Monitoring a database in standalone mode is one thing, but clustering makes it a lot more complex.
That’s exactly the case with Galera clustering (MariaDB/MySQL). Zabbix and similar tools gave me simple solutions for single database servers, but I couldn’t find a template I actually liked for monitoring a Galera cluster in production.
So a few questions came up: what to monitor, how to alert, and what the best approach would be.
I used the official Galera documentation as my reference for all the important elements to keep an eye on. I picked Go because it gave me the functionality I needed, and for alerting I went with a Slack app.
Example of a healthy output:
> go run main.go
### Version ####
2017/06/16 14:19:48 Serveur n1 - version 5.6.35-1xenial
2017/06/16 14:19:48 Serveur n2 - version 5.6.35-1xenial
2017/06/16 14:19:48 Serveur n3 - version 5.6.35-1xenial
### UUID ###
2017/06/16 14:19:48 n1 a1c404a9-51b4-11e7-b057-237cc5970d38
2017/06/16 14:19:48 n2 a1c404a9-51b4-11e7-b057-237cc5970d38
2017/06/16 14:19:48 n3 a1c404a9-51b4-11e7-b057-237cc5970d38
### Nodes ###
2017/06/16 14:19:48 Total Nodes : 3
2017/06/16 14:19:48 Number of Nodes counts : 3
2017/06/16 14:19:48 Number of Nodes counts : 3
2017/06/16 14:19:48 Number of Nodes counts : 3
### STATUS ###
2017/06/16 14:19:48 n1 status : Primary
2017/06/16 14:19:48 n2 status : Primary
2017/06/16 14:19:48 n3 status : Primary
2017/06/16 14:19:48 n1 is ready : [ON]
2017/06/16 14:19:48 n2 is ready : [ON]
2017/06/16 14:19:48 n3 is ready : [ON]
2017/06/16 14:19:48 n1 is connected : [ON]
2017/06/16 14:19:48 n2 is connected : [ON]
2017/06/16 14:19:48 n3 is connected : [ON]
### Average Replication ###
2017/06/16 14:19:48 Average on n2 : 0.000000
2017/06/16 14:19:48 Average on n3 : 0.000000
2017/06/16 14:19:48 Average on n1 : 0.100000
You need to use the slackApp package, where I’ve exposed a PayloadSlack() function so you can customize your alerts.
The full output isn’t printed to STDOUT when everything is healthy. If you want to run your own tests, just uncomment the println calls in main.go.