What’s New in OpenNMS Horizon 29

System Requirements

  • Java 11: OpenNMS Horizon 29 runs on JDK 11.

  • PostgreSQL 10 or higher: Horizon 29 requires any supported version of PostgreSQL from 10 up to (and including) 14.

Breaking Changes

Running as Non-Root

By default, OpenNMS now runs as the opennms user rather than root.

If you are upgrading from a version of OpenNMS Horizon older than 29, you will have to fix the ownership of your files.

Since many OpenNMS instances are very large with thousands or even millions of RRD and similar data files in $OPENNMS_HOME/share, we decided not to change ownership automatically upon package upgrade.

The OpenNMS installer will detect if you need to fix the ownership of your files and warn you to run the script to fix permissions ($OPENNMS_HOME/bin/fix-permissions) in this case.

If you wish to revert to the previous behavior, create an $OPENNMS_HOME/etc/opennms.conf file if it doesn’t already exist, and set RUNAS.


Additional configuration needed when using Kafka/gRPC for Minion communication.

The Twin API has replaced the OpenNMS REST API for synchronizing Trapd configuration updates. Additional settings are needed on both Minion and Horizon to enable Twin when not using the ActiveMQ message broker.

Refer to the deployment section in the documentation for details.

SQS Minion IPC Support Dropped

Support for Amazon SQS for Minion communication has been removed. We recommend to instead use Kafka for use cases that require horizontal scaling of Minion communication.

Time Series Integration Layer Changes

The Time Series integration layer has gone through a number of big improvements to reduce the complexity and cardinality of metadata and tags.

  • Time series plugins need to be compatible with OIA 0.6.x.

  • Resource level string attributes are now also stored via the plugin in the respective time series database. The timeseries_meta table which previously stored this metadata has been removed. There is no migration; string values are generally updated on the next poll.

New Features and Improvements

Flows and Nephron

Nephron and flow processing have gone through a number of major enhancements.

  • Flow metadata has been tuned and redundancy has been removed, resulting in less data being stored per update.

  • Elasticsearch persistence has been improved to support batching updates.

  • The flow classification engine has been almost entirely rewritten to be considerably more performant when processing large rulesets.

  • Support has been added for persisting flows to Cortex.


The Minion continues to receive improvements in performance and features, most notably the addition of a new API (the "Twin API"), which pushes configuration to Minion over RPC, reducing the amount of data that needs to be passed over the wire.

The first subsystem to adopt this new API is SNMPv3 auth data, so the Minion no longer needs to make a REST call to the OpenNMS core. Over time, all configuration information will be migrated to this new API.

Polling and Metadata


GeoIP Provisioning Adapter

You can use the GeoIP Provisioning Adapter to enrich a node’s asset data with location information. It uses the GeoIP2 Databases from MaxMind to look up longitude/latitude values for a given IP address.



  • A ton of work has gone into cleaning up, rearranging, and standardizing terms in the documentation.

  • A bunch of additional REST APIs are now documented through OpenAPI.

Important Internal Changes

  • Kafka components have been updated to version 2.8.0

  • Our embedded Karaf has been updated to version 4.3.2