a single memcache host should be used for keystone cache

[Boris Bobrov]

Now fuel sets option [cache]memcache_servers in keystone.conf to a list of memcache hosts, each host being a controller. For example, if controllers have ips 192.168.0.6, 192.168.0.7 and 192.168.0.8, then [cache]memcache_servers=192.168.0.6,192.168.0.7,192.168.0.8 on all controllers. This creates an unnecessary point of care about HA. If a node goes down, we need to wait at least socket_timeout seconds for each cache check.

[cache]memcache_servers should be set to a single local memcache instance: [cache]memcache_servers=192.168.0.6 for controller with ip 192.168.0.6 etc.

Pros:
 - faster cache -- no need to connect somewhere via network
 - no need to care about HA in cache

Cons:
 - cache is no longer shared

[Boris Bobrov (bbobrov)]

I would also like to have this backported to 6.1

[Oleksiy Molchanov (omolchanov)]

Need to have scale test results in order to compare and make a decision.

[Bogdan Dobrelya (bogdando)]

The 7.0 will use fernet tokens from the Kilo. Hence, invalid for the 7.0

[Boris Bobrov (bbobrov)]

No, it is valid for 7.0. This is about cache, not about tokens.

[Boris Bobrov (bbobrov)]

for some reason scale tests fail with message that user X has no access to tenant Y. I am investigating it now.

[Denis Egorenko (degorenko)]

https://review.openstack.org/210305

[Bogdan Dobrelya (bogdando)]

As Sergii Golovatiuk have noticed, this is not a bug, this a change request to A-A keystone architecture.

[Vitaly Sedelnik (vsedelnik)]

Won't Fix for 6.1-updates because of Wishlist importance

[Bogdan Dobrelya (bogdando)]

According to review comments:
> this change only affects keystone local data cached?
yep
> Or does it affect the cached auth tokens as well
we don't cache tokens. But tokens issued and stored are not affected

this change doesn't affect HA UX and may be accepted for the 7.0 as an ordinary bugfix. Hence, returned priority back from the wishlist

[Boris Bobrov (bbobrov)]

I'm going to mark this bug as "won't fix" for 7.0 due to the issues we faced (bug 1494435)

[Boris Bobrov (bbobrov)]

Marking as won't fix for 8.0 too for the same reason.