How do i get my two docker containers to communicate with each other?

Question

How do I get my two docker containers to communicate with each other on Localhost?

I have separated out my project into a backend and a front-end. I am now trying to run both parts in separate docker containers however i get a connection refused. I tried running both on a docker network but it didn't seem to work.

Both my Dockerfiles look like

COPY ./build/libs/demo-0.0.1-SNAPSHOT.jar /usr/app/

WORKDIR /usr/app

RUN sh -c 'touch demo-0.0.1-SNAPSHOT.jar'

RUN apk add --update \
    curl \
    && rm -rf /var/cache/apk/*

ENTRYPOINT ["java","-jar","demo-0.0.1-SNAPSHOT.jar"]

and the front end makes calls to the back end by

protected <T> ResponseEntity<T> getRequest(String path, Class<T> responseType) {
        return restTemplate.getForEntity("http://localhost:8090/" + path, responseType);
    }

but i get a

java.net.ConnectException: Connection refused (Connection refused)

I run both my container via:

docker run -p 8090:8090 -d repo/back-end
docker run -p 8080:8080 -d repo/front-end   

Answer 1

In docker you can create your own network:

docker network create myNetwork

And run containers inside this network using --net and --name flags:

docker run -d -p 8000:8000 --net myNetwork --name backend backend-image
docker run -d -p 8001:8001 --net myNetwork frontend-image

Then you should be able to access backend using http://backend:8000 url from your frontend container.

Answer 2

Thanks both for the responses, i added a docker-compose.yml in frontend

version: '3'
services:
  frontend:
    build: .
    ports:
      - "8080:8080"
networks:
  default:
    external:
      name: myNetwork

and in backend

version: '3'
services:
  backend:
    build: .
    ports:
      - "8090:8090"
networks:
  default:
    external:
      name: myNetwork

and then changed my rest service to make calls to

private static final String prefix = "http://backend:8090/";