hi folks,
TL;DR ----- this is a long email so the tl;dr is we should add pyproject.toml ``` [build-system] requires = ["pbr>=5.7.0", "setuptools>=36.6.0", "wheel"] build-backend = "pbr.build" ``` to all openstack projects to supprot pip 23.1+
Long version ------------ As some of you may know the ptg happend last week an done of hte topic raised there was a know limitation in devstack where GLOBAL_VENV=True does not work on centos/fedora derived distros.
while i generally dont use centos/fedora derived distros for my daily work i have been using devstack for over 10 years at this point so when im told it broken i ocationlly will go fix it. In this case the issue is not with devstack (it often isnt) and is actully in our collective reliance on a deprecated functionality and how we package openstack today.
Back story, for better or worse when openstack was created the landscape of python packaging was significantly different then it is today. To help corodinate our dependcies the openstack comunity went all in on requirements.txt and developed upper-constraits to manage our requirements and developed PBR (python build Reasonableness). both of those approches have served us well and likely will continue to do so for some time. Since then pyproject.toml has started to gain popularity and pep-517 (A build-system independent format for source trees) has been adotpted but so far openstack as a comunity has not embraced those changes. (although pbr already supprot pep-517 :) ). Until now this has not been a problem however with recent release of pip things are now breaking.
Problem Context: - openstack does not provide pyporject.toml files - openstack project configure setuptools to use pbr via setup.py - setuptools support generating scripts form entry points(console_scripts) which we use for project binaries( nova- compute, neutron-server, ...) - openstack api services use a pbr extension know as wsgi_scripts which adds a similar functionality for generating wsgi application mains file - devstack due to coming changes in distro to block "sudo pip install" now installs openstack in a single by default on debian distros. on centos/fedora distros it currently almost functional (but not). - devstack installs in editable mode because that is how most developers use devstack for developemnt
What changed: - pip 20.2 deprecated support for falling back to calling setup.py when pyproject.toml is not present - https://pip.pypa.io/en/stable/news/#v20-2 - https://github.com/pypa/pip/issues/8368 - at this point when pyproject.yaml is not called pip calls setup.py install [-e] <path to repo or package name> - setup.py invokes pbr to generate wsgi_scripts and other files - in pip 23.1 the fallback was removed https://pip.pypa.io/en/stable/news/#v23-1 - pip now builds a temp local wheel instead of calling setup.py install when pyproject.toml is not found - in editable mode (-e) the default way the wheel is built does not invoke pbr properly to generate the wsgi files - as a result the wsgi files are not installed to the venv bin dir and this causes devstack to fail to start keystone (or any other wsgi api)
The fix, there are a few ways to approch this: - clamp pip (https://review.opendev.org/c/openstack/devstack/+/898845) this is a terible idea and it breaks debian - clamping pip below 23.1 works on centos for now however OVS on debian already requires pep 517 for installing - as such when that version of ovs (or other projects start enforcing that) hits centos it will break - add a minimal pyproject.toml to all openstack project - example for keystone https://review.opendev.org/c/openstack/keystone/+/899519 - this example jsut adds the minium pyproject.toml to enable pbr to be used as the build system - it does not remove supprot for setup.py but it will not be used by default going forward whit new version of pip - all config is still in setup.cfg - add pyproject.toml support but remove setup.py support https://review.opendev.org/c/opendev/bindep/+/816741 - this goes one step futrue and actuly nulls out setup.py - we could take this approach if we want to but its not required.
The reason for this email is to get agreement on how to support pip 23.1+ My proposal would be to add pyproject.toml with the minimal config required to enable pip 23.2 but not drop the setup.py support in this cycle. i would suggest that we can deprecate installing via setup.py in caracal if that is desirable but not make that change until the next slurp to give time to projects and packages to catch up.
if there are no objections to that i would like to ask what is the preferd way to create and submit the patches for the minimal pyproject.toml
``` [build-system] requires = ["pbr>=5.7.0", "setuptools>=36.6.0", "wheel"] build-backend = "pbr.build" ```
i can propose patches to the main project deployed by devstack by default. i.e. nova/neutron ectra but it might be better if someone form the core teams of each project could take on that task and chasing the reviews. if someone has a script to generate a patch for a set of repos that just add the above pyporject.toml then we can use that to keep a consistent topic/commit message across all patches.
my proposal for testing this is two fold. in ci we can test the patches are functional by using a DNM patch to devstack to force enable the gloal venv on centos and depend on the set of patches, i will modify https://review.opendev.org/c/openstack/devstack/+/898845 to do that
locally we can test that the patch is functional by doing the following substituting keystone for the relevant project. ``` git clone https://opendev.org/openstack/keystone cd keystone python3 -m venv .venv . .venv/bin/activate python3 -m pip install -U pip python3 -m pip install -e . ls .venv/bin/keystone* ```
the ls will not contain the wsgi script with the addition of the pyproject.toml it should.
on debian sid i can reproduce the same issue the problem we are seeing on centos 9 now will start impacting other distos eventually so its good to fix this now.
if i start proposing this to glance/nova/neutron/cinder/swift/horizon/placement (to get a default devstack working) can i get cores to review? can cores form each project nominate peopel to review or volenteer to do this work. i have created https://etherpad.opendev.org/p/pep-517-and-pip-23 to track this work
i have some other work that i think we can do in parallel like addign pyporject.toml support to the pti requirements if we go this way but that i think we can discuss on a governacne patch to updated it.
anyway this is a lot to digest so feedback is welcome. if someone else would like to drive this that is also welcome (i.e. tc/release team)
regards sean.