helm-generator

What this skill does

# Helm Chart Generator

## Overview

Generate production-ready Helm charts with deterministic scaffolding, standard helpers, reusable templates, and validation loops.

**Official Documentation:**
- [Helm Docs](https://helm.sh/docs/) - Main documentation
- [Chart Best Practices](https://helm.sh/docs/chart_best_practices/) - Official best practices guide
- [Template Functions](https://helm.sh/docs/chart_template_guide/function_list/) - Built-in functions
- [Sprig Functions](http://masterminds.github.io/sprig/) - Extended function library

## When to Use This Skill

| Use helm-generator | Use OTHER skill |
|-------------------|-----------------|
| Create new Helm charts | **helm-validator**: Validate/lint existing charts |
| Generate Helm templates | **k8s-yaml-generator**: Raw K8s YAML (no Helm) |
| Convert K8s manifests to Helm | **k8s-debug**: Debug deployed resources |
| Implement CRDs in Helm | **k8s-yaml-validator**: Validate K8s manifests |

### Trigger Phrases

Use this skill when prompts include phrases like:
- "create Helm chart"
- "scaffold Helm chart"
- "generate Helm templates"
- "convert manifests to Helm chart"
- "build chart with Deployment/Service/Ingress"

## Execution Flow

Follow these stages in order. Do not skip required stages.

### Stage 1: Gather Requirements (Required)

Collect:
- Scope: full chart, specific templates, or conversion from manifests
- Workload: `deployment`, `statefulset`, or `daemonset`
- Image reference: repository, optional tag, or digest
- Ports: service port and container target port (separate values)
- Runtime settings: resources, probes, autoscaling, ingress, storage
- Security: service account, security contexts, optional RBAC/network policies

Use `request_user_input` when critical fields are missing.

If `request_user_input` is unavailable, ask in normal chat and continue with explicit assumptions.

| Missing Information | Question to Ask |
|---------------------|-----------------|
| Image repository/tag | "What container image should be used? (e.g., nginx:1.25)" |
| Service port | "What service port should be exposed?" |
| Container target port | "What container port should traffic be forwarded to?" |
| 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 silently assume critical settings.

### Stage 2: Lookup CRD Documentation (Only if CRDs Are In Scope)

1. Try Context7 first:
   - `mcp__context7__resolve-library-id`
   - `mcp__context7__query-docs`
2. Fallback chain if Context7 is unavailable or incomplete:
   - Operator official docs (preferred)
   - General web search

Also consult `references/crd_patterns.md` for example patterns.

### Stage 3: Scaffold Chart Structure (Required)

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

Options:
- `--image <repo>` - Supports repo-only, tagged image, registry ports, and digest refs
- `--port <number>` - Service port (default: 80)
- `--target-port <number>` - Container target port (default: 8080)
- `--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

Image parsing behavior:
- `--image nginx:1.27` -> repository `nginx`, tag `1.27`
- `--image registry.local:5000/team/app` -> repository kept intact
- `--image ghcr.io/org/app@sha256:...` -> digest mode (no tag concatenation)
- `--tag` cannot be combined with digest image references

Idempotency and overwrite behavior:
- `generate_chart_structure.sh`: prompts before overwrite; `--force` overwrites non-interactively.
- `generate_standard_helpers.sh`: prompts before replacing `templates/_helpers.tpl`; `--force` bypasses prompt.

Expected scaffold shape:
```
mychart/
  Chart.yaml
  values.yaml
  templates/
    _helpers.tpl
    NOTES.txt
    serviceaccount.yaml
    service.yaml
    configmap.yaml
    secret.yaml
    deployment.yaml|statefulset.yaml|daemonset.yaml
    ingress.yaml (optional)
    hpa.yaml (optional)
  .helmignore
```

### Stage 4: Generate Standard Helpers

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

Required helpers: `name`, `fullname`, `chart`, `labels`, `selectorLabels`, `serviceAccountName`.

Fallback:
- If script execution is blocked, copy `assets/_helpers-template.tpl` and replace `CHARTNAME` with the chart name.

### Stage 5: Consult References and Generate Templates (Required)

Consult relevant references once at this stage:
- `references/resource_templates.md` for the resource patterns being generated
- `references/helm_template_functions.md` for templating function usage
- `references/crd_patterns.md` only when CRDs are in scope

Example file-open commands:
```bash
sed -n '1,220p' references/resource_templates.md
sed -n '1,220p' references/helm_template_functions.md
```

Resource coverage from `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

Required template patterns:
```yaml
metadata:
  name: {{ include "mychart.fullname" . }}
  labels: {{- include "mychart.labels" . | nindent 4 }}

{{- with .Values.nodeSelector }}
nodeSelector: {{- toYaml . | nindent 2 }}
{{- end }}

annotations:
  {{- if and .Values.configMap .Values.configMap.enabled }}
  checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
  {{- end }}
```

Checksum annotations are required for workloads, but must be conditional and only reference generated templates (`configmap.yaml`, `secret.yaml`).

### 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
- Keep `service.port` and `service.targetPort` separate and explicit
- Keep `configMap.enabled` / `secret.enabled` aligned with generated templates

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

### Stage 7: Validate

Preferred path: run the `helm-validator` skill.

If skill invocation is unavailable, run local commands directly:
```bash
helm lint <chart-dir>
helm template test <chart-dir>
```

If `helm` is unavailable, report the block clearly and perform partial checks:
- `bash -n scripts/generate_chart_structure.sh`
- `bash -n scripts/generate_standard_helpers.sh`
- Verify generated files and key fields manually

Re-run validation after any fixes.

## 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.

Key points:
- CRDs you ship -> `crds/` directory (not templated, not deleted on uninstall)