A quick summary...
This week, a new protobuf release dropped Python 2.7 and 3.5 support, causing tox-py27 builds for zuul-jobs changes to fail, raising SyntaxError importing roles.upload-logs-base.library.test_zuul_google_storage_upload. The proposed fix is to use an environment marker to pin to earlier protobuf on Python<3.6 for now:
https://review.opendev.org/809460
Another slightly more tricky problem is that this week, a new Virtualenv release bundled a new major version of SetupTools which dropped support for its old use_2to3 option. This has caused problems for a number of very old Python packages, but in our case specifically funcparserlib which was last fully released in 2013. Using latest virtualenv, attempts to install funcparserlib or anything which requires it will just break. We have one document in zuul-jobs (docker-image.rst) which uses blockdiag and seqdiag directives, and that is indirectly responsible for pulling in the funcparserlib package. Thankfully, the funcparserlib maintainers acted quickly and proposed an alpha release which we can explicitly require until the blockdiag project merges a pending pull request to do so itself, and this is proposed already:
https://review.opendev.org/809885
Unfortunately, that new alpha release also drops Python 3.5 support, meaning we can't build the zuul-jobs docs (well, docker-image.rst specifically) on Ubuntu Xenial. That might seem like a small thing, we build and publish the zuul-job docs with much newer Python anyway, however the way we've chosen to test the fetch-sphinx-tarball role is to run `tox -e docs` for zuul-jobs on lots of different platforms, one of which is Ubuntu Xenial. Dropping support for Python 3.5 is happening in new releases of projects right and left, and as of January 2022 pip itself intends to make a new release which will no longer work on Python 3.5, so if we intend to continue testing things on Ubuntu Xenial at all, we're almost certainly going to need to work out how to do so with older toolchains which can still work on its Python version.
So here's the dilemma, and my question to you. Do we:
A. rework the fetch-sphinx-tarball role test to no longer use the docs/requirements.txt in zuul-jobs?
B. redo docker-image.rst to switch from blockdiag and seqdiag to something else (another Sphinx plugin, pre-rendered images...)?
C. adjust tools/update-test-platforms.py to allow us to exclude specific autogenerated jobs we know can never work and use that to drop the zuul-jobs-test-fetch-sphinx-tarball-ubuntu-xenial?
D. remove Ubuntu Xenial testing for zuul-jobs in general?
E. some other solution I'm too braindead to come up with on a hot Friday afternoon?
Feedback on where I should go from here would be much appreciated!