Py3.7 RuntimeError: generator raised StopIteration

[Corey Bryant]

Running designate unit tests I hit the following: https://paste.ubuntu.com/p/p4BJWvbCDR/

I believe this is due to changes introduced by https://www.python.org/dev/peps/pep-0479/.

[Dr. Jens Harbott (j-harbott)]

Python 3.7 has introduced incompatibilities for a lot of projects, but I feel it will be difficult to tackle these until we have a stable test environment for it. So this will probably have to wait until the next Ubuntu LTS release that includes 3.7 (or newer?) as default python3 version.

Testing with python3.6 on 18.04 I fail to see the deprecation warnings mentioned in the PEP, so I don't see how we could act on these at the current state.

[Corey Bryant (corey.bryant)]

Jens, I have to disagree with wishlist here. While I understand gate is not running py3.7 tests, these are easy enough to recreate. I'm trying to tackle as many upstream py3.7 fixes as possible but it's a bit overwhelming without some help from others. Filing this under Incomplete/Wishlist will help to get no attention on this.

This can be recreated on Ubuntu Cosmic. Here are some steps that I've used:

1) lxc launch ubuntu-daily:cosmic c1
2) lxc exec c1 /bin/bash
3) root@c1:~# git clone https://github.com/openstack/designate
4) cd designate
5) # update tox.ini to have a py37 target
6) tox -e py37

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/583297

[Corey Bryant (corey.bryant)]

Note that I'm getting hangs when running tests with py3.7 after this fix is applied. (I think the tests fail before reaching the hangs without the fix applied). It may be a separate issue. I'll provide more details shortly.

[Corey Bryant (corey.bryant)]

Pastebin of py3.7 hang/errors mentioned in comment #4:
https://paste.ubuntu.com/p/jY5V6gk9gG/

[Graham Hayes (grahamhayes)]

this looks like a new py3.7 change - https://bugs.python.org/issue33666

[Corey Bryant (corey.bryant)]

I've opened LP:#1782204 for the os.errno Py3.7 failures.

[Corey Bryant (corey.bryant)]

https://bugs.launchpad.net/designate/+bug/1782204

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/583297
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=19b8a6e852da4e2f6b4236e502ed625b7869c271
Submitter: Zuul
Branch: master

commit 19b8a6e852da4e2f6b4236e502ed625b7869c271
Author: Corey Bryant <email address hidden>
Date: Tue Jul 17 09:14:55 2018 -0400

    Replace StopIteration with return for PEP 0479

    PEP 0479, https://www.python.org/dev/peps/pep-0479/, makes the
    following change: "when StopIteration is raised inside a generator,
    it is replaced it with RuntimeError".

    The PEP suggests that if raise StopIteration occurs directly in a
    generator, simply replace it with return.

    Change-Id: I9bb72936c8d56b338084bb0be7e75aecdf09f8b3
    Closes-Bug: #1780827

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/designate 7.0.0.0b3 development milestone.