How to parse YAML MIME type in PHP

Good afternoon all, I am trying to catch data in my application which originates from a Puppet Master server (Puppet open source version 4.9). The Puppet Server has the ability to process reports from all of it’s clients and send them over to a destination via an HTTP POST as MIME type application/x-yaml. I have configured the Puppet Server to send data to my application server. I see the traffic coming into the my application server from the Puppet Master Server (via tcpdump). I also see within my application that some POST data is arriving, however, I don’t know how to catch as parse it. When I try to dump the $_POST data, it reads empty. I am using Yii2 as the application framework. Would anyone know how to catch this data and parse it for insertion into a database? Thank you -cs