Docker Compose

Definition

Docker Compose is a tool that was developed to help define and share multi-container applications.

• Docker Desktop will group running containers in tabs of different applications (same as folder name in which docker-compose.yml is located).

resources

• awesome-compose collects great docker-compose files for common App setups.

docker compose file

Docker Compose is a tool for defining and running multi-container Docker applications.

1. Define a docker-compose.yml file, e.g.

   version: "2"
   
   services:
     voting-app:
       build: ./voting-app/.
       volumes:
        - ./voting-app:/app
       ports:
         - "5000:80"
       links:
         - redis
       networks:
         - front-tier
         - back-tier
   
     result-app:
       build: ./result-app/.
       volumes:
         - ./result-app:/app
       ports:
         - "5001:80"
       links:
         - db
       networks:
         - front-tier
         - back-tier
   
     worker:
       image: manomarks/worker
       links:
         - db
         - redis
       networks:
         - back-tier
   
     redis:
       image: redis:alpine
       ports: ["6379"]
       networks:
         - back-tier
   
     db:
       image: postgres:9.4
       volumes:
         - "db-data:/var/lib/postgresql/data"
       networks:
         - back-tier
   
   volumes:
     db-data:
   
   networks:
     front-tier:
     back-tier:

2. Launch your app. In the same directory as your .yml file:

   docker-compose up -d

New: compose is now a built-in docker command

docker compose up -d

links

With

links:
  - db

the container will wait for the db container to finish building

profiles

1. Add certain containers in your docker-compose.yml file to a profile.
2. When running docker-compose that container will only be launched if --profile {profile_name} is added.

e.g. docker-compose --profile my_profile up will only run the container which has the following attribute:

 profiles:
      - my_profile

Troubleshooting

If docker-compose up throws errors, some cached files might cause trouble. Run:

docker-compose build

This runs the Dockerfile for sure even if stuff is cached in the case of docker-compose up.

Live Server vs. Development docker-compose.yml file

your docker-compose file:

Live

services:
  my_app:
  	image: my_dockerhub_account/my_app
  	...

Dev on localhost

services:
  my_app:
  	build: .
  	volumes:
     - ./my-app:/app
  	...