Unable to connect nodejs app to mongodb using docker-compose - node.js

Question

Simple Node app and mongo containers created using docker-compose below... What am I missing?
mongodb://user:password#mongo:27017/
version: '3.8'
services:
mongo:
image: mongo
restart: always
environment:
- MONGO_INITDB_ROOT_USERNAME=user
- MONGO_INITDB_ROOT_PASSWORD=password
app:
image: app
build:
context: ./app
dockerfile: Dockerfile
ports:
- "3000:3000"
depends_on:
- mongo
I've read several posts on the same issue and the official mongo docker page and seem to be doing everything correct. Keep getting the following msg.
app_1 | mongodb://user:password#mongo:27017/ {
app_1 | autoIndex: false,
app_1 | poolSize: 10,
app_1 | bufferMaxEntries: 0,
app_1 | useNewUrlParser: true,
app_1 | useUnifiedTopology: true
app_1 | }
app_1 | MongoDB connection with retry
app_1 | MongoDB connection unsuccessful, retry after 5 seconds. 2

Answer 1

I prepared interesting test for you
version: '3.8'
services:
mongo:
image: mongo
environment:
- MONGO_INITDB_ROOT_USERNAME=user
- MONGO_INITDB_ROOT_PASSWORD=password
healthcheck:
test: "echo 'db.runCommand(\"ping\").ok'"
interval: 5s
timeout: 5s
retries: 3
app:
image: mongo
command: "mongosh mongodb://user:password#mongo:27017/admin --eval \"printjson(db.test.insertOne({'a': 1}))\""
ports:
- "3000:3000"
depends_on:
- mongo
It will print
app_1 | {
app_1 | acknowledged: true,
app_1 | insertedId: ObjectId("63696c4e99703eb4ab9fba62")
app_1 | }
but if you will change
command: "mongosh mongodb://user:password#mongo:27017/admin --eval \"printjson(db.test.insertOne({'a': 1}))\""
to
command: "mongosh mongodb://user:password#mongo:27017/local --eval \"printjson(db.test.insertOne({'a': 1}))\""
you will see error. Even if you will add MONGO_INITDB_DATABASE to mongo with value local.
You can test it running in second console command:
docker-compose run app bash
and then try
mongosh mongodb://user:password#mongo:27017/admin --eval "printjson(db.test.insertOne({'a': 1}))"
with success
and
mongosh mongodb://user:password#mongo:27017/local --eval "printjson(db.test.insertOne({'a': 1}))"
that failing. You can see logs from mongo like
mongo_1 | {"t":{"$date":"2022-11-07T20:40:35.686+00:00"},"s":"I", "c":"ACCESS", "id":20249, "ctx":"conn6","msg":"Authentication failed","attr":{"mechanism":"SCRAM-SHA-256","speculative":true,"principalName":"user","authenticationDatabase":"local","remote":"172.20.0.3:50382","extraInfo":{},"error":"UserNotFound: Could not find user \"user\" for db \"local\""}}
mongo_1 | {"t":{"$date":"2022-11-07T20:40:35.687+00:00"},"s":"I", "c":"ACCESS", "id":20249, "ctx":"conn6","msg":"Authentication failed","attr":{"mechanism":"SCRAM-SHA-1","speculative":false,"principalName":"user","authenticationDatabase":"local","remote":"172.20.0.3:50382","extraInfo":{},"error":"UserNotFound: Could not find user \"user\" for db \"local\""}}
mongo_1 | {"t":{"$date":"2022-11-07T20:40:35.688+00:00"},"s":"I", "c":"NETWORK", "id":22944, "ctx":"conn5","msg":"Connection ended","attr":{"remote":"172.20.0.3:50374","uuid":"b77fff1f-b832-4900-9c2d-1e7fd1e79424","connectionId":5,"connectionCount":1}}
mongo_1 | {"t":{"$date":"2022-11-07T20:40:35.699+00:00"},"s":"I", "c":"NETWORK", "id":22944, "ctx":"conn6","msg":"Connection ended","attr":{"remote":"172.20.0.3:50382","uuid":"3995bcbf-706d-4bed-92a2-04736305b7c2","connectionId":6,"connectionCount":0}}
this problem is described in topic User not found on MongoDB Docker image with authentication
You can authenticate with user,password against admin db, not mydb
You can read more about creating database with user and password here:
How to create a DB for MongoDB container on start up?