https://www.digitalocean.com/community/tutorials/how-to-monitor-hosts-and-services-with-icinga-on-ubuntu-16-04
https://computingforgeeks.com/how-to-install-icinga2-monitoring-tool-on-ubuntu-18-04-lts/
https://www.alibabacloud.com/blog/how-to-install-and-configure-icinga2-monitoring-tool-on-ubuntu-16-04_495269
https://zyradyl.moe/2015/09/07/Icinga2-Tutorial-Part-4/
Pour Ubuntu 20.04
apt-get update && apt-get install -y curl
curl https://packages.icinga.com/icinga.key | apt-key add -
echo "deb http://packages.icinga.com/ubuntu icinga-$(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/icinga2.list
echo "deb-src http://packages.icinga.com/ubuntu icinga-$(lsb_release -sc) main" | sudo tee -a /etc/apt/sources.list.d/icinga2.list
apt-get update && apt-get install -y icinga2 && icinga2 node wizard
https://git.linuxfabrik.ch/linuxfabrik/monitoring-plugins