keystone's keystone.conf.memcache socket_timeout isn't actually used

[Lance Bragstad]

Keystone has a timeout configuration option for memcache [0]. Keystone's definition of this option isn't actually used anywhere, so it appears to be a broken knob.

In fact oslo.cache has a duplicate option that appears to be used instead [1].

We should deprecate the keystone-specific option and point people to the oslo.cache option.

[0] https://opendev.org/openstack/keystone/src/commit/a0aa21c237f7b42077fc945f157844deb77be5ef/keystone/conf/memcache.py#L26-L32
[1] https://opendev.org/openstack/oslo.cache/src/commit/a5023ba2754dd537c802d4a59290ff6378bd6285/oslo_cache/_opts.py#L85-L89

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/672629

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/672629
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=4b747fa083ad09ae8ba92dadc63ac0b830c7e562
Submitter: Zuul
Branch: master

commit 4b747fa083ad09ae8ba92dadc63ac0b830c7e562
Author: chenxing <email address hidden>
Date: Thu Jul 25 13:53:21 2019 +0800

    Deprecate keystone.conf.memcache socket_timeout

    Change-Id: I5de14b5bd2d96c2f78152eda48842d388109e02b
    Partial-Bug: #1838037
    Closes-Bug: #1837407

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/keystone 16.0.0.0rc1 release candidate.

[Takashi Kajinami (kajinamit)]

I'm afraid this was very incomplete work since the other parameters in [memcache] section are also unused. I have created a separate bug to deprecate all unused parameters.[1]

 https://bugs.launchpad.net/keystone/+bug/1941020