mysql - 为什么我的externalName类型服务配置在Kubernetes中不起作用？

Question

我在每个 namespace 中创建了两个 namespace 和服务:

命名空间:应用程序层

rest-app

数据库服务外部名称

命名空间:数据层

数据库服务

当我尝试从rest-app连接到DB Service中的MySQL数据库时，出现错误:

MySql.Data.MySqlClient.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts. ---> System.AggregateException: One or more errors occurred. (Name or service not known)

我在日志中打印了出来，它正确地将db-service作为服务名称，并且具有正确的用户/密码。
这是我定义的:
数据库服务

apiVersion: v1
kind: Service
metadata:
  name: db-service
  namespace: data-layer
spec:
  selector:
    app: db-service
  ports:
   - port: 3306
  clusterIP: None

数据库服务外部名称

apiVersion: v1
kind: Service
metadata:
  name: db-service
  namespace: app-layer
spec:
  type: ExternalName
  externalName: db-service.data-layer.service.cluster.local
  ports:
    - port: 3306

rest-app

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rest-app
  namespace: app-layer
  labels:
    app: rest-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: rest-app
  template:
    metadata:
      labels:
        app: rest-app
    spec:
      containers:
        - name: rest-app
          image: restapp:latest
          imagePullPolicy: Always
          ports:
            - containerPort: 5000
          env:
            # These are from a secret I defined, and the logs show
            # the rest app gets them correctly
            - name: MYSQL_ROOT_USERNAME
              valueFrom:
                secretKeyRef:
                  name: db-credentials
                  key: db-username
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: db-credentials
                  key: db-password
            # I hard-coded this to the externalName I created. 
            # Is that right?
            - name: MYSQL_URL
              value: db-service

问题:

我是否正确在应用层 namespace 中创建了externalName？

我需要以不同的方式定义它吗？

docker容器中的C#应用​​程序能否不引用db-service(这是externalName服务的名称)？

Answer 1

ExternalName类型服务应如下所示。注意使用svc而不是service。

apiVersion: v1
kind: Service
metadata:
  name: db-service
  namespace: app-layer
spec:
  type: ExternalName
  externalName: db-service.data-layer.svc.cluster.local
  ports:
    - port: 3306