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Zhongwei Li
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commands/helm-scaffold.md
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333
commands/helm-scaffold.md
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# Helm Chart Scaffolding
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Generate production-ready Helm charts with best practices.
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## Task
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You are a Helm expert. Generate complete Helm chart structure for applications.
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### Steps:
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1. **Ask for Information**:
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- Chart name
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- Application type (web app, API, worker, etc.)
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- Dependencies (databases, caches, etc.)
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2. **Generate Chart Structure**:
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```
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my-app/
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├── Chart.yaml
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├── values.yaml
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├── values-dev.yaml
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├── values-staging.yaml
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├── values-prod.yaml
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├── templates/
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│ ├── NOTES.txt
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│ ├── _helpers.tpl
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│ ├── deployment.yaml
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│ ├── service.yaml
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│ ├── ingress.yaml
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│ ├── configmap.yaml
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│ ├── secret.yaml
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│ ├── hpa.yaml
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│ ├── serviceaccount.yaml
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│ ├── networkpolicy.yaml
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│ └── tests/
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│ └── test-connection.yaml
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├── charts/ # Subcharts
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└── .helmignore
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```
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3. **Generate Chart.yaml**:
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```yaml
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apiVersion: v2
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name: my-app
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description: A Helm chart for my-app
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type: application
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version: 1.0.0 # Chart version
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appVersion: "1.0.0" # Application version
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keywords:
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- application
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- api
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home: https://github.com/myorg/my-app
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sources:
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- https://github.com/myorg/my-app
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maintainers:
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- name: Your Name
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email: you@example.com
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url: https://example.com
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dependencies:
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- name: postgresql
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version: "12.x.x"
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repository: https://charts.bitnami.com/bitnami
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condition: postgresql.enabled
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- name: redis
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version: "17.x.x"
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repository: https://charts.bitnami.com/bitnami
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condition: redis.enabled
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```
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4. **Generate values.yaml**:
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```yaml
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# Default values for my-app
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# This is a YAML-formatted file
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replicaCount: 3
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image:
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repository: myapp
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pullPolicy: IfNotPresent
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tag: "" # Overrides appVersion
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imagePullSecrets: []
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nameOverride: ""
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fullnameOverride: ""
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serviceAccount:
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create: true
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annotations: {}
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name: ""
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podAnnotations:
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prometheus.io/scrape: "true"
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prometheus.io/port: "8080"
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podSecurityContext:
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runAsNonRoot: true
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runAsUser: 1000
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fsGroup: 2000
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securityContext:
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capabilities:
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drop:
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- ALL
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readOnlyRootFilesystem: true
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allowPrivilegeEscalation: false
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service:
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type: ClusterIP
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port: 80
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targetPort: 8080
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ingress:
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enabled: true
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className: "nginx"
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annotations:
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cert-manager.io/cluster-issuer: "letsencrypt-prod"
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hosts:
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- host: myapp.example.com
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paths:
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- path: /
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pathType: Prefix
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tls:
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- secretName: myapp-tls
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hosts:
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- myapp.example.com
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resources:
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limits:
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cpu: 500m
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memory: 512Mi
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requests:
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cpu: 250m
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memory: 256Mi
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autoscaling:
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enabled: true
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minReplicas: 3
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maxReplicas: 10
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targetCPUUtilizationPercentage: 70
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targetMemoryUtilizationPercentage: 80
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nodeSelector: {}
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tolerations: []
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affinity:
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podAntiAffinity:
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preferredDuringSchedulingIgnoredDuringExecution:
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- weight: 100
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podAffinityTerm:
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labelSelector:
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matchExpressions:
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- key: app.kubernetes.io/name
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operator: In
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values:
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- my-app
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topologyKey: kubernetes.io/hostname
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# Application-specific configs
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config:
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logLevel: info
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nodeEnv: production
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# Dependencies
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postgresql:
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enabled: true
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auth:
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database: myapp
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username: myapp
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primary:
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persistence:
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enabled: true
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size: 10Gi
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redis:
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enabled: true
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architecture: standalone
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auth:
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enabled: true
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```
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5. **Generate deployment.yaml (templated)**:
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: {{ include "my-app.fullname" . }}
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labels:
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{{- include "my-app.labels" . | nindent 4 }}
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spec:
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{{- if not .Values.autoscaling.enabled }}
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replicas: {{ .Values.replicaCount }}
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{{- end }}
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selector:
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matchLabels:
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{{- include "my-app.selectorLabels" . | nindent 6 }}
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template:
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metadata:
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annotations:
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checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
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{{- with .Values.podAnnotations }}
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{{- toYaml . | nindent 8 }}
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{{- end }}
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labels:
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{{- include "my-app.selectorLabels" . | nindent 8 }}
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spec:
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{{- with .Values.imagePullSecrets }}
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imagePullSecrets:
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{{- toYaml . | nindent 8 }}
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{{- end }}
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serviceAccountName: {{ include "my-app.serviceAccountName" . }}
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securityContext:
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{{- toYaml .Values.podSecurityContext | nindent 8 }}
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containers:
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- name: {{ .Chart.Name }}
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securityContext:
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{{- toYaml .Values.securityContext | nindent 12 }}
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image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
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imagePullPolicy: {{ .Values.image.pullPolicy }}
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ports:
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- name: http
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containerPort: {{ .Values.service.targetPort }}
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protocol: TCP
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livenessProbe:
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httpGet:
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path: /health
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port: http
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readinessProbe:
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httpGet:
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path: /ready
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port: http
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resources:
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{{- toYaml .Values.resources | nindent 12 }}
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env:
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- name: NODE_ENV
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value: {{ .Values.config.nodeEnv }}
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- name: LOG_LEVEL
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value: {{ .Values.config.logLevel }}
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{{- if .Values.postgresql.enabled }}
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- name: DB_HOST
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value: {{ include "my-app.fullname" . }}-postgresql
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- name: DB_PASSWORD
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valueFrom:
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secretKeyRef:
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name: {{ include "my-app.fullname" . }}-postgresql
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key: password
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{{- end }}
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```
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6. **Generate _helpers.tpl**:
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```yaml
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{{/*
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Expand the name of the chart.
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*/}}
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{{- define "my-app.name" -}}
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{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
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{{- end }}
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{{/*
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Create a default fully qualified app name.
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*/}}
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{{- define "my-app.fullname" -}}
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{{- if .Values.fullnameOverride }}
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{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
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{{- else }}
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{{- $name := default .Chart.Name .Values.nameOverride }}
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{{- if contains $name .Release.Name }}
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{{- .Release.Name | trunc 63 | trimSuffix "-" }}
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{{- else }}
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{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
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{{- end }}
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{{- end }}
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{{- end }}
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{{/*
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Common labels
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*/}}
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{{- define "my-app.labels" -}}
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helm.sh/chart: {{ include "my-app.chart" . }}
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{{ include "my-app.selectorLabels" . }}
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{{- if .Chart.AppVersion }}
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app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
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{{- end }}
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app.kubernetes.io/managed-by: {{ .Release.Service }}
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{{- end }}
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{{/*
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Selector labels
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*/}}
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{{- define "my-app.selectorLabels" -}}
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app.kubernetes.io/name: {{ include "my-app.name" . }}
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app.kubernetes.io/instance: {{ .Release.Name }}
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{{- end }}
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```
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### Deployment Commands:
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```bash
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# Install chart
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helm install my-app ./my-app -f values-dev.yaml
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# Upgrade
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helm upgrade my-app ./my-app -f values-prod.yaml
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# Template (dry-run)
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helm template my-app ./my-app -f values-prod.yaml
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# Lint
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helm lint ./my-app
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# Package
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helm package ./my-app
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# Test
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helm test my-app
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```
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### Example Usage:
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```
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User: "Create Helm chart for Node.js API with PostgreSQL"
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Result: Complete Helm chart with all templates and values files
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```
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Reference in New Issue
Block a user