docker配置mongodb replica set

1. 通过docker-compose来构建

version: '3'
services:
  # 这是一个mongod实例的配置
  mongo-master:
    container_name: mongo-master
    image: mongo:4.4.3
    environment:
      MONGO_INITDB_ROOT_USERNAME: username
      MONGO_INITDB_ROOT_PASSWORD: password
      MONGO_INITDB_DATABASE: admin
    volumes:
    - ./data/db-master:/data/db
    - ./data/key_file:/data/configdb/key_file
    ports:
    - 27017:27017
    command: ["mongod", "--bind_ip_all", "--dbpath", "/data/db", "--journal", "--logappend", "--storageEngine", "wiredTiger", "--replSet", "rs", "--oplogSize", "128", "--auth", "--keyFile=/data/configdb/key_file"]
  # 然后复制，一共三份配置，分别是主(master)/从(slave)/仲裁(arbiter)
  mongo-slave:
    container_name: mongo-slave
    image: mongo:4.4.3
    environment:
      MONGO_INITDB_ROOT_USERNAME: username
      MONGO_INITDB_ROOT_PASSWORD: password
      MONGO_INITDB_DATABASE: admin
    volumes:
    - ./data/db-slave:/data/db
    - ./data/key_file:/data/configdb/key_file
    ports:
    - 27017:27017
    command: ["mongod", "--bind_ip_all", "--dbpath", "/data/db", "--journal", "--logappend", "--storageEngine", "wiredTiger", "--replSet", "rs", "--oplogSize", "128", "--auth", "--keyFile=/data/configdb/key_file"]
  # arbiter
  mongo-arbiter:
    container_name: mongo-arbiter
    image: mongo:4.4.3
    environment:
      MONGO_INITDB_ROOT_USERNAME: username
      MONGO_INITDB_ROOT_PASSWORD: password
      MONGO_INITDB_DATABASE: admin
    volumes:
    - ./data/db-arbiter:/data/db
    - ./data/key_file:/data/configdb/key_file
    ports:
    - 27017:27017
    command: ["mongod", "--bind_ip_all", "--dbpath", "/data/db", "--journal", "--logappend", "--storageEngine", "wiredTiger", "--replSet", "rs", "--oplogSize", "128", "--auth", "--keyFile=/data/configdb/key_file"]

注意：如果使用的是mac系统，因为mac系统是虚拟机的方式，是无法直接mount mongo的/data目录的，因此需要建立named volume方式

version: '3'
services:
  mongo-master:
    # ... 省略
    volumes:
    - mongodata-master:/data/db
    - ./data/key_file:/data/configdb/key_file
# for MacOSX
volumes:
  mongodata-master:
    driver: local
    driver_opts:
      o: bind
      type: none
      device: $PWD/data/db-master

2. 创建key_file

openssl rand -base64 756 > key_file
chmod 400 key_file

3. 运行服务及配置replica set

docker-compose up
# 可以看到服务正常运行起来
# 然后通过命令进入到mongo控制台
docker exec -it mongo-master mongo
# 切换到admin
use admin
# 进行授权登录
db.auth({user: 'username', pwd: 'password'})
# 返回 1 代表授权成功，失败的情况会有错误信息
# 授权完成后，配置replica set
# 编写配置信息，因为这是在docker内部，hostname就是服务的名字，因此这里直接写 mongo-master这些就行。
config = {_id:"rs", version:1, members:[{_id:0, host:"mongo-master:27017", priority:5}, {_id:1, host:"mongo-slave:27017", priority:2}, {_id:2, host:"mongo-arbiter:27017", priority:3}]}
# 然后执行 rs.initiate 进行初始化
rs.initiate(config)
# 注意，如果初始化这里返回失败说auth fail什么，就是mongo服务器没有配置好auth参与与keyfile。群集的服务器之间通信，必须要配置好。

到此为止，配置完成。

4. 使用golang，mongo-drive创建连接

func GetMongoClient(dbName string) *mongo.Client {
  var uri string
  if isDebug {
    // debug下，是通过localhost访问replica set，通过参数connect=direct
    uri := fmt.Sprintf("mongodb://%s:%s@localhost:27017/%s?connect=direct",
                       MONGO_USERNAME,
                       MONGO_PASSWORD,
                       dbName)
  } else {
    // 正式环境，MONGO_X_HOST 是服务器HOST或k8s/docker中的hostname。
    uri := fmt.Sprintf("mongodb://%s:%s@%s:%s,%s:%s,%s:%s/%s",
                     MONGO_USERNAME,
                     MONGO_PASSWORD,
                     MONGO_1_HOST,
                     MONGO_1_PORT,
                     MONGO_2_HOST,
                     MONGO_2_PORT,
                     MONGO_3_HOST,
                     MONGO_3_PORT,
                     dbName)
  }
  // 参数
  clientOptions := options.Client().ApplyURI(uri)
  clientOptions.SetMaxPoolSize(5)
  clientOptions.SetAuth(options.Credential{
    Username: MONGO_USERNAME,
    Password: MONGO_PASSWORD,
  })
  clientOptions.SetReplicaSet("rs")
  // 发起连接
  ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
  defer cancel()
  client, err := mongo.Connect(ctx, clientOptions)
  return client
}