Virtual-environments: Update/Add CPython 3.9.0 beta 1

[zooba]

Tool information

• Tool name: CPython
• Tool license: Python Software Foundation License
• Add or update? Add
• Desired version: 3.9.0b1 (for CPython, "beta" == "library devs should test with this")
• Approximate size:

Area for Triage:
Python

Question, Bug, or Feature?:
Feature

Virtual environments affected

• [x] macOS 10.15
• [ ] Ubuntu 16.04 LTS
• [x] Ubuntu 18.04 LTS
• [ ] Windows Server 2016 R2
• [x] Windows Server 2019

(Older Ubuntu and Windows is fine too if it's easier, but I don't consider them blocking.)

Can this tool be installed during the build?

Only on Windows via a Nuget package. You can build from source during build for other platforms, which I assume only takes 3-4 minutes (based on our CI running on the same images).

Tool installation time in runtime
Should be under 1 minute

Are you willing to submit a PR?
Sure! Though hopefully this is fairly mechanical, since there's very little difference between how 3.8 is treated and how 3.9 should be treated.

[konradpabjan]

Since this is an in-development version of Python, I would put this under the same issue: https://github.com/actions/setup-python/issues/20

The v2 version of setup-python can now JIT download and install specific versions of Python from the actions/python-versions repo so ideally we should add all in-development versions there.

[maxim-lobanov]

@zooba , as a possible solution, you can build Python 3.9.0 once and cache it using https://github.com/actions/cache. Restoring from cache will take seconds after first build

[zooba]

@maxim-lobanov I work on CPython itself - I don't need the solution. I'm filing it because _everyone else_ needs it, and someone needs to raise the notification that 3.9.0 beta _3_ is now out.

[alepauly]

@konradpabjan @maxim-lobanov I think it makes sense to support latest pre-release via setup-python.

[jadchaar]

Beta 5 is scheduled for release on July 20, so it would be great if this could come soon so we can begin testing our packages on GH actions. Thanks for the hard work!

Ideally it would be cool to just generally support the latest nightly like Alejandro hinted above.

[maxim-lobanov]

Hello @jadchaar ,
We are working on this request right now. We are not planning to pre-cache pre-release versions on image but they will be available for installation on-flight via actions/setup-python with minor latency (15-20 seconds). I think we will finish this request in a week (we have to rework some internal logic to support it).

[The-Compiler]

With https://github.com/actions/setup-python/issues/20#issuecomment-660026867 I suppose this can be closed?

[maxim-lobanov]

Yep, Python 3.9.0 beta 4 is available with latest release of actions/setup-python. Please find details on https://github.com/actions/setup-python/issues/20#issuecomment-660026867

[mattip]

How do I use actions/setup-python on Azure pipelines? Or is there another way to activate 3.9 on the Azure images?

[maxim-lobanov]

@mattip , as far as I know, no way for Azure Pipelines.
actions/setup-python can download versions on-flight and download 3.9.
AzDO UsePython task can't do that. I have logged issue for that some time ago: https://github.com/microsoft/azure-pipelines-tasks/issues/13319
But looks like it is not implemented yet.