Running Multiple Containers Using Docker Compose

Docker Compose is used for running multiple containers and each of the containers run in isolation but can interact with each other when required. Docker Compose file are written in a scripting language called YAML.

We will use example-voting-app that we can find in dockersamples Github repository: https://github.com/dockersamples/example-voting-app

After cloning the repository, we have to build three applications since they are not available in Docker Hub: vote, worker, and result. To build them, run these three commands one by one:

docker build ./vote -t voting-app
docker build ./worker -t worker-app
docker build ./result -t result-app

After building those three applications, we can create a new docker-compose.yml file that containing the following script:

version: "3"
services:
    redis:
        image: redis
    
    db:
        image: postgres:9.4
        environment:
            POSTGRES_USER: postgres
            POSTGRES_PASSWORD: postgres

    vote:
        image: voting-app
        ports:
            - 5000:80
    
    worker:
        image: worker-app
    
    result:
        image: result-app
        ports:
            - 5001:80

We can then run docker-compose up command to run multiple containers.

To run voting-app we can go to localhost:5000 and to run result-app we can go to `localhost:5001”.

Source links:
Overview of Docker Compose