Cannot connect from node to mongo replicaset in docker

Question

I've set up a docker network in which I have set up 3 mongo containers.

Summary of what I've done:

1. created a docker network in which I set up 3 mongo docker containers

2. open up the mongo shell for first node and set up the config for the replica set

3. tried to connect from node app, failed

4. successfully connect from mongo shell to replicaSet

Below I give a more detailed view of what I've tried.

These are the following cmds I have run for docker:

docker network create my-mongo-cluster

docker run -d -p 30001:27017 --name mongo1 --net my-mongo-cluster mongo mongod --replSet my-mongo-set

docker run -d -p 30002:27017 --name mongo2 --net my-mongo-cluster mongo mongod --replSet my-mongo-set

docker run -d -p 30003:27017 --name mongo3 --net my-mongo-cluster mongo mongod --replSet my-mongo-set

docker exec -it mongo1 mongo

config = { "_id": "my-mongo-set", "members": [{"_id": 0, "host": "mongo1:27017"},{"_id": 1,"host": "mongo2:27017"},{"_id": 3,"host": "mongo3:27017" }   ]}

rs.initiate(config)

From MongoDB Compass I've connected to the primary node, 192.168.1.3:30001 and created a database test with one collection user.

From node I try the following:

const app = require('express')();
const mongoose = require('mongoose');

//set up mongo connect
const uri = 'mongodb://192.168.1.3:30001,192.168.1.3:30002,192.168.1.3:30003/test'
mongoose.connect(uri, {useNewUrlParser: true, replicaSet: 'my-mongo-set'})
  .then(() => console.log("MongoDB Connected"))
  .catch(error => console.log(error));

From which I get

Debugger attached.
{ MongoNetworkError: failed to connect to server [mongo3:27017] on first connect [MongoNetworkError: getaddrinfo ENOTFOUND mongo3 mongo3:27017]
    at Pool.<anonymous> (C:\Workspaces\intelij\trial&error\spring-reactive-security\mongo-transactional\node_modules\mongodb-core\lib\topologies\server.js:431:11)
    at Pool.emit (events.js:198:13)
    at connect (C:\Workspaces\intelij\trial&error\spring-reactive-security\mongo-transactional\node_modules\mongodb-core\lib\connection\pool.js:557:14)
    at makeConnection (C:\Workspaces\intelij\trial&error\spring-reactive-security\mongo-transactional\node_modules\mongodb-core\lib\connection\connect.js:39:11)
    at callback (C:\Workspaces\intelij\trial&error\spring-reactive-security\mongo-transactional\node_modules\mongodb-core\lib\connection\connect.js:261:5)
    at Socket.err (C:\Workspaces\intelij\trial&error\spring-reactive-security\mongo-transactional\node_modules\mongodb-core\lib\connection\connect.js:286:7)
    at Object.onceWrapper (events.js:286:20)
    at Socket.emit (events.js:198:13)
    at emitErrorNT (internal/streams/destroy.js:91:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:59:3)
    at process._tickCallback (internal/process/next_tick.js:63:19)
  name: 'MongoNetworkError',
  errorLabels: [ 'TransientTransactionError' ],
  [Symbol(mongoErrorContextSymbol)]: {} }
Waiting for the debugger to disconnect...

Process finished with exit code 0

but if I try from mongo shell, I am able to connect:

mongo "mongodb://192.168.1.3:30001,192.168.1.3:30002,192.168.1.3:30003/test"
MongoDB shell version v4.0.10
connecting to: mongodb://192.168.1.3:30001,192.168.1.3:30002,192.168.1.3:30003/test?gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("89994673-11c2-4d6c-8cb5-04041094c147") }
MongoDB server version: 4.0.10
Server has startup warnings:
2019-07-20T06:22:00.476+0000 I STORAGE  [initandlisten]
2019-07-20T06:22:00.476+0000 I STORAGE  [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2019-07-20T06:22:00.476+0000 I STORAGE  [initandlisten] **          See http://dochub.mongodb.org/core/prodnotes-filesystem
2019-07-20T06:22:01.185+0000 I CONTROL  [initandlisten]
2019-07-20T06:22:01.185+0000 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2019-07-20T06:22:01.185+0000 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2019-07-20T06:22:01.185+0000 I CONTROL  [initandlisten]
---
Enable MongoDB's free cloud-based monitoring service, which will then receive and display
metrics about your deployment (disk utilization, CPU, operation statistics, etc).

The monitoring data will be available on a MongoDB website with a unique URL accessible to you
and anyone you share the URL with. MongoDB may use this information to make product
improvements and to suggest MongoDB products and deployment options to you.

To enable free monitoring, run the following command: db.enableFreeMonitoring()
To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---

my-mongo-set:PRIMARY>

Answer 1

Ok, so I've finally figure out what I was doing wrong. Maybe this will help someone:

you either go in C:\Windows\System32\drivers\etc and put in hosts MACHINE_IP mongo1 mongo2 mongo3, or just replace the config as:

config = { "_id": "my-mongo-set", "members": [{"_id": 0, "host": "MACHINE_IP:30001"},{"_id": 1,"host": "<MACHINE_IP>:30002"},{"_id": 2,"host": "<MACHINE_IP>:30003" }   ]}

also I had some problems with mongo figuring out which one is primary so I slightly modified the docker runs, by adding MONGODB_REPLICA_SET_MODE and MONGODB_PRIMARY_HOST as:

docker run -d -p 30001:27017 --name mongo1 -e MONGODB_REPLICA_SET_MODE=primary --net my-mongo-cluster mongo mongod --replSet my-mongo-set

docker run -d -p 30002:27017 --name mongo2 -e MONGODB_REPLICA_SET_MODE=secondary -e MONGODB_PRIMARY_HOST=mongo1 --net my-mongo-cluster mongo mongod --replSet my-mongo-set

docker run -d -p 30003:27017 --name mongo3 -e MONGODB_REPLICA_SET_MODE=secondary -e MONGODB_PRIMARY_HOST=mongo1 --net my-mongo-cluster mongo mongod --replSet my-mongo-set