How to Create a Helm Chart: Step-by-Step Example with phpMyAdmin & MySQL

# ติดตั้ง Helm และ minikube
brew install helm minikube kubectl

# เริ่มต้น minikube
minikube start

# ตรวจสอบการติดตั้ง
helm version
kubectl cluster-info

# Linux (Ubuntu/Debian)
curl https://baltocdn.com/helm/signing.asc | gpg --dearmor | sudo tee /usr/share/keyrings/helm.gpg > /dev/null
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/helm.gpg] https://baltocdn.com/helm/stable/debian/ all main" | sudo tee /etc/apt/sources.list.d/helm-stable-debian.list
sudo apt-get update
sudo apt-get install helm

# Windows (ใช้ Chocolatey)
choco install kubernetes-helm minikube

helm create my-example-chart
cd my-example-chart

my-example-chart/
├── Chart.yaml          # ข้อมูล metadata ของ chart
├── charts/             # directory สำหรับ dependencies
├── templates/          # Kubernetes manifest templates
│   ├── NOTES.txt       # ข้อความแสดงหลังการติดตั้ง
│   ├── _helpers.tpl    # template helpers และ functions
│   ├── deployment.yaml # deployment template
│   ├── hpa.yaml        # horizontal pod autoscaler
│   ├── ingress.yaml    # ingress template
│   ├── service.yaml    # service template
│   ├── serviceaccount.yaml # service account template
│   └── tests/
│       └── test-connection.yaml # connection test
└── values.yaml         # default values สำหรับ templates

apiVersion: v2
name: my-example-chart
version: 0.0.1
description: my chart for test phpmyadmin connect to mysql
type: application

appVersion: "5.2.0"

dependencies:
  - name: mysql
    version: "9.19.1"
    repository: oci://registry-1.docker.io/bitnamicharts

maintainers:
- name: trwkc
  url: https://github.com/trwkc

helm dep build

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Values.name }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Values.name }}
  template:
    metadata:
      labels:
        app: {{ .Values.name }}
        release: {{ .Release.Name }}
    spec:
      containers:
        - name: {{ .Values.name }}
          image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
          - containerPort: {{ .Values.service.port }}
          env:
            - name: PMA_HOST
              value: {{ .Release.Name }}-mysql
            - name: MYSQL_ROOT_PASSWORD
              value: {{ .Values.mysql.auth.rootPassword }}

apiVersion: v1
kind: Service
metadata:
  name: {{ .Values.name }}
  labels:
    app: {{ .Values.name }}
    release: {{ .Release.Name }}
spec:
  type: {{ .Values.service.type }}
  ports:
    - port: 80
      targetPort: 80
  selector:
    app: {{ .Values.name }}

name: my-example
replicaCount: 1

image:
  repository: phpmyadmin
  pullPolicy: IfNotPresent
  tag: "5.2.0"

service:
  type: ClusterIP
  port: 80

mysql:
  auth:
    rootPassword: pass12345

helm install --debug my-example .

helm upgrade --reuse-values --set image.tag=5.2.1 --debug my-example .

helm uninstall my-example

# Chart.yaml
apiVersion: v2
name: my-app  # ใช้ชื่อที่ชัดเจนและสั้น
version: 1.0.0  # ใช้ semantic versioning
appVersion: "2.1.4"  # version ของ application

# values.yaml - จัดกลุ่มและเพิ่ม comments
# Application settings
app:
  name: my-app
  version: "2.1.4"
  
# Container settings  
image:
  repository: nginx
  tag: "1.21"
  pullPolicy: IfNotPresent

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

# ใช้ labels และ selectors ที่สอดคล้องกัน
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "chart.fullname" . }}
  labels:
    {{- include "chart.labels" . | nindent 4 }}
spec:
  selector:
    matchLabels:
      {{- include "chart.selectorLabels" . | nindent 6 }}

# ใช้ Security Context
securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 2000

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

# ทดสอบ template rendering
helm template my-example .

# ทดสอบ values
helm lint .

# dry-run ก่อนติดตั้งจริง
helm install --dry-run --debug my-example .