Simple Networking with Docker-Compose

It’s one thing to create networks manually, but another thing to use them inside docker-compose. In this lecture I want to create a simple network and use it in docker-compose. Let’s dive right in and see how that works!

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Understanding, creating and using networks in docker-compose.yml

This exercise is here to showcase a typical network configuration and segregation using docker-compose.yml. There are service-level and top-level network definitions. The service level is for “which network does this service join”. The top-level for “how does the network look like”. Let’s use this docker-compose.yml file:

version: "3.7"
 
services:
 
  app1:
    image: httpd:latest
    container_name: app1
    ports:
     - 8080:80
    networks:
      - app1_net
 
networks:
  app1_net:
 

• Creates one network called “app1_net”
  • top-level, last line, without any further configuration. This will be a bridge network.
• Attaches container app1 to the network

docker-compose up

• Starts the container

Open http://localhost:8080  in a browser and bbserve the output. Then in a second Terminal window get the docker container infos:

docker ps

• Get the currently running containers

docker inspect app1

• Observe the networking part!

Close the second terminal with exit

Back to terminal 1:

ctrl+c

• Stops the docker-compose

docker-compose down

• cleanup