Open Stack

On Fri, 3 Jun 2022 at 14:10, Norrie, Andrew <Andrew.Norrie at cgg.com> wrote:

>
>
> Hi,
>
>
>
> We are currently planning some large OpenStack deployments utilizing
> kolla-ansible and
>
> I’m curious what folks are doing with the cell database HA/redundancy.
>
>
>
> With kolla-ansible (xena) it appears that a loadbalancer setup is only
> allowed for the
>
> default database shard (shard 0)... reference:
> https://docs.openstack.org/kolla-ansible/latest/reference/databases/mariadb-guide.html
>
>
>
> If we are setting up separate cell database shards with Galera, I’m
> wondering if there is a convenient work-around or configuration for
> implementation of HA for these cell databases.
>
>
>
> In the inventory group_vars directory you can specify the group variables
> (for each cell database) as:
>
>
>
> nova_cell_database_address:
>
> nova_cell_database_group:
>
>
>
> but these aren’t virtual IP hosts/addresses (non default db shard). This
> works perfectly fine with
>
> a single server cell database but not Galera. If that db server goes down
> the cell instance information is lost.
>
>
>

Hi Andrew,

You are correct - only the first shard is load balanced. The sharding
feature was actually just the first patch in a series intended to support
proxysql. I believe this would add the functionality you are looking for.
In fact, the proposed test case for proxysql in our CI is a multi-cell
deployment.

Here is the patch series:

https://review.opendev.org/q/topic:proxysql

Unfortunately it has been stuck for a while, largely due to core reviewer
bandwidth. The author is Michael Arbet, who is often on IRC as kevko. I'd
suggest registering your interest in these patches via gerrit, and at one
of the weekly kolla IRC meetings (this week is cancelled due to the
summit). If you have time available, then testing and providing reviews
could help to get the patches moving.

In the meantime, you can configure HAProxy to load balance additional
services, by placing an HAProxy config snippet in
/etc/kolla/config/haproxy/services.d/*.cfg.

Regards,
Mark

Many thanks ... Andrew
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