无法使用 mongoose 连接到 mongodb 数据库

Question

Hey so i have a school assignment that requires me to connect to a mongodb database with mongoose and koa. I have my database set up on Docker and i can access it through mongodb Compass so that should be all right. But when i try to use mongoose, i get an error message on the docker display.

My code:

server.js

const Koa = require('koa');
const mongoose = require('mongoose');

const router = require('./routes');


const app = new Koa();
app.use(require('koa-body')());
app.use(router.routes());

mongoose.connect(process.env.MONGODB_URI, { useNewUrlParser: true, useUnifiedTopology: true })
    .then(() => {
        const listener = app.listen(process.env.APP_PORT || 3000, () =>
            console.log('App started on port ' + listener.address().port)
        )
    })
    .catch((error) => {
        console.log(error)
        process.exit(1)
    })

//    app.proxy = true;
module.exports = app;

docker-compose.yml

mongodb:
    image: 'mongo:4.4.0'
    command: '--auth'
    container_name: mongodb_container
    volumes:
      - './data/mongo:/data/db:delegated'
    ports:
      - '27017:27017'
    environment: 
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: example
      MONGO_INITDB_DATABASE: database1

  node-service-two:
    depends_on:
      - mongodb
    build:
      context: '../Test-II-node'
    ports:
      - '3000:3000'
    volumes:
      - '../Test-I-node:/home/node/app:delegated'
    environment:
      MONGODB_URI: mongodb://root:example@localhost:27017/two?authSource=admin
    command: 'run dev'

scripts from package.json

  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node src/server.js",
    "dev": "nodemon src/server.js"
  }

the error message

[nodemon] starting `node src/server.js`

MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017

at NativeConnection.Connection.openUri (/home/node/app/node_modules/mongoose/lib/connection.js:800:32)

at /home/node/app/node_modules/mongoose/lib/index.js:341:10

at /home/node/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:31:5

at new Promise (<anonymous>)

at promiseOrCallback (/home/node/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:30:10)

at Mongoose.connect (/home/node/app/node_modules/mongoose/lib/index.js:340:10)

at Object.<anonymous> (/home/node/app/src/server.js:11:10)

at Module._compile (internal/modules/cjs/loader.js:1075:30)

at Object.Module._extensions..js (internal/modules/cjs/loader.js:1096:10)

at Module.load (internal/modules/cjs/loader.js:940:32)

at Function.Module._load (internal/modules/cjs/loader.js:781:14)

at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)

at internal/main/run_main_module.js:17:47 {

reason: TopologyDescription {

type: 'Single',

setName: null,

maxSetVersion: null,

maxElectionId: null,

servers: Map(1) { 'localhost:27017' => [ServerDescription] },

stale: false,

compatible: true,

compatibilityError: null,

logicalSessionTimeoutMinutes: null,

heartbeatFrequencyMS: 10000,

localThresholdMS: 15,

commonWireVersion: null

}
}

[nodemon] app crashed - waiting for file changes before starting...

Im pretty sure its got something to do with the javascript promise or it cant find the mongodb url but i havent been able to pinpoint the issue. I also have all the necessary packages installed. Its my first time using node so any help would be great.

Answer 1

When using docker-compose you have to remember that each service is its own container. when your Node.js service is looking for localhost it is looking at itself.

To fix this point mongoose at the MongoDB container by using its service name specified in your docker-compose: MONGODB_URI: mongodb://root:example@mongodb:27017/two?authSource=admin