# Helm Chart Scaffolding

Generate production-ready Helm charts with best practices.

## Task

You are a Helm expert. Generate complete Helm chart structure for applications.

### Steps:

1. **Ask for Information**:
   - Chart name
   - Application type (web app, API, worker, etc.)
   - Dependencies (databases, caches, etc.)

2. **Generate Chart Structure**:

```
my-app/
├── Chart.yaml
├── values.yaml
├── values-dev.yaml
├── values-staging.yaml
├── values-prod.yaml
├── templates/
│   ├── NOTES.txt
│   ├── _helpers.tpl
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── hpa.yaml
│   ├── serviceaccount.yaml
│   ├── networkpolicy.yaml
│   └── tests/
│       └── test-connection.yaml
├── charts/  # Subcharts
└── .helmignore
```

3. **Generate Chart.yaml**:

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

keywords:
  - application
  - api

home: https://github.com/myorg/my-app
sources:
  - https://github.com/myorg/my-app

maintainers:
  - name: Your Name
    email: you@example.com
    url: https://example.com

dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled
  - name: redis
    version: "17.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: redis.enabled
```

4. **Generate values.yaml**:

```yaml
# Default values for my-app
# This is a YAML-formatted file

replicaCount: 3

image:
  repository: myapp
  pullPolicy: IfNotPresent
  tag: ""  # Overrides appVersion

imagePullSecrets: []

nameOverride: ""
fullnameOverride: ""

serviceAccount:
  create: true
  annotations: {}
  name: ""

podAnnotations:
  prometheus.io/scrape: "true"
  prometheus.io/port: "8080"

podSecurityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 2000

securityContext:
  capabilities:
    drop:
    - ALL
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false

service:
  type: ClusterIP
  port: 80
  targetPort: 8080

ingress:
  enabled: true
  className: "nginx"
  annotations:
    cert-manager.io/cluster-issuer: "letsencrypt-prod"
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
          pathType: Prefix
  tls:
    - secretName: myapp-tls
      hosts:
        - myapp.example.com

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

autoscaling:
  enabled: true
  minReplicas: 3
  maxReplicas: 10
  targetCPUUtilizationPercentage: 70
  targetMemoryUtilizationPercentage: 80

nodeSelector: {}

tolerations: []

affinity:
  podAntiAffinity:
    preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 100
        podAffinityTerm:
          labelSelector:
            matchExpressions:
              - key: app.kubernetes.io/name
                operator: In
                values:
                  - my-app
          topologyKey: kubernetes.io/hostname

# Application-specific configs
config:
  logLevel: info
  nodeEnv: production

# Dependencies
postgresql:
  enabled: true
  auth:
    database: myapp
    username: myapp
  primary:
    persistence:
      enabled: true
      size: 10Gi

redis:
  enabled: true
  architecture: standalone
  auth:
    enabled: true
```

5. **Generate deployment.yaml (templated)**:

```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 }}
  selector:
    matchLabels:
      {{- include "my-app.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      annotations:
        checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
        {{- with .Values.podAnnotations }}
        {{- toYaml . | nindent 8 }}
        {{- end }}
      labels:
        {{- include "my-app.selectorLabels" . | nindent 8 }}
    spec:
      {{- with .Values.imagePullSecrets }}
      imagePullSecrets:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      serviceAccountName: {{ include "my-app.serviceAccountName" . }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
      - name: {{ .Chart.Name }}
        securityContext:
          {{- toYaml .Values.securityContext | nindent 12 }}
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
        imagePullPolicy: {{ .Values.image.pullPolicy }}
        ports:
        - name: http
          containerPort: {{ .Values.service.targetPort }}
          protocol: TCP
        livenessProbe:
          httpGet:
            path: /health
            port: http
        readinessProbe:
          httpGet:
            path: /ready
            port: http
        resources:
          {{- toYaml .Values.resources | nindent 12 }}
        env:
        - name: NODE_ENV
          value: {{ .Values.config.nodeEnv }}
        - name: LOG_LEVEL
          value: {{ .Values.config.logLevel }}
        {{- if .Values.postgresql.enabled }}
        - name: DB_HOST
          value: {{ include "my-app.fullname" . }}-postgresql
        - name: DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: {{ include "my-app.fullname" . }}-postgresql
              key: password
        {{- end }}
```

6. **Generate _helpers.tpl**:

```yaml
{{/*
Expand the name of the chart.
*/}}
{{- define "my-app.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}

{{/*
Create a default fully qualified app name.
*/}}
{{- define "my-app.fullname" -}}
{{- if .Values.fullnameOverride }}
{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- $name := default .Chart.Name .Values.nameOverride }}
{{- if contains $name .Release.Name }}
{{- .Release.Name | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}
{{- end }}

{{/*
Common labels
*/}}
{{- define "my-app.labels" -}}
helm.sh/chart: {{ include "my-app.chart" . }}
{{ include "my-app.selectorLabels" . }}
{{- if .Chart.AppVersion }}
app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
{{- end }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}

{{/*
Selector labels
*/}}
{{- define "my-app.selectorLabels" -}}
app.kubernetes.io/name: {{ include "my-app.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
{{- end }}
```

### Deployment Commands:

```bash
# Install chart
helm install my-app ./my-app -f values-dev.yaml

# Upgrade
helm upgrade my-app ./my-app -f values-prod.yaml

# Template (dry-run)
helm template my-app ./my-app -f values-prod.yaml

# Lint
helm lint ./my-app

# Package
helm package ./my-app

# Test
helm test my-app
```

### Example Usage:

```
User: "Create Helm chart for Node.js API with PostgreSQL"
Result: Complete Helm chart with all templates and values files
```