Set product configuration globally in zope.conf

I have a Zope product that needs to write in a centralized location, across multiple instances. The classic Python solution would be to write a variable in a module and read that location from the code, but this feels unelegant in an environment that uses zc.buildout for deployment. The solution I have found is, as follows:

In buildout.cfg, in the instance part definition, add:

zope-conf-additional =
        mylocation ${buildout:directory}/var/mylocation

Next, inside the product code I have:

from App.config import getConfiguration
import os

conf = getConfiguration()
dest = conf.environment['mylocation']
if not os.path.exists(dest):

There were 2 things that I had to research for this task: reading the global zope configuration (that's done with App.config.getConfiguration()) and the fact that you can't add arbitrary key/values in zope.conf and have to use the <environment> section.