Install GnuPG and add OpenNMS repository GPG key sudo apt -y install gnupg sudo apt-key adv --fetch-keys https://debian.opennms.org/OPENNMS-GPG-KEY Add Apt repository sudo apt -y install software-properties-common sudo add-apt-repository -s 'deb https://debian.opennms.org stable main' sudo apt update You can safely ignore the message regarding conflicting distributions (expected stable but got opennms-xx). Install OpenNMS Horizon with built-in dependencies sudo apt -y install opennms Install R packages for trending and forcasting (optional) If you want time series trending and forecast functions you must install the R project packages. The additional download size for packages is ~134 MB. sudo apt -y install r-recommended Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. We recommend that you exclude the Horizon packages from update except when you plan perform an upgrade. sudo apt-mark hold libopennms-java \ libopennmsdeps-java \ opennms-common \ opennms-db Verify directory structure with the tree command sudo apt -y install tree tree /usr/share/opennms -L 1 Directory structure after successful installation /usr/share/opennms ├── bin ├── data ├── deploy ├── etc -> /etc/opennms ├── jetty-webapps ├── lib -> ../java/opennms ├── logs -> /var/log/opennms ├── share -> /var/lib/opennms └── system