Docker-compose Nodejs Mongodb doesn't success - node.js

Question

I am testing NodeJS + MongoDB on local Mac OS with docker-compose, but NodeJS and MongoDB can't connect successfully.
If I didn't setup --auth for MongoDB by below code, all works well.
Here's the code:
mongoose connection
mongodb://mongodb:27017/myprojectdatabase
docker-compose.yml
version: "3"
services:
web:
build: .
restart: always
ports:
- "8080:8080"
depends_on:
- mongodb
volumes:
- .:/mycode
mongodb:
image: mongo:latest
ports:
- "27017:27017"
Then I want to start --auth for the MongoDB like below, I got errors.
docker-compose.yml
version: "3"
services:
web:
build: .
restart: always
ports:
- "8080:8080"
depends_on:
- mongodb
volumes:
- .:/mycode
# environment:
# - NODE_ENV=production
mongodb:
image: mongo:latest
command: [--auth]
environment:
MONGO_INITDB_ROOT_USERNAME: my_admin
MONGO_INITDB_ROOT_PASSWORD: my2019
MONGO_INITDB_DATABASE: myprojectdatabase
ports:
- "27017:27017"
volumes:
- ./mydata:/data/db
Then I run
docker-compose down -v && docker-compose up --build
I got the output:
mongodb_1 | 2019-03-01T10:54:09.847+0000 I CONTROL [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] MongoDB starting : pid=1 port=27017 dbpath=/data/db 64-bit host=9554854909b1
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] db version v4.0.4
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] git version: f288a3bdf201007f3693c58e140056adf8b04839
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.0.2g 1 Mar 2016
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] allocator: tcmalloc
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] modules: none
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] build environment:
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] distmod: ubuntu1604
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] distarch: x86_64
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] target_arch: x86_64
mongodb_1 | 2019-03-01T10:54:09.869+0000 I CONTROL [initandlisten] options: { net: { bindIpAll: true }, security: { authorization: "enabled" } }
mongodb_1 | 2019-03-01T10:54:09.873+0000 W STORAGE [initandlisten] Detected unclean shutdown - /data/db/mongod.lock is not empty.
mongodb_1 | 2019-03-01T10:54:09.876+0000 I STORAGE [initandlisten] Detected data files in /data/db created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
mongodb_1 | 2019-03-01T10:54:09.878+0000 W STORAGE [initandlisten] Recovering data from the last clean checkpoint.
mongodb_1 | 2019-03-01T10:54:09.879+0000 I STORAGE [initandlisten] wiredtiger_open config: create,cache_size=487M,session_max=20000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),statistics_log=(wait=0),verbose=(recovery_progress),
web_1 | connection error: { MongoNetworkError: failed to connect to server [mongodb:27017] on first connect [MongoNetworkError: connect ECONNREFUSED 192.168.160.2:27017]
web_1 | at Pool.<anonymous> (/usr/src/app/node_modules/mongodb-core/lib/topologies/server.js:505:11)
web_1 | at emitOne (events.js:116:13)
And some times I can see the log contains the user created information, sometimes are not.
2019-03-01T10:38:50.323+0000 I STORAGE [conn2] createCollection: admin.system.users with generated UUID: 6b3b88f9-e77c-4094-a1c7-153816202a9e
mongodb_1 | Successfully added user: {
mongodb_1 | "user" : "my_admin",
mongodb_1 | "roles" : [
mongodb_1 | {
mongodb_1 | "role" : "root",
mongodb_1 | "db" : "admin"
mongodb_1 | }
mongodb_1 | ]
mongodb_1 | }
mongodb_1 | 2019-03-01T10:38:50.340+0000 E - [main] Error saving history file: FileOpenFailed: Unable to open() file /home/mongodb/.dbshell: Unknown error
I am new on docker stuff. I guess the main problem is web can't establish a connection with mongodb. Spend too long on this problem.
Any help? Thanks!

Answer 1

Make sure you're not going to localhost of the web container. Treat containers as separate machines: localhost in one container is not shared with another one. That's why in the connection string you have mongodb:27017 and not localhost:27017, because mongodb in your default docker network is a DNS name of the container with mongo. You are using this connection string in the first (successful) case, make sure you have a valid DNS name in the second one.
And also make sure to include your DB credentials (username:password) in the connection string too.