🚀 微服務部署：Kubernetes 與 CI/CD

📌 Kubernetes 基礎概念

Kubernetes (K8s) 核心元件：
├── Pod：最小部署單位，包含一個或多個容器
├── Service：穩定的網路端點，負載平衡到 Pod
├── Deployment：管理 Pod 的副本數量和更新策略
├── ConfigMap / Secret：外部化設定
├── Ingress：外部流量的入口（類似 API Gateway）
└── Namespace：邏輯隔離（dev、staging、production）

K8s 架構圖：
┌─────────────────────────────────────────┐
│ Kubernetes Cluster                       │
│                                         │
│  ┌─────────────┐  ┌─────────────┐       │
│  │  Ingress    │  │  Ingress    │       │
│  │  (外部入口)  │  │  Controller │       │
│  └──────┬──────┘  └─────────────┘       │
│         │                               │
│  ┌──────┴──────┐                        │
│  │   Service    │ ← 負載平衡             │
│  └──────┬──────┘                        │
│         │                               │
│  ┌──────┴───────┬──────────┐            │
│  │   Pod 1     │  Pod 2   │  Pod 3     │
│  │ OrderSvc    │ OrderSvc │ OrderSvc   │
│  └─────────────┴──────────┴────────┘    │
└─────────────────────────────────────────┘

📌 將 .NET 微服務部署到 K8s

Deployment 設定

# k8s/product-service/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: product-service
  namespace: eshop
  labels:
    app: product-service
spec:
  replicas: 3
  selector:
    matchLabels:
      app: product-service
  template:
    metadata:
      labels:
        app: product-service
    spec:
      containers:
        - name: product-service
          image: myregistry.azurecr.io/product-service:v1.0.0
          ports:
            - containerPort: 8080
          env:
            - name: ASPNETCORE_ENVIRONMENT
              value: "Production"
            - name: ConnectionStrings__DefaultConnection
              valueFrom:
                secretKeyRef:
                  name: product-db-secret
                  key: connection-string
          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "500m"
              memory: "512Mi"
          livenessProbe:
            httpGet:
              path: /health/live
              port: 8080
            initialDelaySeconds: 15
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /health/ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 5
          startupProbe:
            httpGet:
              path: /health/live
              port: 8080
            failureThreshold: 30
            periodSeconds: 10

Service 設定

# k8s/product-service/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: product-service
  namespace: eshop
spec:
  selector:
    app: product-service
  ports:
    - port: 80
      targetPort: 8080
  type: ClusterIP

Ingress 設定

# k8s/ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: eshop-ingress
  namespace: eshop
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  ingressClassName: nginx
  rules:
    - host: api.eshop.example.com
      http:
        paths:
          - path: /products(/|$)(.*)
            pathType: ImplementationSpecific
            backend:
              service:
                name: product-service
                port:
                  number: 80
          - path: /orders(/|$)(.*)
            pathType: ImplementationSpecific
            backend:
              service:
                name: order-service
                port:
                  number: 80

📌 Helm Charts 管理

Helm 是 Kubernetes 的套件管理工具，用模板化的方式管理 K8s 資源。

# helm/product-service/values.yaml
replicaCount: 3

image:
  repository: myregistry.azurecr.io/product-service
  tag: "v1.0.0"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

resources:
  requests:
    cpu: 100m
    memory: 128Mi
  limits:
    cpu: 500m
    memory: 512Mi

autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 70

# helm/product-service/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "product-service.fullname" . }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ include "product-service.name" . }}
  template:
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

# Helm 常用指令
helm install product-service ./helm/product-service -n eshop
helm upgrade product-service ./helm/product-service -n eshop
helm rollback product-service 1 -n eshop  # 回滾到版本 1
helm list -n eshop                         # 列出所有部署

📌 CI/CD Pipeline（GitHub Actions）

# .github/workflows/deploy-product-service.yml
name: Deploy Product Service

on:
  push:
    branches: [main]
    paths:
      - 'src/ProductService/**'

env:
  REGISTRY: myregistry.azurecr.io
  IMAGE_NAME: product-service

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '8.0.x'

      - name: Run Tests
        run: |
          cd src/ProductService
          dotnet test --configuration Release

      - name: Build Docker Image
        run: |
          docker build -t $REGISTRY/$IMAGE_NAME:${{ github.sha }} \
            -t $REGISTRY/$IMAGE_NAME:latest \
            ./src/ProductService

      - name: Login to Container Registry
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ secrets.ACR_USERNAME }}
          password: ${{ secrets.ACR_PASSWORD }}

      - name: Push Docker Image
        run: |
          docker push $REGISTRY/$IMAGE_NAME:${{ github.sha }}
          docker push $REGISTRY/$IMAGE_NAME:latest

      - name: Deploy to Kubernetes
        uses: azure/k8s-deploy@v5
        with:
          namespace: eshop
          manifests: k8s/product-service/
          images: |
            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}

📌 藍綠部署 / 金絲雀發布

金絲雀發布（Canary Deployment）

# 先部署少量新版本 Pod 測試
apiVersion: apps/v1
kind: Deployment
metadata:
  name: product-service-canary
spec:
  replicas: 1  # 只部署 1 個新版本 Pod
  selector:
    matchLabels:
      app: product-service
      version: canary
  template:
    metadata:
      labels:
        app: product-service
        version: canary
    spec:
      containers:
        - name: product-service
          image: myregistry.azurecr.io/product-service:v2.0.0-rc1

// 在 .NET 中配合 Feature Flags 控制流量
builder.Services.AddFeatureManagement()
    .AddFeatureFilter<PercentageFilter>();

// appsettings.json
// "FeatureManagement": {
//   "NewCheckoutFlow": {
//     "EnabledFor": [{
//       "Name": "Percentage",
//       "Parameters": { "Value": 10 }  // 10% 流量使用新版
//     }]
//   }
// }

📌 Service Mesh 概念

Dapr（分散式應用執行環境）

// 使用 Dapr 簡化微服務開發
// 不需要直接依賴 RabbitMQ、Redis 等具體技術

// 透過 Dapr 呼叫其他服務
app.MapGet("/api/orders/{id}", async (int id, DaprClient dapr) =>
{
    // Dapr 自動處理服務發現和負載平衡
    var product = await dapr.InvokeMethodAsync<ProductDto>(
        HttpMethod.Get,
        "product-service",  // 服務名稱，不需要知道 IP/Port
        $"api/products/{id}");

    return Results.Ok(product);
});

// 透過 Dapr 發布事件
app.MapPost("/api/orders", async (CreateOrderDto dto, DaprClient dapr) =>
{
    var order = CreateOrder(dto);

    // Dapr 抽象了 Message Broker（RabbitMQ、Kafka、Azure Service Bus...）
    await dapr.PublishEventAsync(
        "pubsub",           // Pub/Sub 組件名稱
        "order-created",    // Topic 名稱
        new OrderCreatedEvent(order.Id, order.Items));

    return Results.Created($"/api/orders/{order.Id}", order);
});

📌 從程式碼到部署的全流程總結

完整的微服務開發到部署流程：

1. 設計階段
   └── DDD 分析 → 定義 Bounded Context → 劃分服務

2. 開發階段
   ├── 建立 ASP.NET Core API
   ├── 實作業務邏輯
   ├── 撰寫單元測試與整合測試
   └── 設定韌性策略（Polly）

3. 容器化
   ├── 撰寫 Dockerfile
   ├── 建立 docker-compose.yml
   └── 本地測試所有服務

4. 可觀測性
   ├── 設定 Serilog + Seq
   ├── 設定 OpenTelemetry + Jaeger
   └── 設定 Prometheus + Grafana

5. 部署
   ├── 建立 K8s manifests / Helm Charts
   ├── 設定 CI/CD Pipeline
   ├── 金絲雀發布
   └── 監控與告警

Done! 🎉 你已經完成了微服務架構的完整學習路線！

恭喜完成！ 你已經學會了從微服務設計到 Kubernetes 部署的所有核心知識。建議從小型專案開始實踐，逐步累積經驗。