Now that you've learned how to fire our own custom events, it's time to learn how to react to those events. To accomplish this, we will use a tool, fittingly named the reactor.

The reactor is configured in two parts. The first piece is in the master configuration file and defines which events will trigger which reactor files. The second part consists of the reactor files themselves, which define the actions to be taken when reacting to events, and which are similar to state files.

Here are the lines we will be adding to our master configuration file (/etc/salt/master):

reactor:
  - 'salt/custom/*':
    - salt://reactor.sls

Note that globbing is used to target multiple events with a single configuration. Thus, we are now set up such that when the master receives any event that has a tag that starts with salt/custom/, the master will execute the reactor.sls reactor file from our Salt files in /srv/salt.