This is similar to the just-filed bug 1451106, but for Windows. We want Python 3.5+ installed in *all* Windows environments so we can leverage it for builds and tests. The immediate goal is to require Python 3.5 for builds. So that's where priority should be placed. We can scope bloat this bug to cover all machine types or focus just on builders. It doesn't matter much to me. While the requirement in Python 3.5, I would prefer we install Python 3.6 if possible.

AFAIK, this is only an issue for the 32-bit Win7 test machines. All Win64 workers were updated to MozillaBuild 3.1 w/ python 3.6.3 in bug 1413630.

Configure isn't finding Python 3. That's because the "python3" MozillaBuild directory isn't in PATH. I'm not sure who sets PATH. But this is definitely fixable from mozilla-central. Anyway, yes, MozillaBuild's Python 3.6 install qualifies. So all Windows builders should be good.

This is also the case for w10.

The OpenCloudConfig files are setting the path, e.g. https://github.com/mozilla-releng/OpenCloudConfig/blob/b2b0cf37b99828e6b8261a0392d825f642d65be4/userdata/Manifest/gecko-t-win7-32.json#L421 and https://github.com/mozilla-releng/OpenCloudConfig/blob/master/userdata/Manifest/gecko-t-win10-64.json#L349.

What are we going to do on test machines that are still using 32 bit Windows?

(In reply to Marco Castelluccio [:marco] from comment #5) > What are we going to do on test machines that are still using 32 bit Windows? now testing install of python 3.6.3 on windows 7 beta workers: https://github.com/mozilla-releng/OpenCloudConfig/commit/81ce6f4e9df0071f3defc2f497acc66dea738773

Nice, thanks! I guess we can't simply add Pyhthon 3 to the PATH as otherwise the two Python installations would conflict.

(In reply to Marco Castelluccio [:marco] from comment #7) > I guess we can't simply add Pyhthon 3 to the PATH as otherwise the two > Python installations would conflict. indeed. it would be confusing to anyone not familiar with the path order to know which version of python is running. for now, it's probably best to rely on using the full path to python 3 (c:\mozilla-build\python3\python.exe), when that's what's wanted.

install to beta was successful: https://tools.taskcluster.net/groups/ZUSBLZWrRt-KdU5ihmshDA/tasks/ZUSBLZWrRt-KdU5ihmshDA/runs/0/logs/public%2Flogs%2Flive.log

we're now adding c:\mozilla-build\python3 to the system PATH environment variable after removing c:\mozilla-build\python3\python.exe to avoid confusion over which python version is executing (see bug 1505057). when that work is complete, - calling `python.exe`, `python2.exe` or `python2.7.exe` without specifying a path, will give you python 2.7.11 - calling `python3.exe` without specifying a path, will give you python 3.6.3 this will be true for all taskcluster windows worker types: - gecko-1-b-win2012 - gecko-1-b-win2012-beta - gecko-2-b-win2012 - gecko-3-b-win2012 - gecko-t-win7-32 - gecko-t-win7-32-beta - gecko-t-win7-32-gpu - gecko-t-win7-32-gpu-gpu-b - gecko-t-win10-64 - gecko-t-win10-64-beta - gecko-t-win10-64-gpu - gecko-t-win10-64-gpu-gpu-b