels and Annotations.

12. release-please: Three Traps That Break Chart Publishing

Trap 1: release-type as action input ignores config file. If you set release-type: go (or any value) in the workflow YAML, the action calls Manifest.fromConfig() which builds config entirely from inputs and completely skips release-please-config.json. All advanced config (extra-files, changelog-sections, draft, etc.) is silently ignored. Always put release-type in the config file, never in the action input.

Trap 2: String form of extra-files strips YAML comments. The shorthand "charts/mychart/Chart.yaml" runs GenericYaml first, which strips all comments including x-release-please-version annotations. Use the object form: {"type": "generic", "path": "charts/mychart/Chart.yaml"}.

Trap 3: Missing changelog-sections dumps ci: into "Breaking Changes". Without explicit section config, unrecognized commit types land in a catch-all "Breaking Changes" section. Always configure changelog-sections with hidden: true for non-user-facing types.

See references/testing-ci.md § Release-Please Integration for full config.

13. Cosign Requires Separate Registry Auth from Helm

helm registry login ghcr.io authenticates Helm's OCI client but does NOT authenticate cosign. If your CI workflow pushes a chart with Helm and then signs with cosign, you need both:

# Helm auth (for helm push)
- uses: docker/login-action@...   # or: helm registry login ghcr.io

# Cosign auth (for cosign sign) — SEPARATE step
- run: cosign login ghcr.io -u ${{ github.actor }} -p ${{ secrets.GITHUB_TOKEN }}

Without the cosign login, signing fails with auth errors even though the push succeeded. See the OCI Push workflow in references/testing-ci.md.

14. Renovate Is Significantly Better Than Dependabot for Helm

Dependabot added Helm support April 2025 but only handles Chart.yaml dependency versions. Renovate also updates image tags in values.yaml, auto-bumps chart versions, supports regex managers, and is self-hostable for air-gapped setups.

Chart Scaffold

Start with helm create mychart, then apply these patterns:

mychart/
  .helmignore          # Exclude .git/, .github/, *.key, *.pem, .env
  Chart.yaml           # apiVersion: v2, type: application
  values.yaml          # camelCase, documented properties
  values.schema.json   # JSON Schema for validation
  README.md            # Auto-generate with helm-docs
  charts/              # Dependency charts
  crds/                # Only if CRDs never need upgrading
  templates/
    _helpers.tpl       # Namespaced named templates
    deployment.yaml    # One resource per file
    service.yaml
    serviceaccount.yaml
    ingress.yaml
    networkpolicy.yaml
    hpa.yaml
    pdb.yaml
    NOTES.txt          # Post-install instructions
    tests/
      test-connection.yaml

Minimal Chart.yaml

apiVersion: v2
name: mychart
description: A Helm chart for MyApp
type: application
version: 0.1.0
appVersion: "1.0.0"
kubeVersion: ">=1.22.0"
dependencies:
  - name: common
    version: ~2.x
    repository: oci://registry-1.docker.io/bitnamicharts
    tags:
      - bitnami-common

Complete starter _helpers.tpl, values.yaml, and other templates are in references/chart-structure.md § Starter Templates. Key values patterns:

• image.registry/repository/tag/digest (Bitnami standard, digest overrides tag)
• serviceAccount.create/automount: false (security: no auto-mounted token)
• containerSecurityContext targeting PSS restricted profile
• global.compatibility.openshift.adaptSecurityContext: auto for OpenShift

Reference Files

• references/chart-structure.md — Starter templates, Chart.yaml, values, helpers, labels, library charts, OCI, deps, schema, helm-docs, CRDs
• references/security.md — SecurityContext, RBAC, NetworkPolicy, image digests, secrets, cosign signing, Flux/ArgoCD verification
• references/openshift.md — Detection, SCCs, Routes vs Ingress, arbitrary UIDs, adaptSecurityContext, service certs, certification
• references/testing-ci.md — Testing pyramid, helm-unittest, ct, kubeconform, security scanning, CI workflows, Helmfile, Renovate
• references/production-patterns.md — ServiceMonitor, HPA, PDB, persistence, checksums, extension points, multi-component, presets