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

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 2

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"