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Install Naemon Core on Ubuntu Focal 20.04

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Prepare your system

In this how to, we are going to install all files to /opt/naemon.

If you want to delete Naemon Core, just remove this folder and the systemd config.

All commands needs to run as user root or via sudo.

addgroup --system naemon
adduser --system naemon
adduser naemon naemon

Install dependencies

apt-get update
apt-get install build-essential automake gperf help2man libtool libglib2.0-dev

Download and install Naemon Core

Check for new versions

In this how to I use Naemon 1.2.3. Check if there is a new version available! 

cd /tmp/
wget https://github.com/naemon/naemon-core/archive/v1.2.3.tar.gz
tar xfv v1.2.3.tar.gz
cd naemon-core-1.2.3/

./autogen.sh --prefix=/opt/naemon --with-naemon-user=naemon --with-naemon-group=naemon --with-pluginsdir=/usr/lib/nagios/plugins
make all
make install

mkdir -p /opt/naemon/var/
mkdir -p /opt/naemon/var/cache/naemon
mkdir -p /opt/naemon/var/spool/checkresults
chown naemon:naemon /opt/naemon/var -R

mkdir /opt/naemon/etc/naemon/module-conf.d
chown naemon:naemon /opt/naemon/etc -R

Start Naemon Core (through systemd - recommended)

Due to I had some issues using the default Naemon systemd service configuration I modified the original a bit.

Copy the following to the file /lib/systemd/system/naemon.service using your favorite editor.

Pitfall!

If you want to use Naemon with the Statusengine Broker Module, it is required that the Gearman Job Server is running, BEFORE your Naemon gets started!
So you need to make sure that systemd will start the Gearman Job Server first.
To configure this, replace the AFTER= line in the following systemd configuration with this: 

After=network.target gearman-job-server.service
If not already done, install the Gearman Job Server now! 
apt-get install gearman-job-server

[Unit]
Description=Naemon Monitoring Daemon
Documentation=http://naemon.org/documentation
After=network.target

[Service]
Type=forking
PIDFile=/opt/naemon/var/cache/naemon/naemon.pid
ExecStartPre=/opt/naemon/bin/naemon --verify-config /opt/naemon/etc/naemon/naemon.cfg
ExecStart=/opt/naemon/bin/naemon --daemon /opt/naemon/etc/naemon/naemon.cfg
ExecReload=/bin/kill -HUP $MAINPID
User=naemon
Group=naemon
StandardOutput=journal
StandardError=inherit

[Install]
WantedBy=multi-user.target


systemctl daemon-reload
systemctl start naemon

Now you can check if your Naemon Core is running using systemctl status naemon:

root@focal:/tmp/naemon-core-1.2.3# systemctl status naemon
● naemon.service - Naemon Monitoring Daemon
     Loaded: loaded (/lib/systemd/system/naemon.service; disabled; vendor preset: enabled)
     Active: active (running) since Sun 2021-02-28 09:14:07 UTC; 4s ago
       Docs: http://naemon.org/documentation
    Process: 48031 ExecStartPre=/opt/naemon/bin/naemon --verify-config /opt/naemon/etc/naemon/naemon.cfg (code=exited, status=0/SUCCESS)
    Process: 48032 ExecStart=/opt/naemon/bin/naemon --daemon /opt/naemon/etc/naemon/naemon.cfg (code=exited, status=0/SUCCESS)
   Main PID: 48033 (naemon)
      Tasks: 6 (limit: 2344)
     Memory: 2.3M
     CGroup: /system.slice/naemon.service
             ├─48033 /opt/naemon/bin/naemon --daemon /opt/naemon/etc/naemon/naemon.cfg
             ├─48034 /opt/naemon/bin/naemon --worker /opt/naemon/var/naemon.qh
             ├─48035 /opt/naemon/bin/naemon --worker /opt/naemon/var/naemon.qh
             ├─48036 /opt/naemon/bin/naemon --worker /opt/naemon/var/naemon.qh
             ├─48037 /opt/naemon/bin/naemon --worker /opt/naemon/var/naemon.qh
             └─48051 /opt/naemon/bin/naemon --daemon /opt/naemon/etc/naemon/naemon.cfg

Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]:         Checked 0 service dependencies
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]:         Checked 0 host dependencies
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]:         Checked 5 timeperiods
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Checking global event handlers...
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Checking obsessive compulsive processor commands...
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Checking misc settings...
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Total Warnings: 0
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Total Errors:   0
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 naemon[48031]: Things look okay - No serious problems were detected during the pre-flight check
Feb 28 09:14:07 ubuntu-s-2vcpu-2gb-intel-fra1-01 systemd[1]: Started Naemon Monitoring Daemon.

To make sure that you Naemon will start automatically on boot, you need to enable the systemd configuration:

systemctl enable naemon.service

Install Monitoring Plugins

By default, Naemon will install a sample config with some basic checks. So you need to install the monitoring plugins to get them to work.

apt-get install monitoring-plugins

Setup Logrotate

To avoid, that the size of your naemon.log grows up in the sky you should configure the logrotate daemon.

Modify the file /opt/naemon/etc/logrotate.d/naemon until it fulfill your needs.

Than copy it to /etc/logrotate.d/ to enable the configuration


Congrats! You installed Naemon Core!

Load Statusengine Broker Module

Now you are ready to install and load the Statusengine Broker Module.

Start Naemon in foreground (expert or debugging)

For some reasons it can be useful to run Naemon in foreground.

You can do this with this command /opt/naemon/bin/naemon /opt/naemon/etc/naemon/naemon.cfg

root@focal:/opt/naemon# sudo -u naemon /bin/bash
naemon@focal:/opt/naemon$ /opt/naemon/bin/naemon /opt/naemon/etc/naemon/naemon.cfg

Naemon Core 1.2.3
Copyright (c) 2013-present Naemon Core Development Team and Community Contributors
Copyright (c) 2009-2013 Nagios Core Development Team and Community Contributors
Copyright (c) 1999-2009 Ethan Galstad
License: GPL

Website: http://www.naemon.org
Naemon 1.2.3 starting... (PID=52156)
Local time is Sun Feb 28 09:16:12 UTC 2021
qh: Socket '/opt/naemon/var/naemon.qh' successfully initialized
nerd: Channel hostchecks registered successfully
nerd: Channel servicechecks registered successfully
nerd: Fully initialized and ready to rock!
Successfully launched command file worker with pid 52161
^CCaught 'Interrupt', shutting down...
Retention data successfully saved.
Successfully shutdown... (PID=52156)
Event broker module 'NERD' deinitialized successfully.
Successfully reaped command worker (PID = 52161)
naemon@focal:/opt/naemon$