学习Kubernetes部署Mongo与Mongo Express遇数据库连接故障

问题说明 #

正在学习Kubernetes，部署Mongo和Mongo Express节点时遇到连接问题。执行minikube service mongo-express-service启动服务后页面无法正常工作，报错信息：Could not connect to database using connectionString: mongodb://-n 'username'

相关配置与信息 #

1. 核心配置文件 #

Mongo-express Deployment及Service

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_SERVER
              valueFrom:
                configMapKeyRef:
                  name: mongodb-configmap
                  key: database_url
            - name: ME_CONFIG_MONGODB_ADMINUSERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: ME_CONFIG_BASICAUTH_USERNAME
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: ME_CONFIG_MONGODB_ADMINPASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
            - name: ME_CONFIG_BASICAUTH_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mongodb-secret
                  key: mongo-root-username
---
apiVersion: v1
kind: Service
metadata:
  name: mongo-express-service
spec:
  selector:
    app: mongo-express
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 8081
      targetPort: 8081
      nodePort: 30000

ConfigMap

ConfigMap名称为mongodb-configmap，其中database_url键的值设置为mongodb-service（对应Mongo Service的名称）

Mongo Deployment及Service

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
        - name: mongodb
          image: mongo
          ports:
            - containerPort: 27017
              hostPort: 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
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

Secret

Secret名称为mongodb-secret，包含两个键：mongo-root-username（存储Mongo管理员用户名）、mongo-root-password（存储Mongo管理员密码）

问题排查与修复 #

核心问题 #

Mongo-express的环境变量配置存在明显错误：

• ME_CONFIG_MONGODB_ADMINPASSWORD（Mongo认证密码）错误引用了mongo-root-username键
• ME_CONFIG_BASICAUTH_PASSWORD（Mongo Express自身登录密码）同样错误引用了mongo-root-username键

这两个错误会导致连接Mongo时使用用户名作为密码，认证失败，同时生成格式异常的连接字符串，最终出现页面无法访问的问题。

修复后的Mongo-express环境变量配置 #

env:
  - name: ME_CONFIG_MONGODB_SERVER
    valueFrom:
      configMapKeyRef:
        name: mongodb-configmap
        key: database_url
  - name: ME_CONFIG_MONGODB_ADMINUSERNAME
    valueFrom:
      secretKeyRef:
        name: mongodb-secret
        key: mongo-root-username
  - name: ME_CONFIG_BASICAUTH_USERNAME
    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_BASICAUTH_PASSWORD
    valueFrom:
      secretKeyRef:
        name: mongodb-secret
        key: mongo-root-password

修复步骤 #

1. 编辑Mongo-express的Deployment配置文件，替换上述错误的环境变量配置
2. 应用更新后的配置：kubectl apply -f <你的mongo-express配置文件名>.yaml
3. 等待Pod重启完成后，再次执行minikube service mongo-express-service测试服务连接

内容的提问来源于stack exchange，提问作者mohmad khaled