k8s pod未能连接mongodb

Question

我试着在youtube https://www.youtube.com/watch?v=X48VuDVv0do&t=5428s上做一个https://www.youtube.com/watch?v=X48VuDVv0do&t=5428s教程。当我创建部署mongo时，发生了一个错误，即k8s pod未能连接mongodb。请帮帮忙！

kubectl logs命令检索的pod错误信息：

Welcome to mongo-express
------------------------


(node:7) [MONGODB DRIVER] Warning: Current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
Could not connect to database using connectionString: mongodb://username:password@mongodb-service:27017/"
(node:7) UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [mongodb-service:27017] on first connect [Error: getaddrinfo ENOTFOUND mongodb-service
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:66:26) {
  name: 'MongoNetworkError'
}]
    at Pool.<anonymous> (/node_modules/mongodb/lib/core/topologies/server.js:441:11)
    at Pool.emit (events.js:314:20)
    at /node_modules/mongodb/lib/core/connection/pool.js:564:14
    at /node_modules/mongodb/lib/core/connection/pool.js:1000:11
    at /node_modules/mongodb/lib/core/connection/connect.js:32:7
    at callback (/node_modules/mongodb/lib/core/connection/connect.js:300:5)
    at Socket.<anonymous> (/node_modules/mongodb/lib/core/connection/connect.js:330:7)
    at Object.onceWrapper (events.js:421:26)
    at Socket.emit (events.js:314:20)
    at emitErrorNT (internal/streams/destroy.js:92:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:60:3)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
(node:7) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:7) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

配置文件、kubernetes组件的配置文件供您参考。

 1. kubernetes secret 
apiVersion: v1
kind: Secret
metadata:
        name: mongodb-secret
type: Opaque
data:
        mongo-root-username: dXNlcm5hbWU=
        mongo-root-password: cGFzc3dvcmQ=```


2. mongodb deployment & service
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
        - name: mongodb
          image: mongo
          ports:
            - containerPort: 27017
          env:
            - name: MONGO_INITDB_ROOT_USERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: MONGO_INITDB_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-password
---
apiVersion: v1
kind: Service
metadata:
  name: mongo-service
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017```

 3. kubernetes configmap
```apiVersion: v1

种类: ConfigMap

元数据：

名称: mongodb-configmap

数据：

database_url: mongodb-service``

1. mongo-express

kind: Deployment
metadata:
  name: mongo-express
  labels:
    app: mongo-express
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo-express
  template:
    metadata:
      labels:
        app: mongo-express
    spec:
      containers:
        - name: mongo-express
          image: mongo-express
          ports:
            - containerPort: 8081
          env:
            - name: ME_CONFIG_MONGODB_ADMINUSERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: ME_CONFIG_MONGODB_ADMINPASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-password
            - name: ME_CONFIG_MONGODB_SERVER
              valueFrom:
                configMapKeyRef:
                  name: mongodb-configmap
                  key: database_url

Answer 1

我遵循同样的教程，也面临着同样的问题。问题就在码头上。与码头启动小码头的问题，似乎码头有一定的局限性。如果您使用的是MacOS，安装hyperkit；如果使用Windows安装Hyper-V；如果使用的是linux发行版，则安装virtualbox。

然后用您安装的虚拟机启动minikube，如下所示

minikube start --driver=virtualbox

Answer 2

ConfigMap引用不存在的服务。如果在2.MongoDBDeploy&Service中，在服务部分将元数据名更改为name: mongodb-service，那么一切都应该正常工作。见以下文件：

mongo-secret.yml

apiVersion: v1
kind: Secret
metadata:
  name: mongodb-secret
type: Opaque
data:
  mongo-root-username: dXNlcm5hbWU=
  mongo-root-password: cGFzc3dvcmQ=

mongo-configmap.yml

apiVersion: v1
kind: ConfigMap
metadata:
  name: mongodb-configmap
data:
  database_url: mongodb-service

mongodb.yml <=此文件更改

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
        - name: mongodb
          image: mongo
          ports:
            - containerPort: 27017
          env:
            - name: MONGO_INITDB_ROOT_USERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: MONGO_INITDB_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-password
---
apiVersion: v1
kind: Service
metadata:
  name: mongodb-service # <= THIS HAS CHANGED
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

mongo-express.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongo-express
  labels:
    app: mongo-express
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo-express
  template:
    metadata:
      labels:
        app: mongo-express
    spec:
      containers:
        - name: mongo-express
          image: mongo-express
          ports:
            - containerPort: 8081
          env:
            - name: ME_CONFIG_MONGODB_ADMINUSERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: ME_CONFIG_MONGODB_ADMINPASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-password
            - name: ME_CONFIG_MONGODB_SERVER
              valueFrom:
                configMapKeyRef:
                  name: mongodb-configmap
                  key: database_url

要进行测试，请确保首先运行秘密和configmap：

$ kubectl apply -f mongo-secret.yml
$ kubectl apply -f mongo-configmap.yml
$ kubectl apply -f mongodb.yml
$ kubectl apply -f mongo-express.yml

最后，如果要确保应用程序工作正常，可以将此服务添加到mongo-express.yml文件中：

---
apiVersion: v1
kind: Service
metadata:
  name: mongo-express-service
spec:
  selector:
    app: mongo-express
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 8081
      targetPort: 8081

现在，在您的终端中运行minikube tunnel，在浏览器中访问localhost:8081。

祝好运!