🐳 Docker Compose

Work in progress

The documentation section is still a work in progress.

Using docker-compose.yml

Note that docker-compose.yml does not support default values evaluation in variables assignment. E.g.,

environment:
  VARIABLE2: ${VARIABLE1:-$VARIABLE3}

$VARIABLE3 will not be evaluated if $VARIABLE1 is not provided (it will be a literal string $VARIABLE3).

Validate docker-compose.yml

docker compose -f docker-compose.yml config

Host volume mounting in Docker-based projects

To share application code between services (containers), Docker uses volumes. When used in non-development environments, containers have access to the same shared files using volumes and these volumes do not need to be mounted from the host.

But for development environment, when the code constantly changes on the host, we need to have these changes synchronized into all containers. Since we are using single docker-compose.yml file for all environments, we have to accommodate both cases, so we are specifying an override for the same directory as a mounted volume as a commented-out lines, which will be automatically uncommented in CI.

See Docker Compose reference about volumes.