connecting to local mongodb from docker container

Question

I have a local mongoDB server running on mongodb://127.0.0.1:27017. My DB name is localv2 . I have a node/express app with the Dockerfile as follows:

FROM node:7.5

RUN npm install -g pm2

RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

COPY package.json /usr/src/app
RUN npm install

COPY . /usr/src/app

EXPOSE 3002

ENV NODE_ENV local

CMD pm2 start --no-daemon server.js

The server.js file has a connection to local mongodb with the following code:

app.db = mongoose.connect("mongodb://127.0.0.1:27017/localv2", options);

This doesn't work when I spin up a container from the image created using the Dockerfile above. I read somewhere that Docker creates a VLAN with a gatway IP address of its own. When I docker inspect my container, my gateway IP address: 172.17.0.1.

Even on changing the mongodb connection to

app.db = mongoose.connect("mongodb://172.17.0.1:27017/localv2", options)

and re-building the image and starting a new container, I still get the error:

MongoError: failed to connect to server [172.17.0.1:27017] on first connect [MongoError: connect ECONNREFUSED 172.17.0.1:27017]

Command to run the container: docker run -p 3002:3002 image-name

Please help.

Answer 1

Adding @vlad-holubiev as answer here because it has worked for me and help users to find it.

Using the network host option on docker run , as specified in the docs:

With the network set to host a container will share the host's network stack and all interfaces from the host will be available to the container. The container's hostname will match the hostname on the host system.

docker run -d -e ROOT_URL=http://localhost -e MONGO_URL=mongodb://localhost:27017 --network="host"

Answer 2

On Docker for Mac, you can use host.docker.internal if your mongo is running on your localhost. You could have your code read in an env variable for the mongo host and set it in the Dockerfile like so:

ENV MONGO_HOST "host.docker.internal"

See here for more details on https://docs.docker.com/docker-for-mac/networking/#use-cases-and-workarounds

Answer 3

A docker container is a separate from your computer,
So you will not be able to connect to your localhost .
You should run the mongo server on a container and the connect with the image name.

mongodb://CONTAINER-NAME:port

Answer 4

Create .env file such as:

DB_HOST=myMongoServiceIp
DB_USER=myMongoDBUser
DB_PORT=myMongoServicePort
DB_PASSWORD=myMongoDBPort
DB_AUTH_NAME=myMongoDBAuthDatabase
DB_CONNECT_NAME=myStartDBConnection

If you have already a MongoDB Service in your local machine just replace the DB_HOST to host.docker.internal . This is special DNS name only, which resolves to the internal IP address used by the host. Of course, you need to replace the DB_HOST with the proper IP of the Server when running in Prod Mode.

Finally, the Localhost example .env :

DB_HOST=host.docker.internal
DB_USER=app1
DB_PORT=27017
DB_PASSWORD=123
DB_AUTH_NAME=admin
DB_CONNECT_NAME=test

If your app was written in with Mongoose, for example, the mongodb connection string might be something like:

var mongoConnectionString = `mongodb://${process.env.DB_USER}:${process.env.DB_PASSWORD}@${process.env.DB_HOST}:${process.env.DB_PORT}/${process.env.DB_CONNECT_NAME}?authSource=${process.env.DB_AUTH_NAME}`

Ultimately, to run the docker container now, all you need to do is add your .env file on it, such as:

docker run --env-file .\src\.env --name MyContainer -dp 8080:8080 <myUser>/<repo>:<tagname>

Then you have a container using your local MongoDB instead of another container.