Docker platform variable expansion
Description
I like the relatively recently added feature to specify the docker platform when running an image. I would really like to use this with a parallel matrix to run a job for multiple arches. It looks like variable expansion is supported for the image:name field but not for the image:docker:platform field. I would like for variable expansion to be added here.
Proposal
As an example of what I'd like to do:
.base_job:
image:
name: ubuntu:24.04
docker:
# Is not presently supported
platform: $PLATFORM
my_job:
extends:
- .base_job
parallel:
matrix:
- PLATFORM: ["linux/amd64", "linux/arm64"]I looked at the code and I think it might be as easy as adding executors/docker/docker.go:expandAndGetDockerImage to have:
dockerOptions.Platform := e.ExpandValue(dockerOptions.Platform)
if err != nil {
return nil, err
}before the call to GetDockerImage.
I would be okay looking into making the change as a PR, but I'm not really sure how to build/test this.