Install OpenJDK 11 JRE runtime
sudo dnf -y install java-11-openjdk-headless
Add repository and import GPG key
sudo dnf -y install https://yum.opennms.org/repofiles/opennms-repo-stable-rhel8.noarch.rpm
sudo rpm --import https://yum.opennms.org/OPENNMS-GPG-KEY
Installing the of Horizon Sentinel
sudo dnf -y install opennms-sentinel
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. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade.
Disable auto updates for Horizon Sentinel
sudo dnf config-manager --disable opennms-repo-stable-*
Verify directory structure with the tree command
sudo dnf -y install tree
tree /opt/sentinel -L 1
Directory structure after successful installation
/opt/sentinel
├── bin
├── COPYING
├── deploy
├── etc
├── lib
└── system
Enable Horizon Sentinel on system boot and start immediately
sudo systemctl enable --now sentinel