Thanks to a pull-request from friend of MQTT @zer0c00l, GitHub now has the ability to publish an MQTT message whenever a repository has a change pushed to it.
To get your repository publishing, find your way to its admin page.
From there, under the Service Hooks tab, select the MqttPub hook in the list to bring up the configuration options.
The options speak for themselves, but there are some handy notes provided to help you figure it out. Be sure to check the ‘active’ box before hitting Update Settings.
With that done, you should start to get messages published whenever something is committed to the repository. The message itself is a json blob that contains all of the information about the commit that you could possible want.
You can read more about the contents of the blob on GitHub’s Post-Receive Hooks help page.