MySQL: Use CheckMk to monitor MySQL

CheckMk is a great tool for monitoring. Especially when it comes to standard functions for operating systems.

But CheckMk is also great for the monitoring of MySQL databases.

If you want to use it, just install the CheckMk agent on the MySQL server. Additionally, you'll need the MySQL plugin:

Setup -> Linux -> Plugins -> mk_mysql

Copy it to

/usr/lib/check_mk_agent/plugins

and change execution rights:

# chmod +x mk_mysql

Additionally, you'll need something to make the plugin able to login to the database(s), like a configuration file:

/etc/check_mk/mysql.cfg

Only user and password are used. To simplify, I used plaintext, but you could also use other configurations:

[client]
user=root
password=XxXxXxXx

If your environment is more complex, you should look at the CheckMk documentation.

You can test the Plugin like that (using the root user):

# cd /usr/lib/check_mk_agent/plugins
# MK_CONFDIR=/etc/check_mk ./mk_mysql 

The output should look like this:

<<<mysql_ping>>>
[[]]
mysqld is alive
<<<mysql>>>
[[]]
Aborted_clients	0
Aborted_connects	0
Acl_cache_items_count	0
Binlog_cache_disk_use	0
Binlog_cache_use	0
Binlog_stmt_cache_disk_use	0
Binlog_stmt_cache_use	0
Bytes_received	190381
Bytes_sent	5237168
[...]
tls_version	TLSv1.2,TLSv1.3
tmp_table_size	16777216
tmpdir	/tmp
transaction_alloc_block_size	8192
transaction_isolation	REPEATABLE-READ
transaction_prealloc_size	4096
transaction_read_only	OFF
unique_checks	ON
updatable_views_with_limit	YES
version	9.2.0
version_comment	MySQL Community Server - GPL
version_compile_machine	x86_64
version_compile_os	Linux
version_compile_zlib	1.2.13
wait_timeout	28800
windowing_use_high_precision	ON
xa_detach_on_prepare	ON
<<<mysql_capacity>>>
[[]]
information_schema	0	0
mysql	2736128	339738624
performance_schema	0	0
sys	16384	0
<<<mysql_replica_slave>>>
[[]]

To be able to monitor the MySQL plugin results, we have to run the service discovery (the yellow box):

We can now finde new services:

We can acknowledge them, an then, MySQL is under monitoring.

To make sure that all the changes are persisted, we have to acknowledge the changes:

After a while, the plugin has collected some data, and you can see it in monitoring: