[yocto] adding avocado to custom image

[Francesco]

Hello everyone,

I'm trying to install a python package and its additional plugins to my 
custom image. These plugins are stored in a directory within the 
package's folder named optional_plugins. Plugins can easily be installed 
using the command python setup.py install from within the plugin folder.

I successfully installed the main package using a custom recipe and 
luckily it works fine on the built image. Unfortunately, none of the 
optional_plugins I tried to install, are instead available on the image.

My question is, how am I supposed to install these plugins from my 
recipe considering that they need to be installed running python 
setup.py install?

I am quite new to yocto, any suggestion is appreciated.

Thanks.

Frank.