How to execute the script(eg: python), based on the key/property from NiFi?

[#1]

Hi, 

I have data(say key) generated from one  of machine learning model, I red this key from kafka and passed to Nifi, based on the key i need to execute the file or script(say python) or bot script( this might restart the system ) from NiFi? .

Plz provide me some input it will be great helpful?