Two apps with different port in single docker-compose and nginx reverse proxy

Question

I have an app running with app.dev domain in my localhost. However, I would want to have an additional app running with a different port. Instead of port 80, it would be 2000 with domain app.dev:2000 at app2. What changes should I make to my docker-compose and nginx?

This is my docker-compose:

version: "2"

volumes: 
  mongostorage:

services:
  app:
    build: ./app
    ports:
      - "3000"
    links:
      - mongo
      - redis
    command: node ./bin/www
  app2:
    build: ./app2
    ports:
      - "2000"
    links:
      - mongo
      - redis
    command: node app.js
  nginx:
    build: ./nginx
    ports:
      - "80:80"
    links:
      - app:app
  mongo:
    image: mongo:latest
    environment:
      - MONGO_DATA_DIR=/data/db
    volumes:
      - mongostorage:/data/db
    ports:
      - "27017:27017"
  redis:
    image: redis
    volumes:
      - ./data/redis/db:/data/db
    ports:
      - "6379:6379"

This is my nginx.conf

events {
  worker_connections  1024;
}

http{
    upstream app.dev{
        least_conn;
        server app:3000 weight=10 max_fails=3 fail_timeout=30s;
    }

    server {
        listen 80;
        server_name app.dev;

        location / {
            proxy_pass http://app.dev;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
        }
    }
}

Answer 1

I think just changing the ports of app2 in the following way should be enough, as nginx only listens to port 80.

app2:
  build: ./app2
  ports:
    - "2000:2000"
  links:
    - mongo
    - redis
  command: node app.js

Answer 2

The simplest way is to expose app2 on port 2000

  app2:
    build: ./app2
    ports:
      - '2000:2000'

The other is to route the connection via nginx, to be consistent with the first app.

Compose

  nginx:
    build: ./nginx
    ports:
      - '80:80'
      - '2000:2000' 

Nginx

http{
    upstream app.dev{
        least_conn;
        server app:3000 weight=10 max_fails=3 fail_timeout=30s;
    }
    upstream app2.dev{
        least_conn;
        server app2:2000 weight=10 max_fails=3 fail_timeout=30s;
    }

    server {
        listen 80;
        server_name app.dev;

        location / {
            proxy_pass http://app.dev;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
        }
    }
    server {
        listen 2000;
        server_name app.dev;

        location / {
            proxy_pass http://app2.dev/;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
        }
    }
}

By the way you don't need any of the links in a version 2+ compose file. You already have access to all the services via the service name.