Docker bridge network between stacks

In this guide, I will explain how to connect two containers in different docker-compose.yml Services together that are setup on the same host machine.

By default every docker-compose.yml Service is generating its own bridge-Network so that containers inside can communicate between each other.

But communications between two docker-compose.yml Services on the same host machine are blocked by docker. So we need to create a new "custom" bridge-Network if two containes in different docker-cmpose.yml Services need to communicate between each other.

In this example I want to connect web-app1 container with the DB2 container from different docker-compose.yml Services.

More information about this topic can be found on the offical docker documentation: https://docs.docker.com/compose/networking

We need to create the custom bridge-Network:

For the custom bridge-Network you can use your own name. In my example I chose the name serv1_link_serv2

sudo docker network create -d bridge serv1_link_serv2

Now create the two docker-compose.yml files and connect web-app1- and db2-container together over the serv1_link_serv2bridge-Network.

docker-compose1.yml

version: "3"
services:
 db1:
   image: "mariadb:latest"
   ........

 web-app1:
   image: "php:apache"
   ........
   networks:
     - serv1_link_serv2
     - default

networks:
 serv1_link_serv2
   name: serv1_link_serv2
   external: true

docker-compose2.yml

version: "3"
services:
 db2:
   image: "mariadb:latest"
   ........
   networks:
     - serv1_link_serv2
     - default

 web-app2:
   image: "php:apache"
   ........

networks:
 serv1_link_serv2
   name: serv1_link_serv2
   external: true