OP5 Monitor - How to monitor FreeBSD using NRPE

Introduction

This HOWTO will give you the tools you need to monitor a FreeBSD 13 server using NRPEv3. The following has been tested on FreeBSD 13, using OP5 Monitor 8.4.0, but could work on newer versions too.

Note that not all the example checks will be of use in all cases. Adapt to your needs.

Step-by-step guide

Using FreeBSD 12 or 13, do the following:

1. Install net-mgmt/nrpe3 from the ports collection, using your preferred method. We will use the binary package in this example.
   
   1. Installing net-mgmt/nrpe3

      # pkg install net-mgmt/nrpe3

2. Edit the nrpe configurations file /usr/local/etc/nrpe.cfg and modify the following line:
   
   1. /usr/local/etc/nrpe.cfg

      allowed_hosts=127.0.0.1,::1

      Add any IP that will be connecting. If you are running a single Monitor node, then use that IP. If you are using a distributed system, make sure to add the IP:s of all nodes that will connect. In my case, it looks like this:

   2. /usr/local/etc/nrpe.cfg

      allowed_hosts=127.0.0.1,::1,172.27.86.228,172.27.86.229,172.27.86.230,172.27.86.231

3. Add a custom configuration file to include:

   1. /usr/local/etc/nrpe.cfg

      include=/usr/local/etc/op5/nrpe.cfg

4. Create the directory:

   1. # mkdir -p /usr/local/etc/op5

5. Create the configuration file with the following contents, modified to your needs:

   1. /usr/local/etc/op5/nrpe.cfg

      # op5-nrpe command configuration file
      
      command[users]=/usr/local/libexec/nagios/check_users -w 3 -c 6
      command[check_load]=/usr/local/libexec/nagios/check_load -w 6,5,4 -c 12,10,8
      command[swap]=/usr/local/libexec/nagios/check_swap -w 20% -c 10%
      command[root_disk]=/usr/local/libexec/nagios/check_disk -w 20% -c 10% -p / -m
      command[usr_disk]=/usr/local/libexec/nagios/check_disk -w 20% -c 10% -p /usr -m
      command[var_disk]=/usr/local/libexec/nagios/check_disk -w 20% -c 10% -p /var -m
      command[zombie_procs]=/usr/local/libexec/nagios/check_procs -w 5 -c 10 -s Z
      command[total_procs]=/usr/local/libexec/nagios/check_procs -w 150 -c 200
      command[proc_cron]=/usr/local/libexec/nagios/check_procs -w 1: -c 1:5 -C cron
      command[proc_syslogd]=/usr/local/libexec/nagios/check_procs -w 1: -c 1:2 -C syslogd
      command[mem]=/usr/local/bin/perl /usr/local/libexec/nagios/custom/check_mem.pl -u -w 85 -c 95
      command[updates]=/usr/local/libexec/nagios/custom/check_freebsd_version
      command[zfs_zroot]=/usr/local/libexec/nagios/custom/check_zfs --nosudo zroot

6. Create a directory for custom nrpe check commands:

   1. /usr/local/libexec/nagios/custom/

      # mkdir -p /usr/local/libexec/nagios/custom

7. Download a few custom open-source check plugins and put the in the previously created folder /usr/local/libexec/nagios/custom:

   1. /usr/local/libexec/nagios/custom/

      # fetch --no-verify-peer -o /usr/local/libexec/nagios/custom/check_freebsd_version https://raw.githubusercontent.com/frlen/nagios-plugins/master/check_freebsd_version
      # fetch --no-verify-peer -o /usr/local/libexec/nagios/custom/check_mem.pl https://raw.githubusercontent.com/justintime/nagios-plugins/master/check_mem/check_mem.pl
      # fetch --no-verify-peer -o /usr/local/libexec/nagios/custom/check_zfs https://raw.githubusercontent.com/zlacelle/nagios_check_zfs_linux/master/check_zfs.py
      # chmod +x /usr/local/libexec/nagios/custom/check*
      # pkg install -y python sudo
      # sed -i.bak 's/usr\/bin/usr\/local\/bin/' /usr/local/libexec/nagios/custom/check_zfs
      # rm /usr/local/libexec/nagios/custom/check_zfs.bak
      # echo "nagios ALL=NOPASSWD: /sbin/zfs" > /usr/local/etc/sudoers.d/check_zfs

8. Enable and start the NRPE3 service:

   1. nrpe3

      # service nrpe3 enable
      # service nrpe3 start

9. Now you can create your own services in the Monitor GUI using the pre-defined checks above! Use check_nrpe as the check_command, and put the name of the commands as arguments. An example below: