Use Varstack data as a Pillar source
Using varstack in Salt is fairly simple. Just put the following into the config file of your master:
ext_pillar: - varstack: /etc/varstack.yaml
Varstack will then use /etc/varstack.yaml to determine which configuration data to return as pillar information. From there you can take a look at the README of varstack on how this file is evaluated.
Parse varstack data and return the result