无法连接到MongoDB:服务器选择错误:服务器选择超时

Question

我已经设置了Percona MongoDB出口商，当我试图为我的MongDB实例刮取度量标准时，我得到了一个错误：

An error has occurred while connecting to MongoDB:
cannot connect to MongoDB: server selection error: server selection timeout, current topology: { Type: Unknown, Servers: [{ Addr: mongodb-headless-service.labs.svc.cluster.local:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mongodb-headless-service.svc.cluster.local on 159.XX.XX.XX:XX: no such host }, ] }

MongoDB和Percona导出程序都部署在Kubernetes上的相同的名称空间中，我创建了一个用户(在管理级别)来提取度量：

db.createUser({ user: "promt", pwd: "abc123", roles: [ { role: "clusterMonitor", db: "admin" },{ role: "read", db: "local" } ], mechanisms:["SCRAM-SHA-1"]})

要验证出口商是否能够从我正在使用的MongoDB实例中获取任何度量标准，请执行以下操作：

kubectl -n labs port-forward service/mongodb-exporter 9216

我可以进入http://localhost:9216的出口商

在Percona MongoDB出口商部署中，我将MongoDB指定如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-exporter
  namespace: labs
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb-exporter
  template:
    metadata:
      labels:
        app: mongodb-exporter
    spec:
      containers:
      - name: mongodb-exporter
        image: percona/mongodb_exporter:0.30
        imagePullPolicy: "IfNotPresent"
        args:
        - "--mongodb.direct-connect=false"
        - "--mongodb.uri=mongodb://promt:abc123@mongo-headless-service.svc.cluster.local/admin"
        ports:
        - name: metrics
          containerPort: 9216
        resources:
          requests:
            memory: 128Mi
            cpu: 250m

我尝试了许多选项，但它们都导致了相同的错误

1. 将k8s命名空间添加到mongo-uri --mongodb.uri=mongodb://promt:abc123@mongodb-headless-service.labs.svc.cluster.local/admin
2. 为SSL --mongodb.uri=mongodb://promt:abc123@mongodb-headless-service.svc.cluster.local/admin?ssl=false添加选项
3. 从使用k8s无头服务切换到ClusterIP

--mongodb.uri=mongodb://promt:abc123@mongo-single-clusterip.labs.svc.cluster.local/admin

1. 启用直接连接选项

• - "--mongodb.uri=mongodb://promt:abc123@mongodb-headless-service.svc.cluster.local/admin“

对于所有这些选项，我还尝试了添加ssl选项和命名空间的变体，但这在所有情况下都失败了，因为相同的错误都是。

我的MongoDB实例是一个独立的部署，定义如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  namespace: labs
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
      - name: mongodb
        image: docker.io/bitnami/mongodb:4.4.6-debian-10-r0
        imagePullPolicy: "IfNotPresent"
        securityContext:
            runAsNonRoot: true
            runAsUser: 1001
        ports:
          - containerPort: 27017
        env:
            - name: MONGO_INITDB_ROOT_USERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret-amended
                  key: mongo-root-username
            - name: MONGO_INITDB_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret-amended
                  key: mongo-root-password
        volumeMounts: 
            - mountPath: /data/db
              name: mongodb-vol
      volumes:
      - name: mongodb-vol
        persistentVolumeClaim:
          claimName: mongodb-claim
---
apiVersion: v1
kind: Service
metadata:
  name: mongodb-service
  namespace: labs
spec:
  type: NodePort
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017 
---
apiVersion: v1
kind: Service
metadata:
  name: mongodb-headless-service
  namespace: labs
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017 
---
apiVersion: v1
kind: Service
metadata:
  name: mongo-single-clusterip
  namespace: labs
spec:
  type: ClusterIP
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

对于上下文，我将遵循给定的这里和这里示例。

我遗漏了什么？

Answer 1

在返回的错误消息中说明了原因：

error occured during connection handshake: dial tcp: lookup mongodb-headless-service.svc.cluster.local on 159.XX.XX.XX:XX: no such host

此FQDN的DNS查找：mongodb-headless-service.svc.cluster.local失败。

您可以通过这里的步骤来确认您的DNS是否已正确设置：https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/

Answer 2

您需要在配置中将mongoDB URI更改为mongodb-headless-service.labs.svc.cluster.local &它应该可以很好地工作。