Support cross-building / buildx

[LeifW]

We want to publish Docker images for both x64 and arm64. Looks like sbt-native-packager added this in sbt/sbt-native-packager#1527 - seems to mostly be a matter of shelling out to docker buildx instead of docker build, with some other args?

[andrewhibbert]

If you run docker buildx install docker build will alias to docker buildx build. You'd then need to pass in flag of platform like this:

docker / buildOptions := BuildOptions(
  cache                        = false,
  removeIntermediateContainers = BuildOptions.Remove.Always,
  pullBaseImage                = BuildOptions.Pull.Always,
  additionalArguments          = Seq("--platform", "linux/amd64,linux/arm64")
)

Prior to this you need QEMU binaries you can get this via docker:

docker run --privileged --rm tonistiigi/binfmt --install all

And you'll need to setup and use a new instance:

docker buildx create --name multiarch --driver docker-container
docker buildx use --default --global multiarch

It is best to use --push in additionalArguments, but then you also need to tag it -t <repo:tag> and additionalArguments seems to only support strings

[nik-kashi]

Hi @andrewhibbert
Thanks for the solution, but after applying these changes to my code I receive an error from the sbt-docker plugin which Could not parse Docker image id
related to this line: https://github.com/marcuslonnberg/sbt-docker/blob/master/src/main/scala/sbtdocker/DockerBuild.scala#L164

It seems that the steps of docker build and docker buildx build are different, so the parseImageId method can not discover the right image name

[andrewhibbert]

Sorry ignore this I've ended up using https://github.com/sbt/sbt-native-packager, see sbt/sbt-native-packager#1527. There is an example in https://github.com/sbt/sbt-native-packager/blob/master/test-project-docker/build.sbt

[nik-kashi]

@marcuslonnberg Do you have any tips for me about what a good approach can be? Then I can try to create a PR for that

[marcus-drake]

@nik-kashi An approach to address this would be to extend the parseImageId function with another regexp that it can use to match and extract the Docker image ID. A PR would be welcomed 🙂