[keystone][cache] How to tune role cache

Eugen Block eblock at nde.ag
Wed Oct 26 07:44:17 UTC 2022


Hi *,

one of our customers has two almost identical clouds (Victoria), the  
only difference is that one of them has three control nodes (HA via  
pacemaker) and the other one only one control node. They use terraform  
to deploy lots of different k8s clusters and other stuff. In the HA  
cloud they noticed keystone errors when they purged a project  
(cleanly) and started the redeployment immediately after that. We did  
some tests to find out which exact keystone cache it is and it seems  
to be the role cache (default 600 seconds) which leads to an error in  
terraform, it reports that the project was not found and refers to the  
previous ID of the project.
The same deployment seems to work in the single-control environment  
without these errors, it just works although the cache is enabled as  
well.
I already tried to reduce the cache_time to 30 seconds but that  
doesn't help (although it takes more than 30 seconds until terraform  
is ready after the prechecks). But the downside of disabling the role  
cache entirely leads to significantly longer response times when using  
the dashboard or querying the APIs.
Is there any way to tune the role cache in a way so we could have both  
a reasonable performance as well as being able to redeploy projects  
without a "sleep 600"?
Any comments or recommendations are appreciated!

Regards,
Eugen




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