Docker Compose supports extending a compose file for different environments or different workflows.
This allows you to share common configuration and minimise the risk of configurations going out of sync.
Here we look at extending an entire Compose file by using multiple Compose files.
If we look at docker-compose.yml and docker-compose.old-way.yml we can see they both use the express-app service, with old-way adding some additional configuration.
As seen in dockerizedCodeceptJSPuppeteer the command
docker-compose -f docker-compose.old-way.yml run --rm codeceptjs-container
would be used to run the file for testing.
Using composition we can make the code more DRY. As seen in docker-compose.new-way.yml we simply layer on top of docker-compose.yml and only add the new service information.
We can then run new-way using:
docker-compose -f docker-compose.yml -f docker-compose.new-way.yml run --rm codeceptjs-container
This is optional, and not included in the other examples to introduce concepts one at a time, but recommended.