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I'm looking to set up a writing proxy for our MariaDB database on Kubernetes. The problem we are currently having is that we only have one Write master on our 3 master galera cluster setup. So even though we have ours pods replication properly, if our first node goes down then our other two masters end up failing because they are not able to be written to.

I saw this was a possible option to use either ProxySQL or MaxScale for Write proxying, but I'm not sure if I'm reading their uses properly. Do I have the right idea looking to deploy either of these two applications/services on Kubernetes to fix my problem? Would I be able to write to any of the Masters in the cluster?

Eric Fritz
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1 Answers1

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MaxScale will handle selecting which server to write to as long as you use the readwritesplit router and the galeramon monitor.

Here's an example configuration for MaxScale that does load balancing of reads but sends writes to one node:

[maxscale]
threads=auto

[node1]
type=server
address=node1-address
port=3306

[node2]
type=server
address=node2-address
port=3306

[node3]
type=server
address=node3-address
port=3306

[Galera-Cluster]
type=monitor
module=galeramon
servers=node1,node2,node3
user=my-user
password=my-password

[RW-Split-Router]
type=service
router=readwritesplit
cluster=Galera-Cluster
user=my-user
password=my-password

[RW-Split-Listener]
type=listener
service=RW-Split-Router
protocol=mariadbclient
port=4006

The reason writes are only done on one node at a time is because doing it on multiple Galera nodes won't improve write performance and it results in conflicts when transactions are committed (applications seem to rarely handle these).

markusjm
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  • Thank you for the insight, we ended up not doing multiple writes at a time was because of this very reason. We are utilizing ProxySQL instead of MaxScale. – Eric Fritz Aug 29 '22 at 18:55