在 Kubernetes 中无法连接到 Redis：Redis connection to localhost:6379 failed

如何解决在 Kubernetes 中无法连接到 Redis：Redis connection to localhost:6379 failed

我已经部署了一个连接到 Redis pod 和 Mongodb pod 的后端 API。 API 已成功建立到 mongodb 的连接，但没有建立到 Redis 的连接，出现以下错误，有人知道如何修复吗？

Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1088:14) 
2021-01-18 09:22:36 error: uncaughtException: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1088:14) {"error":{"errno":"ECONNREFUSED","code":"ECONNREFUSED","syscall":"connect","address":"127.0.0.1","port":6379},"stack":"Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379\n    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1088:14)","exception":true,"date":"Mon Jan 18 2021 09:22:36 GMT+0000 (Coordinated Universal Time)","process":{"pid":1,"uid":0,"gid":0,"cwd":"/usr/src/app","execPath":"/usr/local/bin/node","version":"v11.14.0","argv":["/usr/local/bin/node","/usr/src/app/dist/server.js"],"memoryUsage":{"rss":101421056,"heapTotal":73146368,"heapUsed":37365856,"external":19092480}},"os":{"loadavg":[1.232421875,0.8720703125,0.69482421875],"uptime":281868},"trace":[{"column":14,"file":"net.js","function":"TCPConnectWrap.afterConnect [as oncomplete]","line":1088,"method":"afterConnect [as oncomplete]","native":false}]}

后端.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: backend-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: backend-api
  template:
    metadata:
      labels:
        app: backend-api
    spec:
      containers:
      - image: <image_name>
        name: backend-test
        imagePullPolicy: Never
        ports:
        - containerPort: 8080
        env: 
        - name: MONGODB_URL
          value: mongodb://localhost:27017/dt?authSource=admin
        - name: REDIS_URL
          value: redis://localhost:6379      
      restartPolicy: Always
---
kind: Service
apiVersion: v1
metadata:
  name: backend-svc
  labels:
    app: backend-svc
spec:
  selector:
    app: backend-api
  ports:
    - name: http 
      port: 8080
      targetPort: 8080

redis.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-master
  labels:
    app: redis
spec:
  selector:
    matchLabels:
      app: redis
  replicas: 1
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: master
        image: k8s.gcr.io/redis:e2e  # or just image: redis
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
        - containerPort: 6379
---
apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    app: redis
spec:
  ports:
  - name: redis
    port: 6379
    targetPort: 6379
  selector:
    app: redis

我也尝试将端口转发到 pod 上的端口，但没有成功

kubectl port-forward redis-master-765d459796-258hz 6379:6379

解决方法

localhost 用于在一个 Pod 中的容器之间进行通信。试试 redis-master:6379

,

localhost 仅用于本地连接。这意味着您只能从带有 localhost 的 pod 内部进行连接。当您需要从外部访问时，您需要使用服务。然后服务将解析您的 IP 地址。当您尝试通过 service 访问时。这是需要在您的 yaml 中更新的代码。

        - name: REDIS_URL
          value: redis://redis-master.default.svc.cluster.local:6379  

ref

模板类似于 my_Service_Name.my_Namespace.svc.cluster-domain.example ，但您可以跳过 cluster-domain.example 部分。只有 Service_Name.Namespace.svc 可以正常工作。所以对你来说就是：redis-master.default.svc

这是更新的代码：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: backend-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: backend-api
  template:
    metadata:
      labels:
        app: backend-api
    spec:
      containers:
      - image: <image_name>
        name: backend-test
        imagePullPolicy: Never
        ports:
        - containerPort: 8080
        env: 
        - name: MONGODB_URL
          value: mongodb://localhost:27017/dt?authSource=admin
        - name: REDIS_URL
          value: redis://redis-master.default.svc.cluster.local:6379      
      restartPolicy: Always
---
kind: Service
apiVersion: v1
metadata:
  name: backend-svc
  labels:
    app: backend-svc
spec:
  selector:
    app: backend-api
  ports:
    - name: http 
      port: 8080
      targetPort: 8080