Docker-Compose - Communication with "Internal" Api. - angularjs

Question

I've developed an Angular App, that communicates with an UWSGI Flask Api throught Nginx. Currently I've 3 containers(Angular [web_admin], Api [api_admin], Nginx[nginx])
When I'm running it in my development machine, the communication is working alright. The angular requests goes through the url: http://localhost:5000 and the api response well, everything is working well.
But when I deployed it to my Production Server, I noticed that the application is not working, because the port 5000 is not opened in my firewall.
My question is kind simple, how do I make the angular container, call the api container, through internal network, instead of calling it from the external?
version: '2'
services:
data:
build: data
neo4j:
image: neo4j:3.0
networks:
- back
volumes_from:
- data
ports:
- "7474:7474"
- "7473:7473"
- "7687:7687"
volumes:
- /var/diariooficial/neo4j/data:/data
web_admin:
build: frontend/web
networks:
- front
- back
ports:
- "8001:8001"
depends_on:
- api_admin
links:
- "api_admin:api_admin"
volumes:
- /var/diariooficial/upload/diario_oficial/:/var/diariooficial/upload/diario_oficial/
api_admin:
build: backend/api
volumes_from:
- data
networks:
- back
ports:
- "5000:5000"
depends_on:
- neo4j
- neo4jtest
volumes:
- /var/diariooficial/upload/diario_oficial/:/var/diariooficial/upload/diario_oficial/
nginx:
build: nginx
volumes_from:
- data
networks:
- back
- front
ports:
- "80:80"
- "443:443"
volumes:
- /var/diariooficial/log/nginx:/var/log/nginx
depends_on:
- api_admin
- web_admin
networks:
front:
back:

Answer 1

Links create DNS names on the network for the services. You should have the web_admin service talk to api_admin:5000 instead of localhost:5000. The api_admin DNS name will resolve to the IP address of one of the api_admin service.
See https://docs.docker.com/compose/networking/ for an explanation, specifically:
Each container can now look up the hostname web or db and get back the appropriate container’s IP address. For example, web’s application code could connect to the URL postgres://db:5432 and start using the Postgres database.