Create a file in etc/featuresBoot.d/flows.boot
sudo vi etc/featuresBoot.d/flows.boot
Add the following features to Sentinel on startup
sentinel-jsonstore-postgres
sentinel-blobstore-noop
sentinel-jms
sentinel-flows
Connect to the Karaf shell via SSH
ssh -p 8301 admin@localhost
Configure Sentinel tracing, REST and ActiveMQ endpoints
config:edit org.opennms.sentinel.controller
config:property-set location SENTINEL(1)
config:property-set id 00000000-0000-0000-0000-000000ddba11(2)
config:property-set http-url http://core-instance-ip:8980/opennms(3)
config:property-set broker-url failover:tcp://my-activemq-ip:61616(4)
config:update
1 A location string is required and is used only for tracing
2 Unique identifier is used as service name only for tracing
3 Base URL for the web UI which provides the REST endpoints
4 URL which points to ActiveMQ broker.
Configure the credentials and exit Karaf shell
opennms:scv-set opennms.http my-sentinel-user my-sentinel-password(1)
opennms:scv-set opennms.broker my-sentinel-user my-sentinel-password(2)
1 Set the credentials for the REST endpoint created in your Horizon Core instance
2 Set the credentials for the ActiveMQ message broker
The credentials are encrypted on disk in etc/scv.jce.

Exit the Karaf Shell with Ctrl+d

Restart the Sentinel to apply the configuration
sudo systemctl restart minion
Verify configuration with running the health-check
opennms:health-check
Ensure features are installed and work properly
Verifying the health of the container

Verifying installed bundles                    [ Success  ]
Retrieving NodeDao                             [ Success  ]
Connecting to JMS Broker                       [ Success  ]
Connecting to ElasticSearch ReST API (Flows)   [ Success  ]
Connecting to OpenNMS ReST API                 [ Success  ]

=> Everything is awesome