Make Dockerfile compatible with ARM architecture

[KEINOS]

[Enhancement]

Happy New Year!

Currently (as of 3641b3f), the Dockerfile creates an image for AMD64 (Intel-compatible) binary with GOARCH=amd64 option.

kagome/Dockerfile

Lines 21 to 32 in 3641b3f

	RUN apk --no-cache add git && \
	version_app=$(git describe --tag) && \
	echo "- Current git tag: ${version_app}" && \
	go version && \
	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
	-a \
	-installsuffix cgo \
	--ldflags "-w -s -extldflags \"-static\" -X 'main.version=${version_app}'" \
	-o /go/bin/kagome \
	./cmd/kagome && \
	echo '- Running tests ...' && \
	/go/bin/kagome version

It would be nice to provide Dockerfile for ARM architecture as well. Such as RaspberryPi 3 (ARMv7) and Raspberry Pi Zero (ARMv6).

Seems that Golang supports ARM architecture and has some success stories on Raspberry Pies.

If I may, as soon as I success to make one, I will PR the Dockerfile. But please keep your expectations low. ;-)

[ikawaha]

Sounds good!

[KEINOS]

Finally, I think I came up with a solution to fix this issue.

With this fix, we can provide "ikawaha/kagome:latest" Docker image tag which is compatible with x86_64 (Intel/AMD) and ARMs. Such as ARM v6 (RasPi Zero) and ARM v7 (RasPi 3+). (Maybe compatible with the upcoming ARM Mac as well)

But before any PR, I have a question.

Do you prefer to use GitHub Actions to automate the build and push the images to DockerHub?
or wish to release the images manually?

1. Automatic
   • PROS: Once the settings are set, only push your commit to "v2" branch and will automatically release the docker images.
   • CONS: You need to set the TOKENs from Docker Hub to the GitHub repo's secret setting for the first time.
2. Manual
   • PROS: You can control the tags.
   • CONS: You need to enable the experimental feature of Docker.

I suggest the first one, automate, using the GitHub actions.

The thing is that, to make a single Docker image tag,"ikawaha/kagome:latest", which works on all those platforms above is a little complicated.

Because there's a long-lasting bug in Docker which can not detect the architecture, if "arm/v6" and "arm/v7" are mixed in one tag (manifest).

• "ARMv6 machine pulls v7 image from manifest list" moby/moby#37647

To make it work, we need a temporary workaround. (Change the variant value of "arm6" and "arm7" in "latest" tag's manifest)

I made a GitHub action to do all the things for this. But if you prefer to release the images manually, I will create a shell script to do so.

• Sample GitHub Actions workflow in my fork @ GitHub
• Sample Docker image: keinos/kagome:latest @ DockerHub

[ikawaha]

I prefer automated releases! ╭( ･ㅂ･)و ̑̑

[KEINOS]

roger (￣^￣)ゞ

I will PR what I came up with, as soon as I finish some refactoring (cleaning) the workflow.

[ikawaha]

╭( ･ㅂ･)و ̑̑ Thank you for your great contributions!
We are now able to provide Docker containers for AMD/ARM environments. 🎉

[KEINOS]

We did it. 10 months to close the issue... finally 😄