Monitoring (Nagios)

https://www.digitalocean.com/community/tutorials/how-to-install-nagios-4-and-monitor-your-servers-on-ubuntu-16-04

Nagios

Configure Nagios server

• Add users and groups

sudo useradd nagios
sudo groupadd nagcmd
sudo usermod -a -G nagcmd nagios

• Install system requirements

sudo usermod -a -G nagcmd nagios
sudo apt-get install build-essential libgd2-xpm-dev openssl libssl-dev unzip

• Install Nagios

cd ~
curl -L -O http://repos.rra.lan/nagios/nagios-4.3.4.tar.gz
tar zxf nagios-*.tar.gz
cd nagios-*
./configure --with-nagios-group=nagios --with-command-group=nagcmd
make all
sudo make install
sudo make install-commandmode
sudo make install-init
sudo make install-config

• Enable the nagios conf

sudo /usr/bin/install -c -m 644 sample-config/httpd.conf /etc/apache2/sites-available/nagios.conf

• Add group nagcmd to www-data

sudo usermod -G nagcmd www-data

• Installing nrpe plugin

cd ~
curl -L -O http://repos.rra.lan/nagios/nrpe-3.2.1.tar.gz
tar zxf nrpe-*.tar.gz
cd nrpe-*
./configure
make check_nrpe
sudo make install-plugin

• Configure Nagios

sudo nano /usr/local/nagios/etc/nagios.cfg

Uncomment this line by deleting the # character from the front of the line:
cfg_dir=/usr/local/nagios/etc/servers

sudo mkdir /usr/local/nagios/etc/servers
sudo nano /usr/local/nagios/etc/objects/contacts.cfg

Find the email directive and replace its value with your own email address.

sudo nano /usr/local/nagios/etc/objects/commands.cfg

Add the following to the end of the file to define a new command called check_nrpe.
define command{
       command_name check_nrpe
       command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}

sudo a2enmod rewrite
sudo a2enmod cgi

• Create nagios amdin

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

• Enable nagios conf

sudo ln -s /etc/apache2/sites-available/nagios.conf /etc/apache2/sites-enabled/

• Edit nagios conf

sudo nano /etc/apache2/sites-available/nagios.conf

Uncomment both occurrances by removing the # symbol.
#  SSLRequireSSL

• Restart Apache

sudo systemctl restart apache2

• Create service

sudo nano /etc/systemd/system/nagios.service

[Unit]
Description=Nagios
BindTo=network.target

[Install]
WantedBy=multi-user.target

[Service]
Type=simple
User=nagios
Group=nagios
ExecStart=/usr/local/nagios/bin/nagios /usr/local/nagios/etc/nagios.cfg

sudo systemctl enable /etc/systemd/system/nagios.service
sudo systemctl start nagios

Connect server to Nagios

On the client

• Add user nagios

sudo useradd nagios

• Install system requirements

sudo apt-get update
sudo apt-get install build-essential libgd2-xpm-dev openssl libssl-dev unzip

• Install nagios-plugins

cd ~
curl -L -O http://repos.rra.lan/nagios/nagios-plugins-2.2.1.tar.gz
tar zxf nagios-plugins-*.tar.gz
cd nagios-plugins-*
./configure --with-nagios-user=nagios --with-nagios-group=nagios --with-openssl
make
sudo make install

• Install nrpe

cd ~
curl -L -O http://repos.rra.lan/nagios/nrpe-3.2.1.tar.gz
tar zxf nrpe-*.tar.gz
cd nrpe-*
./configure --enable-command-args --with-nagios-user=nagios --with-nagios-group=nagios --with-ssl=/usr/bin/openssl --with-ssl-lib=/usr  /lib/x86_64-linux-gnu
make all
sudo make install
sudo make install-config
sudo make install-init

sudo nano /usr/local/nagios/etc/nrpe.cfg

allowed_hosts=127.0.0.1,::1,horus.rra.lan

sudo systemctl start nrpe.service
sudo systemctl status nrpe.service
sudo systemctl enable nrpe.service

• To add a new service (it is an example of ow to add a check_disk service):

sudo nano /usr/local/nagios/etc/nrpe.cfg

server_address=[monitored_server_private_ip]
command[check_vda1]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/vda1
sudo systemctl restart nrpe.service

On Nagios

On the server

---

sudo nano /usr/local/nagios/etc/servers/your_monitored_server_host_name.cfg

define host {
       use                             linux-server  # linux-server | 
       host_name                       your_monitored_server_host_name # Host name from DNS
       alias                           My client server  # Description
       address                         your_monitored_server_private_ip # Host DNS or IP
       max_check_attempts              5
       check_period                    24x7
       notification_interval           30
       notification_period             24x7
}

define service {
       use                             generic-service
       host_name                       your_monitored_server_host_name
       service_description             CPU load
       check_command                   check_nrpe!check_load
}

sudo systemctl restart nagios

How to check nagios connection to a client

/usr/local/nagios/libexec/check_nrpe -H [host]

GitLab

At the GitLab server

cd /usr/local/nagios/libexec  # /usr/lib/nagios/plugins/  for installations from package
sudo -u nagios -H wget http://repos.rra.lan/nagios/check_scripts/check_gitlab
sudo -u nagios -H wget http://repos.rra.lan/nagios/check_scripts/check_mem
sudo chmod 744 check_gitlab
sudo chmod 744 check_mem
sudo apt install ruby dc

sudo nano /usr/local/nagios/etc/nrpe.cfg
### GitLab ###
command[check_mem]=/usr/local/nagios/libexec/check_mem -w 80 -c 90 -W 40 -C 60 
command[check_gitlab_health]=/usr/local/nagios/libexec/check_gitlab -m health -s https://localhost -k -t <token_from: https://git.rra.lan/admin/health_check>
command[check_gitlab_services]=/usr/local/nagios/libexec/check_gitlab -m services -s https://localhost -k -t <token_from: https://git.rra.lan/admin/health_check>
# command[check_gitlab_cipipeline]=/usr/local/nagios/libexec/check_gitlab -m ci-pipeline -s https://localhost -k -t <token_from: https://git.rra.lan/admin/health_check>
# command[check_gitlab_cirunner]=/usr/local/nagios/libexec/check_gitlab -m ci-runner -s https://localhost -k -t <token_from: https://git.rra.lan/admin/health_check>

sudo service nrpe restart

At the Nagios server

sudo nano /usr/local/nagios/etc/servers/gitlab.rra.lan.cfg

define host {
       use                             linux-server
       host_name                       git.rra.lan
       alias                           GitLab VPN
       address                         git.rra.lan
       max_check_attempts              5
       check_period                    24x7
       notification_interval           30
       notification_period             24x7
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Load
        check_command                   check_nrpe!check_load
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Root Partition
        check_command                   check_nrpe!check_hd_root
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Memory
        check_command                   check_nrpe!check_mem
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Swap
        check_command                   check_nrpe!check_swap
}


define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Health
        check_command                   check_nrpe!check_gitlab_health
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Health
        check_command                   check_nrpe!check_gitlab_health
}

define service {
        use                             generic-service
        host_name                       git.rra.lan
        service_description             GitLab Services
        check_command                   check_nrpe!check_gitlab_services
}


sudo systemctl restart nagios

ChiChi

At ChiChi.rra.lan

• Follow the Install nrpe instructions
• As nagios user:

Sources

https://www.digitalocean.com/community/tutorials/how-to-install-nagios-4-and-monitor-your-servers-on-ubuntu-16-04
https://gitlab.com/6uellerBpanda/check_gitlab