o/
A whole 2 years and 8 months to the day after I first communicated about it [1], it would appear the requirements bump to SQLAlchemy 2.0 [2] is finally ready to go. I suspect most if not all service projects are familiar with SQLAlchemy 2.0 at this point, having needed to fix whatever compatibility issues were seen. For those that aren't, I suggest reading my previous emails on the matter.
So what happens next? Hopefully for the vast majority of projects the answer should be "nothing": many projects now have sqlalchemy-tips jobs that are designed to run unit and/or integration tests with the latest versions of SQLAlchemy, Alembic and oslo.db so the switchover should be seamless. I foresee three situations:
* For projects that continue working as-is post-bump, you may wish to delete the sqlalchemy-tips jobs now. The jobs were designed as a stop gap measure to prevent projects regressing on SQLAlchemy 2.0 support while we got other projects over the line. While there is some limited value in keeping these jobs around, they do consume resources and - to the best of my knowledge - the SQLAlchemy community is not planning to release a 3.0 version of SQLAlchemy (or 2.0 version of Alembic) any time soon :) The requirements jobs gates on many projects and should identify compatibility issues with these libraries going forward, so it's probably best to drop them from the projects. I'll push a couple of patches shortly to do just this. Feel free to accept or reject them as you see fit.
* For projects that are supposed to be SQLAlchemy 2.0 Ready (TM) but start seeing issues that the sqlalchemy-tips jobs didn't catch (because, say, the job was running unit tests rather than functional tests and the unit tests are missing coverage), I'd encourage you to look through what is now a fairly extensive repository of patches [3] that we've built up while addressing SQLAlchemy 2.0 compatibility issues. These are mostly all tagged with the sqlalchemy-20 topic and there's a very good chance that a patch addressing your specific issue has already been submitted to another project.
* For projects that were not in the gating queue for requirements bumps, have not prepped for SQLAlchemy, and start failing catastrophically post-bump: have you not been listening to me?! :) You've got some work to do but fortunately that work should be relatively simple (if a bit tedious). As noted above, there are a *lot* of patches that you can look through to identify solutions to your compatibility issues. My preferred strategy - which is the one also advocated for by the SQLAlchemy 2.x docs [4] - has been to configure the warnings filter to raise an error for all SQLAlchemy deprecation warnings then filter out those that we actually hit and iteratively work to remove these filters. That won't work now that SQLAlchemy 2.0 is in upper-constraints so you're going to have to fix it all in one go. You may wish to adopt the standard approach locally though, before squashing all the commits upon review.
This has already consumed far (far!) too much of my time so I won't offer to undertake the migration of any outstanding projects. I am, however, happy to field questions and point to existing patches that resolve a given issue. Hopefully none of it will be necessary though.
Cheers, Stephen
[1] https://lists.openstack.org/pipermail/openstack-discuss/2021-August/024122.h... [2] https://review.opendev.org/c/openstack/requirements/+/879743 [3] https://review.opendev.org/q/topic:sqlalchemy-20 [4] https://docs.sqlalchemy.org/en/20/changelog/migration_20.html