connecting to local mongodb from docker container

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.

via chaudharyp