Support pr channels

[LilithHafner]

It would be lovely to have julia +pr54152 download and run the binaries built from the pull request # 54152 (if binaries are available). If the build failed or the PR is old enough that the binaries have been discarded or my system is not compatible with any of the CI systems then I wouldn't expect this to be possible, but in most cases I care about none of those are the case. It would make interactive testing of a PR much nicer to e.g. verify that purported performance improvements are real.

I recall hearing on slack that with the new nightly support this shouldn't be too hard, but I can't find that conversation now.

[davidanthoff]

All we need is a stable URL scheme where these can be downloaded, which is something that needs to happen on the Julia CI side of things. Once we have something like https://julialangnightlies-s3.julialang.org/bin/macos/x86_64/pr/pr12345/julia-pr12345-latest-macos-x86_64.tar.gz it would be almost trivial to add support for this to Juliaup.

[StefanKarpinski]

@staticfloat Is this possible?

[staticfloat]

JuliaCI/julia-buildkite#362

[vchuravy]

What happens on a push/force-push? I assume the binary on AWS gets replaced, but Julia up probably needs to be able to quickly check it the local binary is now out of date.

[davidanthoff]

As long as the etag header on the URL for the PR changes when a new build is pushed, it should all work and Juliaup should be able to detect new versions. Its the same mechanism used for the nightly channel.

[staticfloat]

Do you need .exe or .dmg files for Windows or macOS? Or is it sufficient for me to just upload tarballs everywhere?

[davidanthoff]

We only ever download the tarballs, no need for anything else.

[staticfloat]

Okay, here's some example PR URLs:

• https://julialangnightlies-s3.julialang.org/bin/windows/x86_64/julia-pr54876-windows-x86_64.tar.gz
• https://julialangnightlies-s3.julialang.org/bin/macos/aarch64/julia-pr54876-macos-aarch64.tar.gz
• https://julialangnightlies-s3.julialang.org/bin/macos/x86_64/julia-pr54876-macos-x86_64.tar.gz
• https://julialangnightlies-s3.julialang.org/bin/linux/x86_64/julia-pr54876-linux-x86_64.tar.gz
• https://julialangnightlies-s3.julialang.org/bin/linux/aarch64/julia-pr54876-linux-aarch64.tar.gz