Docker container 'Connect ECONNREFUSED localhost'

Question

I am running a simple Nodejs application with 2 containers. A server container and a client. I have a setup so that when the client makes a request to the server, it streams some data back to the client, however when I try to make this request from the client, I receive the following error

connect ECONNREFUSED 127.0.0.1:8080

This is also the case when I use the containers IP address. Both containers are on the same network. I confirmed this with docker network inspect. When I make the same request via Postman, it works fine.

Here is my setup

Server Setup

Server Dockerfile

FROM node:12
EXPOSE 8080
WORKDIR /home/node/server
COPY package*.json ./
RUN npm install
COPY . .
CMD ["node", "app.js"]

Server http function

http.createServer(function(request, response){
    filePath = path.join("./serverdata", 'filename.txt');
    var stat = fs.statSync(filePath);

    response.writeHead(200, {
        'Content-Type': 'text/plain',
        'Content-Length': stat.size
    });

    var readStream = fs.createReadStream(filePath);
    readStream.pipe(response);
})
.listen(port);

Client Setup

Client Dockerfile

FROM node:12
WORKDIR /home/node/client
COPY package*.json ./
RUN npm install
COPY . .
CMD ["node", "capp.js"]

Client Get Function NB using the server container IP yielded same results

http.get('http://localhost:8080', (resp)=>{
    let data = '';

    resp.on('data', (chunk)=>{
        data += chunk;
    });

    resp.end('end', ()=>{
        console.log(data);
    });
}).on("error", (err)=>{
    console.log(err.message);
});

Docker Compose

version: "3.2"

services:
  server-app:
    build: ./serverClient
    ports: 
      - 8080:8080
    volumes:
      - servervol:/serverdata

  client-app:
    build: ./clientClient
    ports:
      - 8081:8081
    volumes:
      - clientvol:/clientdata
    depends_on:
      - "server-app"

volumes:
  servervol:
    driver: local
  clientvol:
    driver: local

I have read a few posts proclaiming that the issue is with using localhost instead of the container IP, but I have tried both with no success. As mentioned, when done in Postman, it works fine; this leads me to think that the issue is with the client part. Any guidance is much appreciated.

Thanks

Answer 1

Since you are using Docker Compose, by default (because you didn't specify network) your services share the same (default) network, and therefore you can use the name of the service instead of its IP address to communicate with it because Docker can figure out the IP address based on service name due to service name resolution.

And because of all that Docker magic, the only thing you need to change is the way you connect to server:

http.get('server-app:8080', (resp) => { ... })