No matter how well we set up our infrastructure, eventually something will go wrong that needs to be fixed. When that happens, the first step is to check the logs for errors and warnings. In this hands-on lab, we will create a Nagios service that monitors the logs for errors and warnings using the `check_log` plugin.
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Define Two Command Objects that Check the Logs **/var/log/messages** for Errors and Warnings in **/usr/local/nagios/etc/objects/commands.cfg**
Add the following text to the
commands.cfgfile:define command { command_name check_log_error command_line /usr/local/nagios/libexec/check_log -F /var/log/messages -O /home/nagios/check_log.error -q "error" }define command { command_name check_log_warning command_line /usr/local/nagios/libexec/check_log -F /var/log/messages -O /home/nagios/check_log.warning -q "warning" }
- Define Two Services that Use the Commands
Add the following text to the
localhost.cfgfile:define service { use local-service host_name localhost service_description Check Log Error check_command check_log_error }define service { use local-service host_name localhost service_description Check Log Warnings check_command check_log_warning }
- Give the `nagios` User Read Permissions for `/var/log/messages`
- Run the following command:
sudo setfacl -R -m u:nagios:r-- /var/log/messages
- Run the following command:
- Restart and Log In to the Nagios Server
- Restart the Nagios server.
sudo systemctl restart nagios - Navigate to http://NAGIOS_SERVER_IP/nagios, and log in with the following credentials:
- User Name: nagiosadmin
- Password: BlaBla321
- Navigate to Services.
- Reschedule the checks for the two services to run 10-20 seconds from the current server time.
- Verify that there are no errors under Status Information.
- Restart the Nagios server.
