Helm Chart Review

Review Helm charts including security, quality, best practices, and code review guidelines.

Keywords

helm, chart, review, reviewing, security, quality, auditing, audit, best practices, code review, trivy, kubescape, polaris, pluto, lint, linting, validating, validation, analyzing, analysis

When to Use This Skill

• Performing code reviews of Helm charts
• Conducting security audits of charts
• Assessing chart quality and best practices
• Running automated chart analysis tools
• Validating chart structure and organization

Related Skills

• helm-chart-development - Creating charts
• helm-chart-maintenance - Maintaining charts
• k8s-security-hardening - Security best practices
• Shared: Pod Security Context
• Shared: RBAC Patterns

Quick Reference

Review Checklist

Structure & Organization

• Standard directory structure followed
• Chart.yaml has required fields (apiVersion, name, version)
• README.md exists and is complete
• NOTES.txt provides useful post-install information
• .helmignore excludes unnecessary files
• Templates organized logically

Values Design

• values.yaml has sensible defaults
• All values documented with comments
• values.schema.json validates inputs
• No hardcoded values in templates
• Sensitive values use secrets, not configmaps

Security

• Pod security context defined
• Container security context defined
• Service account with minimal permissions
• Network policies included (if applicable)
• No privileged containers by default
• Resource limits defined

Quality

• Templates pass helm lint
• Unit tests exist and pass
• Labels follow Kubernetes conventions
• Proper use of helpers (_helpers.tpl)
• Consistent naming conventions

Security Review

Pod Security Checklist

# REQUIRED security settings
podSecurityContext:
  runAsNonRoot: true       # ✓ Never run as root
  fsGroup: 1000            # ✓ Set filesystem group
  seccompProfile:
    type: RuntimeDefault   # ✓ Use seccomp

securityContext:
  allowPrivilegeEscalation: false  # ✓ Block privilege escalation
  readOnlyRootFilesystem: true     # ✓ Immutable container
  runAsNonRoot: true               # ✓ Non-root user
  runAsUser: 1000                  # ✓ Specific UID
  capabilities:
    drop:
      - ALL                        # ✓ Drop all capabilities

Security Anti-Patterns

# ❌ BAD: Privileged container
securityContext:
  privileged: true

# ❌ BAD: Running as root
securityContext:
  runAsUser: 0

# ❌ BAD: Writable root filesystem
securityContext:
  readOnlyRootFilesystem: false

# ❌ BAD: Host namespaces
hostNetwork: true
hostPID: true
hostIPC: true

# ❌ BAD: Dangerous volume mounts
volumes:
  - name: host
    hostPath:
      path: /

# ❌ BAD: Secrets in environment variables (prefer mounted secrets)
env:
  - name: DB_PASSWORD
    value: "hardcoded-password"

# ❌ BAD: No resource limits
resources: {}

RBAC Review

# ✓ GOOD: Minimal permissions
rules:
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["get", "list", "watch"]
  resourceNames: ["my-config"]  # Even better: specific resources

# ❌ BAD: Overly permissive
rules:
- apiGroups: ["*"]
  resources: ["*"]
  verbs: ["*"]

# ❌ BAD: Cluster-wide access when namespace-scoped sufficient
kind: ClusterRole  # Should be Role if namespace-scoped

Image Security

# ✓ GOOD: Specific tag
image:
  repository: myapp
  tag: "v1.2.3"  # Specific version

# ❌ BAD: Latest tag
image:
  repository: myapp
  tag: "latest"  # Mutable, unpredictable

# ✓ GOOD: Digest pinning for critical apps
image:
  repository: myapp@sha256:abc123...

Quality Review

Template Quality

# ✓ GOOD: Use helpers for common patterns
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}

# ❌ BAD: Duplicated logic
metadata:
  name: {{ .Release.Name }}-{{ .Chart.Name }}
  labels:
    app: {{ .Chart.Name }}
    release: {{ .Release.Name }}

Whitespace & Formatting

# ✓ GOOD: Proper indentation with nindent
spec:
  {{- with .Values.nodeSelector }}
  nodeSelector:
    {{- toYaml . | nindent 4 }}
  {{- end }}

# ❌ BAD: Manual indentation (error-prone)
spec:
  {{- if .Values.nodeSelector }}
  nodeSelector:
{{ toYaml .Values.nodeSelector | indent 4 }}
  {{- end }}

Conditional Resources

# ✓ GOOD: Clean conditional
{{- if .Values.ingress.enabled }}
apiVersion: networking.k8s.io/v1
kind: Ingress
...
{{- end }}

# ✓ GOOD: Required values
image: {{ required "image.repository is required" .Values.image.repository }}

# ❌ BAD: Silent failures
image: {{ .Values.image.repository }}  # Empty if not set

Labels & Annotations

# ✓ GOOD: Standard Kubernetes labels
metadata:
  labels:
    app.kubernetes.io/name: {{ include "myapp.name" . }}
    app.kubernetes.io/instance: {{ .Release.Name }}
    app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
    app.kubernetes.io/managed-by: {{ .Release.Service }}
    helm.sh/chart: {{ include "myapp.chart" . }}

# ❌ BAD: Non-standard labels
metadata:
  labels:
    app: myapp
    version: v1

Values Review

Documentation

# ✓ GOOD: Documented values
# -- Number of pod replicas
# @default -- 1
replicaCount: 1

# -- Image configuration
image:
  # -- Repository for the container image
  repository: myapp
  # -- Image pull policy
  # @default -- IfNotPresent
  pullPolicy: IfNotPresent

# ❌ BAD: Undocumented values
replicaCount: 1
image:
  repository: myapp
  pullPolicy: IfNotPresent

Defaults

# ✓ GOOD: Sensible, secure defaults
resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 100m
    memory: 128Mi

securityContext:
  runAsNonRoot: true
  readOnlyRootFilesystem: true

# ❌ BAD: No defaults for critical settings
resources: {}
securityContext: {}

Schema Validation

// ✓ GOOD: Comprehensive schema
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "required": ["image"],
  "properties": {
    "replicaCount": {
      "type": "integer",
      "minimum": 1,
      "maximum": 100
    },
    "image": {
      "type": "object",
      "required": ["repository"],
      "properties": {
        "repository": {
          "type": "string",
          "minLength": 1
        },
        "pullPolicy": {
          "type": "string",
          "enum": ["Always", "IfNotPresent", "Never"]
        }
      }
    }
  }
}

Code Review Comments

Severity Levels

Example Review Comments

🔴 **Critical: Security - Privileged Container**
The container is running as privileged which grants full host access.
```yaml
# Current
securityContext:
  privileged: true

# Suggested
securityContext:
  privileged: false
  allowPrivilegeEscalation: false

🟠 Major: Missing Resource Limits No resource limits defined. This can lead to resource starvation.

# Add to values.yaml
resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 100m
    memory: 128Mi

🟡 Minor: Use nindent instead of indent nindent handles newlines automatically and is more reliable.

# Current
{{ toYaml .Values.labels | indent 4 }}

# Suggested
{{- toYaml .Values.labels | nindent 4 }}

🔵 Suggestion: Consider using a helper This pattern is repeated in multiple templates. Consider extracting to _helpers.tpl.

## Automated Review Tools

### helm lint
```bash
# Basic linting
helm lint mychart/

# Strict mode
helm lint mychart/ --strict

# With values
helm lint mychart/ -f values-production.yaml

Trivy (Security)

# Scan chart for misconfigurations
trivy config mychart/

# JSON output
trivy config mychart/ -f json -o results.json

Kubescape

# Scan rendered templates
helm template myrelease mychart/ | kubescape scan -

# With specific framework
helm template myrelease mychart/ | kubescape scan framework nsa -

Polaris

# Scan for best practices
helm template myrelease mychart/ | polaris audit --audit-path -

Pluto (Deprecations)

# Check for deprecated APIs
helm template myrelease mychart/ | pluto detect -

Review Process

Before Review

1. Run helm lint locally
2. Run helm template to verify rendering
3. Run security scans (Trivy, Kubescape)
4. Run unit tests

During Review

1. Check structure and organization
2. Review values.yaml design
3. Audit security settings
4. Verify template quality
5. Check documentation

After Review

1. Verify all critical issues addressed
2. Re-run automated checks
3. Test deployment in dev environment
4. Approve or request changes

Review Template

## Helm Chart Review: [chart-name] v[version]

### Summary
[Brief description of changes]

### Automated Checks
- [ ] `helm lint` passes
- [ ] `helm template` renders correctly
- [ ] Unit tests pass
- [ ] Security scan clean (Trivy/Kubescape)
- [ ] No deprecated APIs (Pluto)

### Manual Review
- [ ] Chart structure follows conventions
- [ ] Values documented and have sensible defaults
- [ ] Security contexts properly configured
- [ ] Resource limits defined
- [ ] RBAC follows least privilege
- [ ] Labels follow Kubernetes conventions
- [ ] README accurate and complete

### Issues Found
| Severity | Issue | Location |
|----------|-------|----------|
| 🔴 | ... | ... |
| 🟠 | ... | ... |

### Recommendation
[ ] ✅ Approve
[ ] 🔄 Request changes
[ ] ❌ Reject