Docker单节点MongoDB副本集连接被拒问题排查求助

问题现象 #

在Docker上搭建单节点MongoDB副本集后，Node.js应用通过Mongoose连接时被拒绝；但MongoDB作为独立实例运行时连接正常。

连接代码 #

mongoose.connect("mongodb://admin:secretpass@app_mongodb:27017/dbname?authSource=admin&replicaSet=rs0")

错误信息 #

/var/www/worker/node_modules/mongoose/lib/connection.js:824
const serverSelectionError = new ServerSelectionError();
                               ^
MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017

MongoDB日志 #

{"t":{"$date":"2023-01-27T10:22:46.410+00:00"},"s":"I",  "c":"NETWORK",  "id":22943,   "ctx":"listener","msg":"Connection accepted","attr":{"remote":"172.18.0.10:41318","uuid":"2e1ccbc5-3162-4f64-80f3-8be580079ef6","connectionId":68,"connectionCount":11}}
{"t":{"$date":"2023-01-27T10:22:46.417+00:00"},"s":"I",  "c":"NETWORK",  "id":51800,   "ctx":"conn68","msg":"client metadata","attr":{"remote":"172.18.0.10:41318","client":"conn68","doc":{"driver":{"name":"nodejs|Mongoose","version":"4.11.0"},"os":{"type":"Linux","name":"linux","architecture":"x64","version":"5.10.0-12-amd64"},"platform":"Node.js v19.5.0, LE (unified)","version":"4.11.0|6.7.5"}}}
{"t":{"$date":"2023-01-27T10:22:46.425+00:00"},"s":"I",  "c":"NETWORK",  "id":22944,   "ctx":"conn68","msg":"Connection ended","attr":{"remote":"172.18.0.10:41318","uuid":"2e1ccbc5-3162-4f64-80f3-8be580079ef6","connectionId":68,"connectionCount":10}}

docker-compose.yml配置 #

version: '3.8'

services:
    mongodb:
        container_name: app_mongodb
        build:
            dockerfile: ./Dockerfile
            x-bake:
                no-cache: true
        environment:
            - MONGO_INITDB_ROOT_USERNAME=admin
            - MONGO_INITDB_ROOT_PASSWORD=secretpass
        volumes:
            - ./db:/data/db
        networks:
            - proxy
        restart: unless-stopped
    worker:
        container_name: app_worker
        image: "node:latest"
        command: "npm run dev"
        user: "node"
        working_dir: /var/www/worker
        environment:
            WAIT_HOSTS: app_mongodb:27017
        volumes:
            - ./worker:/var/www/worker
        networks:
            - proxy
        links:
            - mongodb
        depends_on:
            - mongodb
        restart: unless-stopped
networks:
    proxy:
        external: true

Dockerfile内容 #

FROM mongo

# 创建副本集密钥文件
RUN echo "secretpasswordkey" > "/tmp/replica.key"
RUN chmod 600 /tmp/replica.key
RUN chown 999:999 /tmp/replica.key

CMD ["mongod", "--replSet", "rs0", "--bind_ip_all", "--keyFile", "/tmp/replica.key"]

手动执行的副本集初始化命令 #

rs.initiate({_id: 'rs0', members: [{_id:1, 'host':'127.0.0.1:27017'}]})

副本集状态（已成功初始化） #

rs0 [direct: primary] admin> rs.status()
{
  set: 'rs0',
  date: ISODate("2023-01-27T10:35:44.062Z"),
  myState: 1,
  term: Long("1"),
  syncSourceHost: '',
  syncSourceId: -1,
  heartbeatIntervalMillis: Long("2000"),
  majorityVoteCount: 1,
  writeMajorityCount: 1,
  votingMembersCount: 1,
  writableVotingMembersCount: 1,
  optimes: {
    lastCommittedOpTime: { ts: Timestamp({ t: 1674815739, i: 1 }), t: Long("1") },
    lastCommittedWallTime: ISODate("2023-01-27T10:35:39.161Z"),
    readConcernMajorityOpTime: { ts: Timestamp({ t: 1674815739, i: 1 }), t: Long("1") },
    appliedOpTime: { ts: Timestamp({ t: 1674815739, i: 1 }), t: Long("1") },
    durableOpTime: { ts: Timestamp({ t: 1674815739, i: 1 }), t: Long("1") },
    lastAppliedWallTime: ISODate("2023-01-27T10:35:39.161Z"),
    lastDurableWallTime: ISODate("2023-01-27T10:35:39.161Z")
  },
  lastStableRecoveryTimestamp: Timestamp({ t: 1674815679, i: 1 }),
  electionCandidateMetrics: {
    lastElectionReason: 'electionTimeout',
    lastElectionDate: ISODate("2023-01-27T10:25:49.015Z"),
    electionTerm: Long("1"),
    lastCommittedOpTimeAtElection: { ts: Timestamp({ t: 1674815148, i: 1 }), t: Long("-1") },
    lastSeenOpTimeAtElection: { ts: Timestamp({ t: 1674815148, i: 1 }), t: Long("-1") },
    numVotesNeeded: 1,
    priorityAtElection: 1,
    electionTimeoutMillis: Long("10000"),
    newTermStartDate: ISODate("2023-01-27T10:25:49.082Z"),
    wMajorityWriteAvailabilityDate: ISODate("2023-01-27T10:25:49.111Z")
  },
  members: [
    {
      _id: 1,
      name: '127.0.0.1:27017',
      health: 1,
      state: 1,
      stateStr: 'PRIMARY',
      uptime: 643,
      optime: { ts: Timestamp({ t: 1674815739, i: 1 }), t: Long("1") },
      optimeDate: ISODate("2023-01-27T10:35:39.000Z"),
      lastAppliedWallTime: ISODate("2023-01-27T10:35:39.161Z"),
      lastDurableWallTime: ISODate("2023-01-27T10:35:39.161Z"),
      syncSourceHost: '',
      syncSourceId: -1,
      infoMessage: '',
      electionTime: Timestamp({ t: 1674815149, i: 1 }),
      electionDate: ISODate("2023-01-27T10:25:49.000Z"),
      configVersion: 1,
      configTerm: 1,
      self: true,
      lastHeartbeatMessage: ''
    }
  ],
  ok: 1,
  '$clusterTime': {
    clusterTime: Timestamp({ t: 1674815739, i: 1 }),
    signature: {
      hash: Binary(Buffer.from("a211cfe3faa237bf8a30ccbc8ca929eea704f467", "hex"), 0),
      keyId: Long("7193276291800367109")
    }
  },
  operationTime: Timestamp({ t: 1674815739, i: 1 })
}

问题原因 #

核心问题出在副本集成员的host配置：初始化副本集时用了127.0.0.1:27017作为节点地址，但在Docker环境中，这个地址仅代表MongoDB容器自身。当Node.js应用连接时，MongoDB会返回副本集的节点列表（即127.0.0.1:27017），导致应用尝试连接自己容器的127.0.0.1端口，自然被拒绝。

解决方案 #

1. 修改副本集初始化命令 #

将初始化命令中的host改为Docker容器名称app_mongodb（容器间可通过此域名相互访问）：

rs.initiate({_id: 'rs0', members: [{_id:1, 'host':'app_mongodb:27017'}]})

2. 自动执行副本集初始化（无需手动操作） #

MongoDB镜像会自动执行/docker-entrypoint-initdb.d/目录下的脚本，可将初始化逻辑集成到构建流程：

• 创建init-replica.js文件：

rs.initiate({
  _id: 'rs0',
  members: [
    { _id: 1, host: 'app_mongodb:27017' }
  ]
})

• 修改Dockerfile，添加COPY命令将脚本复制到容器内：

FROM mongo

# 创建副本集密钥文件
RUN echo "secretpasswordkey" > "/tmp/replica.key"
RUN chmod 600 /tmp/replica.key
RUN chown 999:999 /tmp/replica.key

# 复制副本集初始化脚本
COPY init-replica.js /docker-entrypoint-initdb.d/

CMD ["mongod", "--replSet", "rs0", "--bind_ip_all", "--keyFile", "/tmp/replica.key"]

3. 验证连接配置 #

你的Mongoose连接字符串已正确使用app_mongodb作为地址，修改副本集配置后即可正常连接。

内容的提问来源于stack exchange，提问作者Finsky