Reach Docker container from other docker Container within localhost:port - docker

Question

Current compose yaml:
version: '3.7'
networks:
app-tier:
driver: bridge
services:
php:
container_name: docker_php
build: .docker/php73
volumes:
- .:/srv/
networks:
- app-tier
rabbitmq:
container_name: docker_rabbitmq
image: "rabbitmq:3-management"
hostname: "rabbitmq-localhost"
environment:
RABBITMQ_DEFAULT_USER: guest
RABBITMQ_DEFAULT_PASS: guest
ports:
- "15672:15672"
- "5672:5672"
networks:
- app-tier
My target is to reach docker_rabbitmq container from docker_php within localhost:
#bash php_container
telnet loaclhost 15672
How can I configure a network that:
container A has port mapping on localhost to Container B?

Answer 1

you're limited by the inner port, which means if your two containers are in the same docker defined network, you can use the internally opened ports of the respective container. For the hostname to be defined for a container in a different one, you can use the links attribute in the service definition inside your docker-compose.yml.
Consider a micro service which you want to be only accessed by only the containers on that network therefore exposing the ports on the host wouldn't make sense. Now assuming rabbitmq is the service that you want to access from php service, you need to define a link to rabbitmq in your php service definition( please not the link/host-definition is not bi-directional, if you need php in your rabbitmq you need to define a link in rabbitmq for php)
version: '3.7'
networks:
app-tier:
driver: bridge
services:
php:
container_name: docker_php
build: .docker/php73
volumes:
- .:/srv/
networks:
- app-tier
links:
- rabbitmq
rabbitmq:
container_name: docker_rabbitmq
image: "rabbitmq:3-management"
hostname: "rabbitmq-localhost"
environment:
RABBITMQ_DEFAULT_USER: guest
RABBITMQ_DEFAULT_PASS: guest
networks:
- app-tier
Now you can access the internal ports of the rabbitmq from php but note the expternal ports are not accessible, those are for the host.
# inside your `php` container `bash`
telnet rabbitmq <internal_port>
Also not that I got rid of the ports in rabbitmq by removing
now these ports of rabbitmq are not accessible from the host.
Update
if you want to access the ports, such that the ports opened in rabbitmq are accessible in php on localhost. the easiest and the simplest way would be to configure rabbitmq to run in container network mode on the network of php to do this simple add
network_mode: "container:[container name/id]"
rabbitmq:
container_name: docker_rabbitmq
image: "rabbitmq:3-management"
hostname: "rabbitmq-localhost"
environment:
RABBITMQ_DEFAULT_USER: guest
RABBITMQ_DEFAULT_PASS: guest
network_mode: "container:php"
ports:
- "15672:15672"
- "5672:5672"