Modules with known eventlet monkey patching issues were imported prior to eventlet monkey patching: urllib3

[Balazs Gibizer]

Since we reenabled greendns with[1] nova functional test prints a warning at startup:

2022-07-08 11:03:40.374564 | ubuntu-focal | Modules with known eventlet monkey patching issues were imported prior to eventlet monkey patching: urllib3. This warning can usually be ignored if the caller is only importing and not executing nova code.

This is coming from [2]. It seems we think that urllib3 has monkey patching issues as reported in [3].

Based on tracing the imports eventlet import urllib3 for the greendns feature.

So I'm wondering if by reenabling greendns with [1] we actually reintroduced [3]. If yes, then we probably need to revert [1]. If not, then we probably remove urllib from our problems list in [2].

Example logs are in [4].

[1]https://review.opendev.org/c/openstack/nova/+/830966
[2]https://github.com/openstack/nova/blob/90c0c687a487601e009c72f60c88be92f6a55264/nova/monkey_patch.py#L76
[3]https://bugs.launchpad.net/nova/+bug/1808951
[4]https://zuul.opendev.org/t/openstack/build/5ff0d13fd8db4719bb0407b42c510e09/log/job-output.txt#1706-1714

[Balazs Gibizer (balazs-gibizer)]

After discussing this with Sean over IRC[5]. We concluded that:
a) either urllib3 needs to be removed from the problems list[2] if eventlet fixed the urllib3 patching issue[3]
b) or we need to file a bug on eventlet to do so.

personally I would be feel safer if we would revert[1]. But we have no consensus there right now.

[5] https://meetings.opendev.org/irclogs/%23openstack-nova/%23openstack-nova.2022-07-08.log.html#t2022-07-08T12:51:02

[sean mooney (sean-k-mooney)]

i dont feel comfortable reverting https://review.opendev.org/c/openstack/nova/+/830966 since we know it will break people and you can simple disable greendns by setting the environment varble

previously nova hardcoded os.environ['EVENTLET_NO_GREENDNS'] = 'yes'

if people encounter issue with wsgi the can simply export EVENTLET_NO_GREENDNS='yes'
in the environment

if we revert that change we reintorduce https://bugs.launchpad.net/nova/+bug/1964149

which caused multiple downstream customer escalations and outaages.