Salt Event System

Salt 0.9.10 introduced the Salt Event System. This system is used to fire off events enabling third party applications or external processes to react to behavior within Salt.

The event system is comprised of a few components, the event sockets which publish events, and the event library which can listen to events and send events into the salt system.

Listening for Events

The event system is accessed via the event library and can only be accessed by the same system user that Salt is running as. To listen to events a SaltEvent object needs to be created and then the get_event function needs to be run. The SaltEvent object needs to know the location that the Salt unix sockets are kept. In the configuration this is the sock_dir option. The sock_dir option defaults to "/var/run/salt/master" on most systems.

The following code will check for a single event:

import salt.utils.event

event = salt.utils.event.MasterEvent('/var/run/salt/master')

data = event.get_event()

Events will also use a "tag". A "tag" allows for events to be filtered. By default all events will be returned, but if only authentication events are desired, then pass the tag "auth". Also, the get_event method has a default poll time assigned of 5 seconds, to change this time set the "wait" option. This example will only listen for auth events and will wait for 10 seconds instead of the default 5.

import salt.utils.event

event = salt.utils.event.MasterEvent('/var/run/salt/master')

data = event.get_event(wait=10, tag='auth')

Instead of looking for a single event, the iter_events method can be used to make a generator which will continually yield salt events. The iter_events method also accepts a tag, but not a wait time:

import salt.utils.event

event = salt.utils.event.MasterEvent('/var/run/salt/master')

for data in event.iter_events(tag='auth'):
    print(data)