Docker Compose

• Why: configure relationships between containes

• Why: save our docker container run settings in easy-to-read file

• Why: create one-liner developer environment startups

• Comprised of 2 seperate but related things

  1. YAML-formatted file that describes our solution options for:

     • containers
     • networks
     • volumes

  2. A CLI tool docker-compose used for local dev/test automation with those YAML files

docker-compose.yml

• Compose YAML format has it's own versions: 1, 2, 2.1, 3, 3.1
• YAML file can be used with docker-compose command for local docker automation or...
• With docker directly in production with Swarm (as of v1.13)
• docker-compose --help
• docker-compose.yml is default filename, but any can be used with docker-compose -f

docker-compose CLI

• CLI tool comes with Docker for WIndows/Mac, but separate download for Linux

• Not a production-grade tool but ideal for local development and test

• Two most common commands are

  • docker-compose up - setup volumes/networks and start all containers
  • docker-compose down - stop all containers and remove cont/vol/net

• If all your projects had a Dockerfile and docker-compose.yml then "new developer onboarding" would be:

  • git clone github.com/some/software
  • docker-compose up

Use Compose to Build

• Compose can also build your custom images
• WIll build them with docker-compose up if not found in cache
• Also rebuild with docker-compose build
• Great for complex builds that have lots of vars or build args