Connecting database (MongoDB) and backend (nodejs) running in docker containers [duplicate] - node.js

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MongoDB on with Docker "failed to connect to server [localhost:27017] on first connect "
(4 answers)
Closed 2 years ago.
First, I looked through several discussion with similar problems and it still did not work.
I have a mongodb docker container running, I did port forwarding with -p command
to be exact this is the command I ran:
sudo docker run -t -d -p 27017:27017 --name mongo mongo-0000
docker ps shows container running
9d9040a7bd66 mongo-0000 "docker-entrypoint.s…" 4 minutes ago Up 4 minutes 0.0.0.0:27017->27017/tcp mongo
as in another thread it was suggested to change mongodb bindip from 127.0.0.1 to 0.0.0.0 , which I also did (I tried both ways).
then I am trying to start up a backend app container with nodejs express backend app, I have had them working fine together on a VM, not on docker jet.
And i get following error
sudo docker run conduit-backend
Listening on port 3000
/ConduitReactApp/src/node_modules/mongodb/lib/server.js:261
process.nextTick(function() { throw err; })
^
Error [MongoError]: failed to connect to server [localhost:27017] on first connect
at Pool.<anonymous> (/ConduitReactApp/src/node_modules/mongodb-core/lib/topologies/server.js:313:35)
at Pool.emit (node:events:378:20)
at Connection.<anonymous> (/ConduitReactApp/src/node_modules/mongodb-core/lib/connection/pool.js:260:12)
at Object.onceWrapper (node:events:485:26)
at Connection.emit (node:events:378:20)
at Socket.<anonymous> (/ConduitReactApp/src/node_modules/mongodb-core/lib/connection/connection.js:162:49)
at Object.onceWrapper (node:events:485:26)
at Socket.emit (node:events:378:20)
at emitErrorNT (node:internal/streams/destroy:188:8)
at emitErrorCloseNT (node:internal/streams/destroy:153:3)
at processTicksAndRejections (node:internal/process/task_queues:81:21)
Emitted 'error' event on NativeConnection instance at:
at /ConduitReactApp/src/node_modules/mongoose/lib/connection.js:288:17
at NativeConnection.Connection.error (/ConduitReactApp/src/node_modules/mongoose/lib/connection.js:489:12)
at /ConduitReactApp/src/node_modules/mongoose/lib/connection.js:520:15
at /ConduitReactApp/src/node_modules/mongoose/lib/drivers/node-mongodb-native/connection.js:69:21
at /ConduitReactApp/src/node_modules/mongodb/lib/db.js:229:14
at Server.<anonymous> (/ConduitReactApp/src/node_modules/mongodb/lib/server.js:259:9)
at Object.onceWrapper (node:events:485:26)
at Server.emit (node:events:378:20)
at Pool.<anonymous> (/ConduitReactApp/src/node_modules/mongodb-core/lib/topologies/server.js:313:21)
at Pool.emit (node:events:378:20)
[... lines matching original stack trace ...]
at Socket.emit (node:events:378:20)
Also, inside app.js (in the backend app) for connecting to mongoDB it reads so
if(isProduction){
mongoose.connect(process.env.MONGODB_URI);
} else {
mongoose.connect('mongodb://localhost/conduit');
mongoose.set('debug', true);
}
What is still wrong here ?

Answer 1

Firstly, you should run your mongodb image after that you should mount mongo container to app container while run your app container. For example,
docker run -p xxxx:xxxx --link mongo:mongo <image-name>
And to connect mongodb like this, you should use a connection string like below,
'mongodb://mongo:27017/<db-name>'