Procedure 13.1. Configuring HTTPD for Nagios

1. Log in as the root user.
2. To change the default password for the user nagiosadmin, execute:

   # htpasswd -c /etc/nagios/passwd nagiosadmin

   Note

   To create a new user, use the following command with the new user's name:

   # htpasswd /etc/nagios/passwd newUserName

3. Update the nagiosadmin email address in /etc/nagios/objects/contacts.cfg

   define contact{
       contact_name   nagiosadmin            ; Short name of user
       [...snip...]
       email          yourName@example.com   ; <<*****CHANGE THIS******
       }
   

4. Verify that the basic configuration is working:

   # nagios -v /etc/nagios/nagios.cfg

   If errors occur, check the parameters set in /etc/nagios/nagios.cfg
5. Ensure that Nagios is started automatically when the system boots.

   # chkconfig --add nagios
   # chkconfig nagios on

6. Start up Nagios and restart httpd:

   # service httpd restart
   # service nagios start

7. Check your Nagios access by using the following URL in your browser, and using the nagiosadmin user and the password that was set in Step 1:

   http://nagiosHostURL/nagios

   ⁠

   

   Figure 13.1. Nagios Login

Procedure 13.2. Configuring Nagios to monitor an OpenStack service

1. Log in as the root user.
2. Write a short script for the item to be monitored (for example, whether a service is running), and place it in the /usr/lib64/nagios/plugins directory.
   For example, the following script checks the number of Compute instances, and is stored in a file named nova-list:

   #!/bin/env bash
   export OS_USERNAME=userName
   export OS_TENANT_NAME=tenantName
   export OS_PASSWORD=password
   export OS_AUTH_URL=http://identityURL:35357/v2.0/
   
   data=$(nova list  2>&1)
   rv=$?
   
   if [ "$rv" != "0" ] ; then
       echo $data
       exit $rv
   fi
   
   echo "$data" | grep -v -e '--------' -e '| Status |' -e '^$' | wc -l

3. Ensure the script is executable:

   # chmod u+x nova-list

4. In the /etc/nagios/objects/commands.cfg file, specify a command section for each new script:

   define command {
           command_line                   /usr/lib64/nagios/plugins/nova-list
           command_name                   nova-list
   }

5. In the /etc/nagios/objects/localhost.cfg file, define a service for each new item, using the defined command. For example:

   define service {
           check_command   nova-list
           host_name       localURL
           name            nova-list
           normal_check_interval   5
           service_description     Number of nova vm instances
           use             generic-service
           }
   

6. Restart nagios using:

   # service nagios restart

Procedure 13.3. Configuring monitoring on a remote machine

1. In the /etc/nagios/nrpe.cfg file, add the central Nagios server IP address in the allowed_hosts line:

   allowed_hosts=127.0.0.1, NagiosServerIP

2. In the /etc/nagios/nrpe.cfg file, add any commands to be used to monitor the OpenStack services. For example:

   command[keystone]=/usr/lib64/nagios/plugins/check_procs -c 1: -w 3: -C keystone-all
   

   Each defined command can then be specified in the services.cfg file on the Nagios monitoring server (refer to Section 13.2.5, “Create Service Definitions for Remote Services”).

   Note

   Any complicated monitoring can be placed into a script, and then referred to in the command definition. For an OpenStack script example, refer to Section 13.2.2, “Configure Nagios to Monitor OpenStack Services”.
3. Next, configure the firewall to allow nrpe traffic.
   For Red Hat Enterprise Linux 6-based systems, complete the following steps:
   1. Open the /etc/sysconfig/iptables file in a text editor.
   2. Add an INPUT rule allowing UDP traffic on port 5666 to this file. The new rule must appear before any INPUT rules that REJECT traffic.

      -A INPUT -p tcp --dport 5666 -j ACCEPT

   3. Save the changes to the /etc/sysconfig/iptables file.
   4. Restart the iptables service for the firewall changes to take effect.

      # service iptables restart

   For Red Hat Enterprise Linux 7-based systems, run the following commands:

   # firewall-cmd --permanent --add-port=5666/udp
   # firewall-cmd --add-port=5666/udp

4. Start the NRPE service:

   # service nrpe start

Procedure 13.4. Creating host definitions through an objects file

1. Log in as the root user.
2. In the /etc/nagios/objects directory, create a hosts.cfg file.
3. In the file, specify a host section for each machine on which an OpenStack service is running and should be monitored:

   define host{
       use linux-server
       host_name remoteHostName
       alias remoteHostAlias
       address remoteAddress
   }

   where:

   • host_name = Name of the remote machine to be monitored (typically listed in the local /etc/hosts file). This name is used to reference the host in service and host group definitions.
   • alias = Name used to easily identify the host (typically the same as the host_name).
   • address = Host address (typically its IP address, although a FQDN can be used instead, just make sure that DNS services are available).
   For example:

   define host{
     host_name     Server-ABC
     alias		OS-ImageServices
     address	192.168.1.254
   }
   

4. In the /etc/nagios/nagios.cfg file, under the OBJECT CONFIGURATION FILES section, specify the following line:

   cfg_file=/etc/nagios/objects/hosts.cfg

Procedure 13.5. Creating service definitions

1. Log in as the root user.
2. In the /etc/nagios/objects/commands.cfg file, specify the following to handle the use of the check_nrpe plugin with remote scripts or plugins:

   define command{
           command_name    check_nrpe
           command_line    $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
    }
   
   

3. In the /etc/nagios/objects directory, create the services.cfg file.
4. In the file, specify the following service sections for each remote OpenStack host to be monitored:

   ##Basic remote checks#############
   ##Remember that remoteHostName is defined in the hosts.cfg file.
   
   define service{
   	use generic-service
   	host_name remoteHostName
   	service_description PING
   	check_command check_ping!100.0,20%!500.0,60%
   }
   
   define service{
   	use generic-service
   	host_name remoteHostName
   	service_description Load Average
   	check_command check_nrpe!check_load
   }
   
   ##OpenStack Service Checks#######
   define service{
   	use generic-service
   	host_name remoteHostName
   	service_description Identity Service
   	check_command check_nrpe!keystone
   }
   

   The above sections ensure that a server heartbeat, load check, and the OpenStack Identity service status are reported back to the Nagios server. All OpenStack services can be reported, just ensure that a matching command is specified in the remote server's nrpe.cfg file.
5. In the /etc/nagios/nagios.cfg file, under the OBJECT CONFIGURATION FILES section, specify the following line:

   cfg_file=/etc/nagios/objects/services.cfg

Procedure 13.6. Verifying the Nagios configuration

1. Log in as the root user.
2. Verify that the updated configuration is working:

   # nagios -v /etc/nagios/nagios.cfg

   If errors occur, check the parameters set in /etc/nagios/nagios.cfg, /etc/nagios/services.cfg, and /etc/nagios/hosts.cfg.
3. Restart Nagios:

   # service nagios restart

4. Log into the Nagios dashboard again by using the following URL in your browser, and using the nagiosadmin user and the password that was set in Step 1:

   http://nagiosHostURL/nagios