Running different docker containers on same host/different port - ruby-on-rails

Question

I have an app composed of multiple rails projects, I am trying to dockerize them, each app starts on a different rails port :
main app: 1665
admin: 3002
website: 3000
...
This is my docker-compose.yml file :
version: '2'
services:
db:
image: postgres:9.6
container_name: acme_db
hostname: db.myapp.dev
hostname: db.ach
ports:
- "5432:5432"
volumes:
- myapp_pgdata:/var/lib/postgresql/data/pgdata
environment:
- PGDATA=/var/lib/postgresql/data/pgdata
- VIRTUAL_HOST=db.myapp.dev
networks:
- generic
myapp:
image: acme/myapp
container_name: acme_myapp
hostname: app.myapp.dev
command: rails s -p 1665 -b '0.0.0.0'
volumes:
- ./myapp:/usr/src/app
- $SSH_AUTH_SOCK:/tmp/ssh_auth_sock
ports:
- "1665:1665"
depends_on:
- db
environment:
- SSH_AUTH_SOCK=/tmp/ssh_auth_sock
- RAILS_ENV=development
- VIRTUAL_HOST=myapp.dev
networks:
- generic
admin:
image: acme/admin
container_name: acme_admin
hostname: admin2.myapp.dev
command: rails s -p 3002 -b '0.0.0.0'
volumes:
- ./admin2:/usr/src/app
- $SSH_AUTH_SOCK:/tmp/ssh_auth_sock
ports:
- "3002:3002"
depends_on:
- myapp
environment:
- SSH_AUTH_SOCK=/tmp/ssh_auth_sock
- RAILS_ENV=development
- VIRTUAL_HOST=admin2.myapp.dev
networks:
- generic
website:
image: acme/website
container_name: acme_website
hostname: web.myapp.dev
command: rails s -p 3001 -b '0.0.0.0'
volumes:
- ./website:/usr/src/app
- $SSH_AUTH_SOCK:/tmp/ssh_auth_sock
ports:
- "3001:3001"
environment:
- SSH_AUTH_SOCK=/tmp/ssh_auth_sock
- RAILS_ENV=development
- VIRTUAL_HOST=myapp.dev
networks:
- generic
volumes:
myapp_pgdata:
external: true
networks:
generic:
external: true
Running each app works fine, but I have a problem when applications need to communicate between them, for instance the website need to forward an http request to the main app, and when it does, it tries to resolve this uri: http://app.myapp.dev:1665/register and, the resolved ip is 127.0.0.1 instead of the myapp docker container ip.
How can I manage this situation ? Should I use completely different hostnames for each container ? Ideally I would like to avoid DNS resolution so rails tries to hit app.myapp.dev:1665 instead of resolving app.myapp.dev and then resolving 127.0.0.1:1665
btw, I am using jwilder/nginx-proxy to resolve containers hostnames from my laptop.
Any thoughts ?

Answer 1

Your setup allows your containers to resolve each other by their names through the 'network' set up by docker-compose.
So website should be able to hit the main app through http://myapp:1665/register