Helm Chart Review Skill

Helm Chart Review

Purpose

Provide comprehensive review checklists and automated validation for ensuring Helm charts meet production quality and security standards before deployment.

Complete Review Workflow

Step 1: Run Automated Validation

# Lint checks
helm lint ./charts/mychart

# Template rendering validation
helm template mychart ./charts/mychart --debug

# Test with different value files
helm template mychart ./charts/mychart -f values-prod.yaml

# Dry run installation
helm install test ./charts/mychart --dry-run --debug --namespace test

Step 2: Security Review Checklist

Critical security items (must pass):

[ ] No hardcoded secrets in values.yaml or templates
[ ] Image tags are specific (no :latest tag)

[ ] Security contexts are defined and restrictive:

securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false
  capabilities:
    drop:
      - ALL

[ ] RBAC is properly configured with least privilege
[ ] Resource limits are set for all containers
[ ] Service accounts are explicitly created (not using default)
[ ] Secrets use external secret management (not inline)

Security red flags:

# ❌ NEVER allow these
securityContext:
  privileged: true # Unacceptable
  runAsUser: 0 # Root user - requires justification
  allowPrivilegeEscalation: true # Security risk

image:
  tag: latest # Non-deterministic

# Hardcoded secrets
password: "hardcoded123" # NEVER hardcode secrets

Step 3: Structure Review Checklist

[ ] Chart.yaml has all required fields:
- apiVersion: v2
- name, description, type
- version (follows SemVer2)
- appVersion
- maintainers with contact info
[ ] Version follows SemVer2 format (MAJOR.MINOR.PATCH)
[ ] Dependencies use version ranges (~)
[ ] One resource per file in templates/
[ ] Template helpers are properly namespaced
[ ] File naming follows conventions (lowercase, dashes)
[ ] NOTES.txt provides useful post-install information
[ ] README.md exists with usage documentation

Step 4: Values Review Checklist

[ ] All values are documented with clear comments
[ ] Naming is consistent (camelCase throughout)
[ ] Types are explicit (strings quoted: tag: "1.0")
[ ] Flat structure preferred over deep nesting
[ ] Defaults are secure and production-ready
[ ] Environment-specific values separated (values-{env}.yaml)
[ ] Boolean values use lowercase (true/false)
[ ] Resource requests/limits have realistic values

Good vs bad values:

# ✅ Good
replicaCount: 2 # Documented, reasonable default

image:
  repository: myapp
  pullPolicy: IfNotPresent
  tag: "" # Empty, uses appVersion

resources:
  limits:
    cpu: 500m
    memory: 256Mi
  requests:
    cpu: 250m
    memory: 128Mi

# ❌ Bad
replicas: 1 # Undocumented, single point of failure
ImageTag: latest # Wrong case, non-specific tag
database:
  password: "changeme" # Hardcoded secret

Step 5: Template Review Checklist

[ ] Labels are consistent and follow k8s recommendations:
- app.kubernetes.io/name
- app.kubernetes.io/instance
- app.kubernetes.io/version
- app.kubernetes.io/managed-by
[ ] Nil checks for nested values (prevent nil pointer errors)
[ ] Whitespace properly managed ({{- and -}} used correctly)
[ ] Helper functions used for repeated logic
[ ] Conditionals properly structured
[ ] Resources can be disabled via values
[ ] Image tags default to Chart.AppVersion
[ ] ConfigMap/Secret changes trigger pod restarts (checksum annotations)
[ ] Names truncated to 63 characters

Template quality patterns:

# ✅ Good
metadata:
  name: {{ include "mychart.fullname" . }}
  labels:
    {{- include "mychart.labels" . | nindent 4 }}
  annotations:
    checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}

{{- if .Values.ingress.enabled }}
# ... conditional resource
{{- end }}

image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"

# Safe nil handling
{{- with .Values.tolerations }}
tolerations:
  {{- toYaml . | nindent 8 }}
{{- end }}

# ❌ Bad
name: my-app-{{ .Release.Name }}       # Hardcoded
image: {{ .Values.image }}:latest      # Hardcoded latest
{{ .Values.nested.value }}             # No nil check

Step 6: Testing Review Checklist

[ ] helm lint passes without errors or warnings
[ ] helm template renders correctly
[ ] Dry run succeeds
[ ] Unit tests exist and pass (helm-unittest)
[ ] All conditional paths tested (enabled/disabled features)
[ ] Multiple environments tested (dev, staging, prod values)

Security Scanning Integration

Kubesec Analysis

# Scan rendered templates for security issues
helm template mychart ./charts/mychart | kubesec scan -

# Look for:
# - Missing security contexts
# - Privileged containers
# - Host path mounts
# - Host network usage

Trivy Image Scanning

# Extract images from chart
helm template mychart ./charts/mychart | grep "image:" | sort -u

# Scan each image for vulnerabilities
trivy image myapp:1.0.0

Common Review Findings and Fixes

Finding: Missing Resource Limits

# ❌ Problem
containers:
  - name: app
    image: myapp:1.0

# ✅ Solution
containers:
  - name: app
    image: myapp:1.0
    resources:
      limits:
        cpu: 500m
        memory: 256Mi
      requests:
        cpu: 250m
        memory: 128Mi

Finding: Insecure Security Context

# ❌ Problem
securityContext: {}

# ✅ Solution
securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 1000
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false
  capabilities:
    drop:
    - ALL

Finding: Latest Image Tag

# ❌ Problem
image: myapp:latest

# ✅ Solution
image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"

Finding: No Liveness/Readiness Probes

# ❌ Problem
containers:
  - name: app
    image: myapp:1.0

# ✅ Solution
containers:
  - name: app
    image: myapp:1.0
    livenessProbe:
      httpGet:
        path: /healthz
        port: http
      initialDelaySeconds: 30
      periodSeconds: 10
    readinessProbe:
      httpGet:
        path: /ready
        port: http
      initialDelaySeconds: 5
      periodSeconds: 5

Review Severity Levels

BLOCKER (must fix before merge):

Hardcoded secrets
Missing security contexts
Privileged containers
No resource limits
Use of :latest tag

CRITICAL (must fix before production):

Missing liveness/readiness probes
Single replica without PDB
No pod disruption budget
Incorrect RBAC (too permissive)

MAJOR (should fix):

Undocumented values
Missing tests
Incomplete README
No CHANGELOG entry

MINOR (nice to have):

Improved comments
Additional examples
Optimization opportunities

Pre-Release Checklist

Before releasing chart:

[ ] All security review items pass
[ ] All structure review items pass
[ ] All tests pass (lint, unit, integration, dry-run)
[ ] Security scanning completed (kubesec, trivy)
[ ] Documentation updated and accurate
[ ] CHANGELOG.md updated with version notes
[ ] Version bumped appropriately (major/minor/patch)
[ ] Tested in staging environment
[ ] Rollback procedure documented
[ ] Resource quotas validated
[ ] Network policies tested
[ ] Monitoring/alerting configured

CI/CD Quality Gates

Example pipeline checks:

# GitLab CI / GitHub Actions
helm-lint:
  stage: test
  script:
    - helm lint ./charts/*

helm-unittest:
  stage: test
  script:
    - helm unittest ./charts/*

helm-security-scan:
  stage: test
  script:
    - helm template ./charts/* | kubesec scan -
    - helm template ./charts/* | trivy config -

helm-dry-run:
  stage: test
  script:
    - helm install test ./charts/mychart --dry-run --debug

Documentation Review

README.md must include:

[ ] Chart description and purpose
[ ] Prerequisites and dependencies
[ ] Installation instructions
[ ] Configuration options (values) table
[ ] Usage examples
[ ] Upgrade instructions

CHANGELOG.md must track:

[ ] Version number and date
[ ] Added features
[ ] Changed behavior
[ ] Deprecated features
[ ] Removed features
[ ] Fixed bugs
[ ] Security fixes

Resources

Related Agent

For comprehensive Helm/Kubernetes guidance that coordinates this and other Helm skills, use the helm-kubernetes-expert agent.

Agent Skills: Helm Chart Review

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