Open Stack

On 08/12/15 04:04, Matt Fischer wrote:
> On Mon, Dec 7, 2015 at 3:54 AM, Ajaya Agrawal <ajku.agr at gmail.com> wrote:
> 
>> Hi everyone,
>>
>> We are deploying Openstack and planning to run multi-master Galera setup
>> in production. My team is responsible for running a highly available
>> Keystone. I have two questions when it comes to Galera with Keystone.
>>
>> 1. How do you test if a Galera cluster is setup properly?
>> 2. Is there any Galera test specific to Keystone which you have found
>> useful?
>>
>>
> For 1 you could say that the clustercheck script which ships with
> puppet-galera and is forked from
> https://github.com/olafz/percona-clustercheck is a really simple check that
> galera is up and the cluster is sync'd. It's main goal however is to
> provide status to haproxy.
> 
> One thing you want to check is the turnaround time on operations, for
> example, creating a user on a node and then immediately using them on
> another node. We found that this is likely to sometimes (but rarely) fail.
> The solution is two-fold, first, don't store tokens in mysql. Second,
> designate one node as the primary in haproxy.
> 

+1 for designating one node as primary.  This helped us reduce some
deadlocks that we were seeing when balancing sessions between DB hosts.

> Other than that we've gotten good at reading the wsrep_ cluster status
> info, but to be honest, once we removed tokens from the db, we've been in
> way better shape.