RISC-V support

[MarekPikula]

Hi, I use Docker-in-Docker image to build Docker images in GitLab CI. With the soon introduction of RISC-V native runners (with Cloud-V: https://cloud-v.co/gitlab-riscv-runner) I would like to build the RISC-V images on the native hardware but there seems to be no official variant for linux/riscv64 platform in the latest tag.

What would need to happen to introduce an official RISC-V support for DinD image? Alpine already has official base image builds, so it should be no problem to enable the platform in the build matrix, right?

[tianon]

We get our builds of Docker from https://download.docker.com/linux/static/stable/, which unfortunately doesn't currently include riscv64.

[MarekPikula]

Thank you for pointing me there. Are you aware of any efforts in bringing official RISC-V support upstream?

[AaronDewes]

If you're interested in an alternative, I've built unofficial images at harbor.nirvati.org/library/docker:28-cli and harbor.nirvati.org/library/docker:28-dind.

https://gitlab.com/nirvati/risc-v/utils/docker-risc-v-builds
https://gitlab.com/nirvati/risc-v/utils/docker

It's a slightly patched of dockerd and docker-cli, so it's not official.

[MarekPikula]

Thanks for the pointer @AaronDewes. Are you planning to upstream your work any time soon? To be honest, I would prefer to stick to the official images.

[AaronDewes]

I can't really upstream most of it because I'm mostly just recompiling dockerd. I have two patches for rootlesskit, I can have a look at the possibility of upstreaming these, but the main issue is Docker not having official builds.

In essence, I forked the older version of mirage-entropy vpnkit uses and added this patch: https://gitlab.com/nirvati/risc-v/mirage-entropy/-/commit/78f90076fa2d73efa47b06290e39656915b07090

But because it's an outdated/unmaintained version, I can't submit it directly as-is.

[tianon]

I think moby/moby#44319 (comment) and/or docker/docker-ce-packaging#1072 are the closest things I can find to an "upstream" tracker for riscv64 builds on download.docker.com.

[tianon]

(closing in favor of upstream trackers)