Add a New User Defined Check in Zabbix

It is very easy to add a new check in Zabbix.

Even though there are hundreds of templates available for monitoring using zabbix, we may still need to monitor something special in our environment. You may be able to write a script for this purpose, but you will need to add that to the standardized monitoring tool you have in your organization. There are multiple ways to add a new check in zabbix monitoring, I found it very easy using UserParameter.

I will show you How did I configured a new check in zabbix for monitoring multi source  replication in maria DB.


My Requirement:
I have four slaves running in a Maria DB instance. I want to monitor if any of the threads are not running, and I should get a pager if any thread is down.

The output of the below command should be 0 at any point. More than zero means there is a failure

mysql -umysql_backup -pxxxx -e"show all slaves status \G"| grep "Running: No"| wc -l

You can create a command like this for anything you want to monitor, and it should be returning a number or character.

Implementation:

Go to the server to be monitored, My case it is mysqlslave.myfirm.com

Edit the zabbix configuration file. ( location may be different in your environment)

vi /etc/zabbix/zabbix_agentd.conf

Add a line like the below one.

UserParameter=mysql.slaves_count,mysql -umysql_backup -pxxxx -e"show all slaves status \G" | grep "Running: No" | wc -l

mysql.slaves_count is an unique identifier. It can be any string. This key will be used in zabbix server.

Now restart the zabbix agent to make changes effective.

Once the agent is restarted go to zabbix User Interface.  Go to Configuration  --> Hosts (and select your host to be monitored) -- > Items

Add new item with Key=mysql.slaves_count  (this is the key gave in agent config file) to the monitored host. Type of the item must be either Zabbix Agent or Zabbix Agent (active).

Zabbix will now start monitoring the item and you will get the value in the monitoring screen.

As I need zabbix to trigger an alert where the value of the out put is greater than zero, I will add a trigger of the host with below expression.
Go to Configuration  --> Hosts (and select your host to be monitored) -- > Trigger
 Expression:

{mysqlslave.myfirm.com:mysql.slaves_count.last(0)}>1

Remember to Give a proper name for the trigger to understand the incident from the trigger name. I gave name as Failed_tread_count_in_{HOST.NAME}

Remember to select proper severity for the trigger so that the expected "actions" to be trirgered. I have pagerduty media type for High severity hence I selected high here. (it depends on your configuration)

REF:
https://www.zabbix.com/documentation/1.8/manual/tutorials/extending_agent