If your organization uses the Mattermost team communications platform, you can configure Horizon to send notices to any Mattermost channel via an incoming webhook. You must configure an incoming webhook in your Mattermost team and do a bit of manual configuration to your Horizon instance.

First, add the following bit of XML to the notificationCommands.xml configuration file (no customization should be needed):

<command binary="false">
  <comment>class for sending messages to a Mattermost team channel for notifications</comment>
  <argument streamed="false">
  <argument streamed="false">

Then create a new file called in the directory with the following contents (customizing values as appropriate):


Restart OpenNMS so that the file will be loaded. Your new mattermost notification command is now available for use in a destination path.

Additional options

The following table lists optional properties that you may use in to customize your Mattermost notifications.

To improve the layout, the property names have been shortened to their final component; you must prepend org.opennms.netmgt.notifd.mattermost. when using them.
Table 1. Additional optional parameters for the Mattermost notification strategy
Parameter Description Default Example


Specify a channel or private group other than the one targeted by the webhook.

Webhook default



The username to associate with the notification posts.




An emoji sequence to use as the icon for the notification posts.

No icon



The URL of an image to use as the icon for the notification posts.

No icon


Should the system-wide proxy settings be used? Configure the system proxy settings via system properties.



Some of the optional configuration parameters are incompatible with some versions of Mattermost. For instance, the channel option is known not to work with Mattermost 3.7.0.

For more information on incoming webhooks in Mattermost, see Mattermost Integration Guide.