I´ve already pointed out here, that you can easily restart a replication. But you have to know that the replication isn´t working. Instead of continuously typing "CHECK SLAVE STATUS\G" in mysql i´ve decided to use nagios for that. If something is wrong, i get a mail and a notification in firefox.
For the monitoring i use check_mysql_health.
You can do much more with it. But this describes the replication-monitoring. 😉
At the end slave-io (is the IO-thread running?), slave-sql (is the SQL-thread running?), and slave-lag (delay between the servers) will be checked.
My different nagios-configs for the localohost are stored in /usr/local/nagios/etc/objects/localhost. Nagios loads all configs on start, if the folder is defined in /usr/local/nagios/etc/nagios.cfg
cfg_dir=/usr/local/nagios/etc/objects/localhost
The mysql-checks are defined in /usr/local/nagios/etc/objects/localhost/mysql.cfg.
define command{
command_name check_mysql_health
command_line $USER1$/check_mysql_health -mode $ARG1$ --username $USER3$ --password $USER4$ --warn $ARG2$ --crit $ARG3$ --hostname $HOSTNAME$
}
define service{
use important-service
service_description MYSQL slave-io
host_name obelix.schaal-24.de
check_command check_mysql_health!slave-io-running
}
define service{
use important-service
service_description MYSQL slave-sql
host_name obelix.schaal-24.de
check_command check_mysql_health!slave-sql-running
}
define service{
use important-service-graph
service_description MYSQL slave-lag
host_name obelix.schaal-24.de
check_command check_mysql_health!slave-lag!10!60
}
The values for $USERX$ are stored in /usr/local/nagios/etc/resource.cfg:
# Sets $USER1$ to be the path to the plugins
$USER1$=/usr/local/nagios/libexec
# mysql-passwords
$USER3$=nagios
$USER4$=SECRET_PASSWORD
I use a new user for the checks, since he only needs some rights for the sql-checks and i can easily check different sql-servers from nagios without changing the configfiles too much.
important-service and important-service-graph are extensions to the generic-service and are also defined in /usr/local/nagios/etc/objects/templates.cfg
define service{
name important-service
use generic-service
max_check_attempts 3
normal_check_interval 1
retry_check_interval 1
register 0
}
define service{
name important-service-graph
use important-service
notes Graph
notes_url /nagios/display_nagios_info.php?name1=$HOSTNAME$&name2=$SERVICEDESC$
}
To monitor a remote sql-server just change the hostname, since the pluging connects direct to mysql. There is no need for nrpe or anything else.
define service{
use important-service
service_description MYSQL slave-io
host_name idefix.schaal-24.de
check_command check_mysql_health!slave-io-running
}
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