support "extends" keyword

[fommil]

What needs to be done in order to support the extends keyword? We have all our docker compose files under a directory and it would be really messy to explicitly copy/paste everything.

[kurtkopchik]

Hi @fommil, the plugin currently reads the specified docker-compose.yml file into memory, performs some processing on it and then writes out a new version which is ultimately used when the docker-compose instance is started.

To support the extends keyword the readComposeFile code would have to be updated to:

1. Follow the linked compose files specified in extends
2. Merge the contents of those files with the base compose file (I imagine there will be a number of complexities to handle in this step which is why support for this keyword has not yet been added)
3. Return a representation of the merged compose files for processing

That being said, there is a composeFile setting that can be defined on a per-project basis were you can point the project to use an existing compose file at a location and name of your choosing without having to explicitly copy it into the project:
composeFile := // Specify the full path to the Compose File to use to create your test instance. It defaults to docker-compose.yml in your resources folder.

Is this something that can work for your use case?

[fommil]

We're using composeFile already but I hit the error saying that extends is not supported (it extends from another file in the same directory).

[kurtkopchik]

To support the extends feature in docker compose files the plugin code would need to be updated to add the functionality outlined above. I hope to implement this myself in the future but PR's are certainly welcome :)