How to connect nodeJS docker container to mongoDB - node.js

Question

I have problems to connect a nodeJS application which is running as a docker container to a mongoDB. Let me explain what I have done so far:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3a3732cc1d90 mongo:3.4 "docker-entrypoint..." 3 weeks ago Up 3 weeks 27017/tcp mongo_live
As you can see, there is already a mongo docker container running.
Now I'm running my nodeJS application docker container (which is a build from meteorJS):
$ docker run -it 0b422defbd59 /bin/bash
In this docker container I want to run the application by running:
$ node main.js
Now I'm getting the error
Error: MONGO_URL must be set in environment
I already tried to set MONGO_URL by setting:
ENV MONGO_URL mongodb://mongo_live:27017/
But this doesn't work:
MongoError: failed to connect to server [mongo_live:27017] on first connect
So my question is how to connect to a DB, which is - as far as I understand - 'outside' of the running container. Alternativly how do I set up a new DB to this container?

Answer 1

There are couple of ways to do it.
run your app in the same network as your mongodb:
docker run --net container:mongo_live your_app_docker_image
# then you can use mongodb in your localhost
$ ENV MONGO_URL mongodb://localhost:27017/
Also you can link two containers:
docker run --link mongo_live:mongo_live you_app_image ..
# Now mongodb is accessible via mongo_live
use mongodb container ip address:
docker inspect -f '{{.NetworkSettings.IPAddress}}' mongo_live
# you will get you container ip here
$ docker run -it 0b422defbd59 /bin/bash
# ENV MONGO_URL mongodb://[ip from previous command]:27017/
You can bind your mongodb port to your host and use host's hostname in your app
You can use docker network and run both apps in the same network
You could pass --add-host mongo_live:<ip of mongo container> to docker run for your application and then use mongo_live for mongodb url
You can also use docker compose to make your life easier ;)
...

Answer 2

When you run containers each container works in independent network. Because one container cant connect to other point to point.
The are 3 ways to connect containers
Have a little fuss with low-level docker network magic
Connect container through localhost. Each container must expose ports on localhost (as your mongo_live). But you need add to host ile on localhost 127.0.0.1 mongo_live (This is the simplest way)
Use docker-compose. It convenient tool for working many containers together. (This is right way)
Add mongodb to application container is not docker way.

Answer 3

Please use below snippet for your docker-compose.yml file, replace comments with your actuals. Should solve your problem.
version: '2'
services:
db:
build: <image for mongoDB>
ports:
- "27017:27017" # whatever port u r using
environment:
#you can specify mondo db username and stuff here
volumes:
- #load default config for mondodb from here
- "db-data-store:/data/db" # path depends on which image you use
networks:
- network
nodejs:
build: #image for node js
expose:
- # mention port for nodejs
volumes:
- #mount project code on container
networks:
- network
depends_on:
- db
networks:
network:
driver: bridge
Please use the below links for references :
1) NodeJs Docker
2) MongoDb docker
3) docker-compose tutorial
Best of Luck

Answer 4

I had problem how to connect my server.js to mongodb. And that's how i solved it hope you find it useful.
Tap For My Screenshot