Passing sockets to an emperors vassals via env variables does not appear to work

[traverseda]

I'm trying to create a system where web apps can be easily installed through third-party package managers like pip, basically making it so that users can type pipx install somewebapp then navigate to localhost:8003/somewebapp, all in one pass and with zero configuration needed. uwsgi is the obvious choice for this, but I'm running into some issues getting the emperor to work as described in the docs.

Using uwsgi version 2.0.18 and the documentation here.

Steps to reproduce

mkdir /tmp/apps/
printf "[uwsgi] \nmodule = werkzeug.testapp:test_app" > /tmp/apps/testApp2.ini
printf "[uwsgi] \nmodule = werkzeug.testapp:test_app" > /tmp/apps/testApp2.ini
UWSGI_VASSAL_SOCKET=/tmp/%n.sock uwsgi --emperor /tmp/apps/

This causes the vassal to error with The -s/--socket option is missing and stdin is not a socket.. What I'd expect, going by the documentation, is for it to create 2 new sockets, /tmp/testApp.sock and /tmp/testApp2.sock.

Other attempts. passing arguments like --vassals-include /tmp/vassals-default.ini, cause all the sockets to be named vassals-default.sock which definitely would not work. Using the vassal-set directive in an emperor.ini file has the same problem, all sockets get named emperor.sock.