This example install mercurial as a web service.

apt install mercurial uwsgi-core uwsgi-plugin-python3 python3-legacy-cgi

Application

foobar.py

def application(env, start_response):
    start_response('200 OK', [('Content-Type','text/html')])
    return [b"Hello World"]

Server

uwsgi --plugins http,python3 --http :9090 --wsgi-file foobar.py

Client

$ telnet 127.0.0.1 9090
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
HEAD / HTTP/1.0

HTTP/1.0 200 OK
Content-Type: text/html

Hello World

/var/www/cgi-bin/hgweb.wsgi

config = b"/var/www/repos/WWW.EXAMPLE.COM/hgweb.config"
import os
os.environ["HGENCODING"] = "UTF-8"
import cgitb; cgitb.enable()
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb
application = hgweb(config)

/var/www/repos/WWW.EXAMPLE.COM/hgweb.config

[collections]
/var/www/repos/WWW.EXAMPLE.COM = /var/www/repos/WWW.EXAMPLE.COM

[web]
staticurl = /static/
allow_archive = gz

http

#! /bin/bash

#LOG
exec 2>&1
ulimit -l unlimited
ulimit -i unlimited
ulimit -q unlimited
ulimit -n 8192
ulimit -aH

#RUN
export TZ="UTC"
exec /bin/uwsgi --die-on-term --plugins http,python3 --http :9090 --master --processes 4 --threads 2 --uid=www-data --gid=www-data --wsgi-file /var/www/cgi-bin/hgweb.wsgi

UWSGI

#! /bin/bash

#LOG
exec 2>&1
ulimit -l unlimited
ulimit -i unlimited
ulimit -q unlimited
ulimit -n 8192
ulimit -aH

#RUN
export TZ="UTC"
mkdir -p /run/uwsgi
chown -R www-data:www-data /run/uwsgi
exec /bin/uwsgi --die-on-term --plugins python3 --uwsgi-socket /run/uwsgi/hgweb.sock --master --processes 4 --threads 2 --uid=www-data --gid=www-data --wsgi-file /var/www/cgi-bin/hgweb.wsgi

...
        location / {
                uwsgi_pass unix:/run/uwsgi/hgweb.sock;
                include uwsgi_params;

                limit_except GET HEAD {
                        auth_basic "Login";
                        auth_basic_user_file /var/www/private/htpasswd;
                }
        }

        location /static/ {
                alias /usr/lib/python3/dist-packages/mercurial/templates/static/;
                expires 30d;
        }
...

No promises that this is the correct way of doing it.

/etc/systemd/system/hgweb.service

[Service]
Type=simple
ExecStart=/opt/etc/hgweb.sh
Restart=on-failure
RestartSec=5
KillMode=process

[Install]
WantedBy=multi-user.target

/opt/etc/hgweb.sh

#! /bin/sh
mkdir -p /run/uwsgi
chown -R www-data:www-data /run/uwsgi
exec /bin/uwsgi --die-on-term --plugins python3 --uwsgi-socket /run/uwsgi/hgweb.sock --master --processes 4 --threads 2 --uid=www-data --gid=www-data --wsgi-file /var/www/cgi-bin/hgweb.wsgi

Enable and run

systemctl enable hgweb.service
systemctl start hgweb.service

NGINX setup

UWSGI