云原生架构设计

十二要素应用

要素	说明
1. 基准代码	一份代码，多次部署
2. 依赖	显式声明依赖
3. 配置	在环境中存储配置
4. 后端服务	把后端服务当作附加资源
5. 构建、发布、运行	严格分离构建和运行
6. 进程	以一个或多个无状态进程运行应用
7. 端口绑定	通过端口绑定提供服务
8. 并发	通过进程模型进行扩展
9. 易处理	快速启动和优雅终止
10. 开发/生产等价	尽可能保持开发、发布、线上环境相同
11. 日志	把日志当作事件流
12. 管理进程	后台管理任务当作一次性进程运行

配置管理

# 环境变量配置
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
        - name: myapp
          envFrom:
            - configMapRef:
                name: app-config
            - secretRef:
                name: app-secrets
          env:
            - name: NODE_ENV
              value: production

无状态设计

# 无状态应用
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: myapp:v1
          # 不挂载本地存储
          # 使用外部存储（Redis、数据库）

健康检查

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
        - name: myapp
          livenessProbe:
            httpGet:
              path: /healthz
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 5
          startupProbe:
            httpGet:
              path: /healthz
              port: 8080
            failureThreshold: 30
            periodSeconds: 10

优雅终止

# Python示例
import signal
import sys
from flask import Flask

app = Flask(__name__)

def shutdown_handler(signum, frame):
    # 完成正在处理的请求
    # 关闭数据库连接
    # 刷新日志
    sys.exit(0)

signal.signal(signal.SIGTERM, shutdown_handler)
signal.signal(signal.SIGINT, shutdown_handler)

@app.route('/healthz')
def healthz():
    return 'OK'

服务网格

# Istio服务网格
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: myapp
spec:
  hosts:
    - myapp
  http:
    - route:
        - destination:
            host: myapp
            subset: v1
          weight: 90
        - destination:
            host: myapp
            subset: v2
          weight: 10
      retries:
        attempts: 3
        perTryTimeout: 2s
      timeout: 10s

实践：云原生应用模板

# 完整的云原生应用配置
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
  labels:
    app: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  template:
    metadata:
      labels:
        app: myapp
    spec:
      serviceAccountName: myapp
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
      containers:
        - name: myapp
          image: myapp:v1
          ports:
            - containerPort: 8080
          envFrom:
            - configMapRef:
                name: myapp-config
            - secretRef:
                name: myapp-secrets
          resources:
            requests:
              cpu: 100m
              memory: 128Mi
            limits:
              cpu: 500m
              memory: 512Mi
          livenessProbe:
            httpGet:
              path: /healthz
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 5

---
apiVersion: v1
kind: Service
metadata:
  name: myapp
spec:
  selector:
    app: myapp
  ports:
    - port: 80
      targetPort: 8080

---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  minReplicas: 3
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70

最佳实践

1. 容器化一切
2. 无状态设计
3. 外部化配置
4. 健康检查
5. 可观测性
6. 自动化部署

总结

云原生架构是构建现代应用的最佳实践。遵循十二要素应用原则，可以构建可扩展、可维护、高可用的云原生应用。