I very recently moved this weblog to a new host, and in the process finally changed from Apache running mod_wsgi to nginx with uWSGI and supervisor (well, at least for the Python based web apps, as dammIT is a flat site). I'm using isso as commenting system, which runs as an application in uWSGI, using a socket, and is managed by uWSGI. This is all fine, dandy, and documented by their documentation, but running it in a subdirectory (in the URL) is not. After some hair pulling and numerous web searches, I arrived at this working configuration:

location /comments {
    include uwsgi_params;
    uwsgi_param HTTP_X_SCRIPT_NAME /comments;
    uwsgi_pass unix:/var/local/socket/isso.sock;
}

Mind the line with HTTP_X_SCRIPT_NAME here, as that's what tells isso it runs under that subdirectory instead of in the webroot.

For completeness, the uWSGI configuration I use is as follows:

[uwsgi]
# use Python 3.7 plugin; change to python36 or similar, depending on the Python version in your venv
plugins = python37
project = isso
base = /srv/www/isso

# the virtualenv (full path), in which isso is installed through `pip install isso`
home = %(base)/venv
# wsgi file
module = isso.run

env = ISSO_SETTINGS=/srv/www/isso/dammit.nl.ini
#spooler = %d/mail

master = true
# maximum number of worker processes
processes = 4

socket = /var/local/socket/%(project).sock
chmod-socket = 666
# clear environment on exit
vacuum = true

# make sure that uWSGI doesn't hard kill the app on termination
die-on-term = true