Enable tracing with Jaeger on Core instance by installing the opennms-core-tracing-jaeger feature and creating a configuration file with the Jaeger specific settings.

Configurations has to be made in the etc directory relative to the Horizon Core home directory. Depending on your operating system the home directory is in /usr/share/opennms for Debian/Ubuntu or /opt/opennms for CentOS/RHEL.
Create a file to load the tracing feature on startup
sudo vi etc/featuresBoot.d/jaeger.boot
Add the Jaeger feature and save the file
opennms-core-tracing-jaeger
Uninstalling the opennms-core-tracing-jaeger feature at runtime is not yet supported. To disable tracing with Jaeger, remove the reference from the features boot file and restart the Core.
Create a configuration file for tracing settings
sudo vi etc/opennms.properties.d/jaeger.properties
Configure tracing with Jaeger
org.opennms.core.tracer=jaeger(1)
JAEGER_AGENT_HOST=my-jaeger-host(2)
1 Set Jaeger as the tracing implementation
2 Replace the my-jaeger-host with your Jaeger instance where you collect the tracing information
Available configuration options are listed in the Jaeger Core Readme.
The Jaeger service name is the Instance-ID of the Core instance.
Restart Horizon Core instance to apply the changes
sudo systemctl restart opennms