helm-chart-scaffolding

SKILL.md 节选

# Helm Chart Scaffolding

Comprehensive guidance for creating, organizing, and managing Helm charts for packaging and deploying Kubernetes applications.

## Purpose

This skill provides step-by-step instructions for building production-ready Helm charts, including chart structure, templating patterns, values management, and validation strategies.

## When to Use This Skill

Use this skill when you need to:
- Create new Helm charts from scratch
- Package Kubernetes applications for distribution
- Manage multi-environment deployments with Helm
- Implement templating for reusable Kubernetes manifests
- Set up Helm chart repositories
- Follow Helm best practices and conventions

## Helm Overview

**Helm** is the package manager for Kubernetes that:
- Templates Kubernetes manifests for reusability
- Manages application releases and rollbacks
- Handles dependencies between charts
- Provides version control for deployments
- Simplifies configuration management across environments

## Step-by-Step Workflow

### 1. Initialize Chart Structure

**Create new chart:**
```bash
helm create my-app
```

**Standard chart structure:**
```
my-app/
├── Chart.yaml           # Chart metadata
├── values.yaml          # Default configuration values
├── charts/              # Chart dependencies
├── templates/           # Kubernetes manifest templates
│   ├── NOTES.txt       # Post-install notes
│   ├── _helpers.tpl    # Template helpers
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── serviceaccount.yaml
│   ├── hpa.yaml
│   └── tests/
│       └── test-connection.yaml
└── .helmignore         # Files to ignore
```

### 2. Configure Chart.yaml

**Chart metadata defines the package:**

```yaml
apiVersion: v2
name: my-app
description: A Helm chart for My Application
type: application
version: 1.0.0      # Chart version
appVersion: "2.1.0" # Application version

# Keywords for chart discovery
keywords:
  - web
  - api
  - backend

# Maintainer information
maintainers:
  - name: DevOps Team
    email: devops@example.com
    url: https://github.com/example/my-app

# Source code repository
sources:
  - https://github.com/example/my-app

# Homepage
home: https://example.com

# Chart icon
icon: https://example.com/icon.png

# Dependencies
dependencies:
  - name: postgresql
    version: "12.0.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled
  - name: redis
    version: "17.0.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: redis.enabled
```

**Reference:** See `assets/Chart.yaml.template` for complete example

### 3. Design values.yaml Structure

**Organize values hierarchically:**

```yaml
# Image configuration
image:
  repository: myapp
  tag: "1.0.0"
  pullPolicy: IfNotPresent

# Number of replicas
replicaCount: 3

# Service configuration
service:
  type: ClusterIP
  port: 80
  targetPort: 8080

# Ingress configuration
ingress:
  enabled: false
  className: nginx
  hosts:
    - host: app.example.com
      paths:
        - path: /
          pathType: Prefix

# Resources
resources:
  requests:
    memory: "256Mi"
    cpu: "250m"
  limits:
    memory: "512Mi"
    cpu: "500m"

# Autoscaling
autoscaling:
  enabled: false
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

# Environment variables
env:
  - name: LOG_LEVEL
    value: "info"

# ConfigMap data
configMap:
  data:
    APP_MODE: production

# Dependencies
postgresql:
  enabled: true
  auth:
    database: myapp
    username: myapp

redis:
  enabled: false
```

**Reference:** See `assets/values.yaml.template` for complete structure

### 4. Create Template Files

**Use Go templating with Helm functions:**

**templates/deployment.yaml:**
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "my-app.fullname" . }}
  labels:
    {{- include "my-app.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}

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