如何仅连接到Mongo实例的主节点？

huangapple
go评论114阅读模式
英文:

How does one attach to just the primary node of a mongo instance?

问题

这可能是我对Mongo的工作方式或新的Go开发有误解，但我无法从Go中连接到我的Mongo实例。当我使用Studio 3T连接到我的Mongo实例时，可以正常连接，浏览表等。但是，如果我尝试使用Go模块连接，它会抱怨无法找到所有节点。它需要能够访问所有节点吗？我以为副本集本身应该处理复制？

例如，我有以下Go代码：

  1.     package main
  2.     
  3.     import (
  4.     	"context"
  5.     	"go.mongodb.org/mongo-driver/mongo"
  6.     	"go.mongodb.org/mongo-driver/mongo/options"
  7.     	"go.mongodb.org/mongo-driver/mongo/readpref"
  8.     	"log"
  9.     	"time"
  10.     )
  11.     
  12.     func main() {
  13.     	log.Println("Hello World!")
  14.     
  15.     	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
  16.     	defer cancel()
  17.     
  18.     	client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://MongoInsance:27017"))
  19.     	if err != nil {
  20.     		log.Fatal("Failed to connect to Mongo DB", err)
  21.     	}
  22.     
  23.     	if err := client.Ping(ctx, readpref.Primary()); err != nil {
  24.     		log.Fatal("Not actually connected ", err)
  25.     	}
  26.     
  27.     	res, err := client.ListDatabases(ctx, nil)
  28.     	if err != nil{
  29.     		log.Fatal("Failed to list databases")
  30.     	}
  31.     
  32.     	for _, val := range res.Databases {
  33.     		log.Println(val.Name)
  34.     	}
  35.     	defer disconnect(client, &ctx)
  36.     }
  37.     
  38.     func disconnect(client *mongo.Client, ctx *context.Context) {
  39.     	if err := client.Disconnect(*ctx); err != nil {
  40.     		panic(err)
  41.     	}
  42.     }

但是，当我运行上述代码时，收到以下错误响应：

  1. Not actually connected server selection error: context deadline exceeded, current topology: { Type: ReplicaSetNoPrimary, Servers: [{ Addr: mqtt-ingester-db-mast:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-mast: no such host }, { Addr: mqtt-ingester-db-rep1:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-rep1: no such host }, { Addr: mqtt-ingester-db-rep2:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-rep2: no such host }, ] }

我是否真的需要暴露所有副本集？
目前，我在主机MongoInstance上使用Docker运行主节点和2个从节点，主节点连接到端口27017：

  1. docker-compose.yml
  3.     services:
  4.       ...
  5.       mqtt-ingester-db-mast:
  6.         container_name: mqtt-ingester-db-mast
  7.         restart: always
  8.         image: mongo:latest
  9.         ports:
  10.           - 27017:27017
  11.         volumes:
  12.           - 'mongo_main:/data/db'
  13.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  14.       mqtt-ingester-db-rep1:
  15.         container_name: mqtt-ingester-db-rep1
  16.         restart: always
  17.         image: mongo:latest
  18.         expose:
  19.           - 27017
  20.         volumes:
  21.           - 'mongo_rep1:/data/db'
  22.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  23.       mqtt-ingester-db-rep2:
  24.         container_name: mqtt-ingester-db-rep2
  25.         restart: always
  26.         image: mongo:latest
  27.         expose:
  28.           - 27017
  29.         volumes:
  30.           - 'mongo_rep2:/data/db'
  31.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  32.       mqtt-ingester-setup:
  33.         image: mongo:latest
  34.         container_name: mqtt-ingester-setup
  35.         links:
  36.           - mqtt-ingester-db-mast:mqtt-ingester-db-mast
  37.           - mqtt-ingester-db-rep1:mqtt-ingester-db-rep1
  38.           - mqtt-ingester-db-rep2:mqtt-ingester-db-rep2
  39.         depends_on:
  40.           - mqtt-ingester-db-mast
  41.           - mqtt-ingester-db-rep1
  42.           - mqtt-ingester-db-rep2
  43.         volumes:
  44.           - ./mqtt-ingester:/scripts
  45.         restart: "no"
  46.         entrypoint: [ "bash", "/scripts/mqtt_ingester_setup.sh" ]
  47.       mqtt-ingester-explorer:
  48.         container_name: mqtt-ingester-explorer
  49.         restart: always
  50.         image: mongo-express:latest
  51.         ports:
  52.           - '8081:8081'
  53.         depends_on:
  54.           - mqtt-ingester-db-mast
  55.         links:
  56.           - mqtt-ingester-db-mast:mongo
  57.       ...
英文:

This might be me misunderstanding how Mongo works/new Go dev - but I'm not able to connect to my mongo instance from Go. When I connect to my Mongo instance using Studio 3T, I can connect just fine, browse the tables, etc. But If I try to connect using the Go module, it complains about not being able to find all the nodes. Is it necessary for it to be able to access all nodes? I thought the replica set itself was supposed to handle the replication?

For example, I have this Go code:

  1.     package main
  2.     
  3.     import (
  4.     	"context"
  5.     	"go.mongodb.org/mongo-driver/mongo"
  6.     	"go.mongodb.org/mongo-driver/mongo/options"
  7.     	"go.mongodb.org/mongo-driver/mongo/readpref"
  8.     	"log"
  9.     	"time"
  10.     )
  11.     
  12.     func main() {
  13.     	log.Println("Hello World!")
  14.     
  15.     	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
  16.     	defer cancel()
  17.     
  18.     	client, err := mongo.Connect(ctx, options.Client().ApplyURI("mongodb://MongoInsance:27017"))
  19.     	if err != nil {
  20.     		log.Fatal("Failed to connect to Mongo DB", err)
  21.     	}
  22.     
  23.     	if err := client.Ping(ctx, readpref.Primary()); err != nil {
  24.     		log.Fatal("Not actually connected ", err)
  25.     	}
  26.     
  27.     	res, err := client.ListDatabases(ctx, nil)
  28.     	if err != nil{
  29.     		log.Fatal("Failed to list databases")
  30.     	}
  31.     
  32.     	for _, val := range res.Databases {
  33.     		log.Println(val.Name)
  34.     	}
  35.     	defer disconnect(client, &ctx)
  36.     }
  37.     
  38.     func disconnect(client *mongo.Client, ctx *context.Context) {
  39.     	if err := client.Disconnect(*ctx); err != nil {
  40.     		panic(err)
  41.     	}
  42.     }

But the response I get when running said code gives the error:

  1. Not actually connected server selection error: context deadline exceeded, current topology: { Type: ReplicaSetNoPrimary, Servers: [{ Addr: mqtt-ingester-db-mast:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-mast: no such host }, { Addr: mqtt-ingester-db-rep1:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-rep1: no such host }, { Addr: mqtt-ingester-db-rep2:27017, Type: Unknown, Last error: connection() error occured during connection handshake: dial tcp: lookup mqtt-ingester-db-rep2: no such host }, ] }

Do I actually need to expose all the replica sets as well?
Currently I have the primary node and 2 secondary nodes running in docker on host MongoInstance, with the primary node attached to port 27017:

  1. docker-compose.yml
  3.     services:
  4.       ...
  5.       mqtt-ingester-db-mast:
  6.         container_name: mqtt-ingester-db-mast
  7.         restart: always
  8.         image: mongo:latest
  9.         ports:
  10.           - 27017:27017
  11.         volumes:
  12.           - 'mongo_main:/data/db'
  13.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  14.       mqtt-ingester-db-rep1:
  15.         container_name: mqtt-ingester-db-rep1
  16.         restart: always
  17.         image: mongo:latest
  18.         expose:
  19.           - 27017
  20.         volumes:
  21.           - 'mongo_rep1:/data/db'
  22.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  23.       mqtt-ingester-db-rep2:
  24.         container_name: mqtt-ingester-db-rep2
  25.         restart: always
  26.         image: mongo:latest
  27.         expose:
  28.           - 27017
  29.         volumes:
  30.           - 'mongo_rep2:/data/db'
  31.         entrypoint: [ "/usr/bin/mongod", "--bind_ip_all", "--replSet", "rs0" ]
  32.       mqtt-ingester-setup:
  33.         image: mongo:latest
  34.         container_name: mqtt-ingester-setup
  35.         links:
  36.           - mqtt-ingester-db-mast:mqtt-ingester-db-mast
  37.           - mqtt-ingester-db-rep1:mqtt-ingester-db-rep1
  38.           - mqtt-ingester-db-rep2:mqtt-ingester-db-rep2
  39.         depends_on:
  40.           - mqtt-ingester-db-mast
  41.           - mqtt-ingester-db-rep1
  42.           - mqtt-ingester-db-rep2
  43.         volumes:
  44.           - ./mqtt-ingester:/scripts
  45.         restart: "no"
  46.         entrypoint: [ "bash", "/scripts/mqtt_ingester_setup.sh" ]
  47.       mqtt-ingester-explorer:
  48.         container_name: mqtt-ingester-explorer
  49.         restart: always
  50.         image: mongo-express:latest
  51.         ports:
  52.           - '8081:8081'
  53.         depends_on:
  54.           - mqtt-ingester-db-mast
  55.         links:
  56.           - mqtt-ingester-db-mast:mongo
  57.       ...

答案1

得分: 1

是的。客户端需要看到复制集中的所有节点，这样当主节点宕机时，它们可以进行故障转移。

英文:

> Do I actually need to expose all the replica sets as well?

Yes. Clients need to see all nodes in a replica set, so they can fail over when master goes down.

huangapple
  • 本文由 发表于 2021年6月8日 19:52:27
  • 转载请务必保留本文链接：https://go.coder-hub.com/67886337.html
  • docker-compose
  • go
  • mongodb
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