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Docker compose

is useful:

  • when you need to start multiple containers which work together
  • it automatically creates shared network
  • parameters are saved in a file instead of multiple positional arguments on multiple docker run commands
  • when your software runs on a single host and you do not want to bother with kubernetes

install

Offcial

sudo curl -L "https://github.com/docker/compose/releases/download/1.25.5/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

sudo chmod +x /usr/local/bin/docker-compose

usage cli

# start container in backround
docker-compose up -d 

# remove containers, network and (unnamed) volumes
docker-compose down 

# remove containers, networks and volumes
docker-compose down -v

# show logs of services
docker-compose logs -f

# if a new image for a service is avaiable update it
docker-compose up -d --force-recreate

# or with
docker-compose pull
docker-compose restart

usage docker-compose.yml

Docker compose file reference

  • image reference a docker image for the service
  • build build a docker image for the service (usage instead of image)
  • command Override the default command of the docker image of the service
  • container_name set a specific container name (without one would be generated <imageName>-<serviceName>)
  • restart defaults to no. Other options are: always, on-failure, unless-stopped
  • environment: to define a list of environment variables. Boolean values need to be quoted so the yaml parser does not interfere
  • volumes can be defined on service level or shared for every container on root level of the yaml see.There is a long form where you can configure more things and a short form which works similar to the usual -v flag in docker run: [SOURCE:]TARGET[:MODE].

noteworthy

By default Docker compose searches for a ./docker-compose.yml file - By default Compose sets up a single network for your app, so that the containers can communicate with each other by their container name. - Valid top-level sections for a Compose file are: version, services, networks, volumes, and extensions starting with "x-"