CONF.set_override doesn't alias deprecated opts

[Eric Fried]

If I deprecate opt 'bad' in favor of opt 'good', I can still use a conf file that sets 'bad', and CONF.good will show up in my code with that value.

However, when I CONF.set_override('bad', ...), the override value shows up in CONF.bad, but not in CONF.good.

Example:

=============================
from oslo_config import cfg
from oslo_log import log

log.logging.basicConfig(level='DEBUG')

goodopt = cfg.StrOpt('good')
badopt = cfg.StrOpt('bad')
goodopt.deprecated_opts = [cfg.DeprecatedOpt('bad')]

cfg.CONF.register_opts([goodopt, badopt])

cfg.CONF()
print('good: %s' % cfg.CONF.good)
print('bad: %s' % cfg.CONF.bad)
cfg.CONF.set_override('bad', 'bar')
print('good: %s' % cfg.CONF.good)
print('bad: %s' % cfg.CONF.bad)
=============================

With conf file:

=============================
[DEFAULT]
bad = foo
=============================

Actual output:
=============================
WARNING:oslo_config.cfg:Option "bad" from group "DEFAULT" is deprecated. Use option "good" from group "DEFAULT".
good: foo
bad: foo
good: foo
bad: bar
=============================

Expected output:
=============================
WARNING:oslo_config.cfg:Option "bad" from group "DEFAULT" is deprecated. Use option "good" from group "DEFAULT".
good: foo
bad: foo
good: bar
bad: bar
=============================

[ChangBo Guo(gcb) (glongwave)]

Usually set_override is used in tests. I suggest use CONF.good in code, just leave CONF.bad for operators.

[Eric Fried (efried)]

@gcb - Yes, sorry I didn't mention that this only affects test. I hit it when trying to write this one: https://review.openstack.org/#/c/492247/6/nova/tests/unit/cmd/test_status.py@148

Thanks!

[Doug Hellmann (doug-hellmann)]

When bad is deprecated, it should no longer be registered at all.

And gcb is right, the test code should be updated when an application deprecates an option.

[Eric Fried (efried)]

I won't fight this, but I'd like to clarify/restate the effect of the bug:

I can't write unit test code confirming that the deprecated opt still works.