Mongodb error on docker - mongodb

Question

I've a dockerfile and a docker-compose
When I try to run docker-compose this happens
Does someone know how to fix it?
Edit 1
dockerfile
FROM node
RUN apt-get update && apt-get install -y --no-install-recommends build-essential \
&& apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv EA312927 \
&& echo "deb http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 multiverse" | tee /etc/apt/sources.list.d/mongodb-org-3.2.list \
&& apt-get update \
&& apt-get install -y mongodb-org
RUN useradd --user-group --create-home --shell /bin/false app &&\
npm install --global npm
ENV HOME=/home/app
COPY package.json $HOME/library/
RUN chown -R app:app $HOME/*
USER root
WORKDIR $HOME/library
RUN npm install --silent --progress=false
COPY . $HOME/library
RUN chown -R app:app $HOME/*
RUN npm install --build-from-source bcrypt
CMD ["npm", "start"]
docker-compose
version: '2'
services:
db:
image: mongo
command: "mongod"
ports:
- "27018:27018"
library:
build:
context: .
dockerfile: Dockerfile
command: node_modules/.bin/nodemon --exec npm start
environment:
NODE_ENV: development
ports:
- 3000:3000
volumes:
- .:/home/app/library
- /home/app/library/node_modules
links:
- db
Edit 2
Running docker ps -a here
First container docker log here
Second container docker log here
Edit 3
mongoose.connect(config.database);
That's how I am connecting the database on server.js

Answer 1

Your Docker Compose file has the MongoDB Ports as 27018=>27018 but the error from your node application is saying it is trying to connect to 127.0.0.1:27017.
Because of how Docker's networking works (which is all kinds of awesome) you should change the port to be 27017 not 27018 in your Compose file & update the MongoDB connection string in your Node app to db:27017.
You shouldn't use 127.0.0.1 within Docker as it expects that whatever you are connecting to is running on within the same container.