pantheon-org/helm-generator

Helm Chart Generator

Overview

Generate production-ready Helm charts with best practices built-in. Create complete charts or individual resources with standard helpers, proper templating, and automatic validation.

Official Documentation:

• Helm Docs | Chart Best Practices | Template Functions | Sprig Functions

When to Use This Skill

Use for creating/generating Helm charts and templates. For validation/linting of existing charts use devops-skills:helm-validator; for raw K8s YAML (no Helm) use k8s-generator.

Chart Generation Workflow

Stage 1: Understand Requirements

REQUIRED: Use AskUserQuestion if any of these are missing or ambiguous:

| Missing Information | Question to Ask | |---------------------|-----------------| | Image repository/tag | "What container image should be used? (e.g., nginx:1.25)" | | Service port | "What port does the application listen on?" | | Resource limits | "What CPU/memory limits should be set? (e.g., 500m CPU, 512Mi memory)" | | Probe endpoints | "What health check endpoints does the app expose? (e.g., /health, /ready)" | | Scaling requirements | "Should autoscaling be enabled? If yes, min/max replicas and target CPU%?" | | Workload type | "What workload type: Deployment, StatefulSet, or DaemonSet?" | | Storage requirements | "Does the application need persistent storage? Size and access mode?" |

Do NOT assume values for critical settings. Ask first, then proceed.

Stage 2: CRD Documentation Lookup

If custom resources are needed:

1. Try context7 MCP first:

   mcp__context7__resolve-library-id with operator name
   mcp__context7__get-library-docs with topic for CRD kind
   

2. Fallback to WebSearch:

   "<operator>" "<CRD-kind>" "<version>" kubernetes documentation spec
   

See references/crd_patterns.md for common CRD examples.

Stage 3: Create Chart Structure

Use the scaffolding script:

bash scripts/generate_chart_structure.sh <chart-name> <output-directory> [options]

Script options:

• --image <repo> - Image repository (default: nginx). Note: Pass only the repository name without tag (e.g., redis not redis:7-alpine)
• --port <number> - Service port (default: 80)
• --type <type> - Workload type: deployment, statefulset, daemonset (default: deployment)
• --with-templates - Generate resource templates (deployment.yaml, service.yaml, etc.)
• --with-ingress - Include ingress template
• --with-hpa - Include HPA template
• --force - Overwrite existing chart without prompting

Important customization notes:

• The script uses http as the default port name in templates. Customize port names for non-HTTP services (e.g., redis, mysql, grpc)
• Templates include checksum annotations for ConfigMap/Secret changes (conditionally enabled via .Values.configMap.enabled and .Values.secret.enabled)

Stage 4: Generate Standard Helpers

Use the helpers script or assets/_helpers-template.tpl:

bash scripts/generate_standard_helpers.sh <chart-name> <chart-directory>

Stage 5: Generate Templates

⚠️ CRITICAL REQUIREMENT: Read Reference Files NOW

You MUST use the Read tool to load these reference files at this stage, even if you read them earlier in the conversation:

1. Read references/resource_templates.md - for the specific resource type patterns
2. Read references/helm_template_functions.md - for template function usage
3. Read references/crd_patterns.md - if generating CRD resources (ServiceMonitor, Certificate, etc.)

Why: Prior context may be incomplete or summarized. Reading reference files at generation time guarantees all patterns, functions, and examples are available for accurate template creation.

Do NOT skip this step. Template quality depends on having current reference patterns loaded.

Reference templates for all resource types in references/resource_templates.md:

• Workloads: Deployment, StatefulSet, DaemonSet, Job, CronJob
• Services: Service, Ingress
• Config: ConfigMap, Secret
• RBAC: ServiceAccount, Role, RoleBinding, ClusterRole, ClusterRoleBinding
• Network: NetworkPolicy
• Autoscaling: HPA, PodDisruptionBudget

Key patterns (MUST include in all templates):

# Use helpers for names and labels
metadata:
  name: {{ include "mychart.fullname" . }}
  labels: {{- include "mychart.labels" . | nindent 4 }}

# Conditional sections with 'with'
{{- with .Values.nodeSelector }}
nodeSelector: {{- toYaml . | nindent 2 }}
{{- end }}

# Checksum annotation (REQUIRED for Deployments/StatefulSets/DaemonSets to trigger restarts on config changes)
annotations:
  checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}

Stage 6: Create values.yaml

Structure guidelines:

• Group related settings logically
• Document every value with # -- comments
• Provide sensible defaults
• Include security contexts, resource limits, probes

See assets/values-schema-template.json for JSON Schema validation.

Stage 7: Validate

Run validation using devops-skills:helm-validator skill (helm lint, template render, schema checks, dry-run).

Template Functions Quick Reference

See references/helm_template_functions.md for complete guide.

| Function | Purpose | Example | |----------|---------|---------| | required | Enforce required values | {{ required "msg" .Values.x }} | | default | Fallback value | {{ .Values.x \| default 1 }} | | quote | Quote strings | {{ .Values.x \| quote }} | | include | Use helpers | {{ include "name" . \| nindent 4 }} | | toYaml | Convert to YAML | {{ toYaml .Values.x \| nindent 2 }} | | tpl | Render as template | {{ tpl .Values.config . }} | | nindent | Newline + indent | {{- include "x" . \| nindent 4 }} |

Working with CRDs

See references/crd_patterns.md for complete examples. Ship CRDs in crds/ directory (not templated); template CR instances in templates/.

Converting Manifests to Helm

1. Parameterize names (use helpers) and extract values
2. Apply label/conditional patterns, use toYaml for complex objects
3. Create _helpers.tpl with standard helpers
4. Validate with devops-skills:helm-validator

Error Handling

| Issue | Solution | |-------|----------| | Template syntax errors | Check {{- / -}} matching, use helm template --debug | | Undefined values | Use default or required functions | | Indentation issues | Use nindent consistently | | CRD validation fails | Verify apiVersion, check docs for required fields |

Post-Generation Validation

After generating charts, invoke devops-skills:helm-validator to ensure quality.

Anti-Patterns

NEVER hardcode image tags in values.yaml

• WHY: Pinning to :latest or a hard-coded version in the chart prevents version overrides at deploy time.
• BAD: image: repository: myapp tag: latest
• GOOD: image: repository: myapp tag: "" with appVersion as the default, overridden via --set image.tag=v1.2.3.

NEVER omit resources: limits and requests on containers

• WHY: Containers without resource constraints are evicted unpredictably under node pressure and cannot be scheduled by the Kubernetes cluster autoscaler.
• BAD: No resources: block in the container spec template.
• GOOD: Set both requests and limits for CPU and memory, with documented tuning guidance in values.yaml.

NEVER use helm upgrade --install without --atomic in CI/CD

• WHY: Without --atomic, a failed upgrade leaves the release in a broken state that blocks future upgrades and requires manual helm rollback.
• BAD: helm upgrade --install myapp ./chart
• GOOD: helm upgrade --install --atomic --timeout 5m myapp ./chart

NEVER place environment-specific values inside the chart's default values.yaml

• WHY: Mixing production values into the chart couples the chart to one environment.
• BAD: Production database URLs in values.yaml.
• GOOD: Use a layered values approach: values.yaml for defaults, values-prod.yaml for overrides, -f values-prod.yaml at deploy time.

NEVER skip helm template + kubeval/kubeconform validation

• WHY: A chart that renders without error can still produce invalid Kubernetes manifests.
• BAD: Only run helm lint before deploying.
• GOOD: helm template . | kubeval --strict --ignore-missing-schemas to validate rendered manifests against the Kubernetes API schema.

References

Scripts

| Script | Usage | |--------|-------| | scripts/generate_chart_structure.sh | bash <script> <chart-name> <output-dir> | | scripts/generate_standard_helpers.sh | bash <script> <chart-name> <chart-dir> |

References

| File | Content | |------|---------| | references/helm_template_functions.md | Complete template function guide | | references/resource_templates.md | All K8s resource templates | | references/crd_patterns.md | CRD patterns (cert-manager, Prometheus, Istio, ArgoCD) |

Assets

| File | Purpose | |------|---------| | assets/_helpers-template.tpl | Standard helpers template | | assets/values-schema-template.json | JSON Schema for values validation |