Replace gunicorn with waitress (#1614)

This commit replaces the `gunicorn` WSGI server with `waitress`. It
loses the statsd statistics, but gives us peace of mind.

The setup was tested by commenting out the `python manage.py run`
command in `docker-compose.yml`. Note that migrations need to be run for
the index page to work via `podman compose exec web -- python manage.py
migrate`.

Rationale
=========

Over the last few months, our dependency `gunicorn` has received a large amount
of contributions written primarily by the maintainer with close to zero external
review.

None of these implemented features are anything we need: dirty workers,
uWSGI protocol support, control socket, shared memory, ....  Nor do I
ever recall looking for any of these features in it.

The sheer volume of code and the general format of changes also strongly reeks
of LLM authorship or assistance.

Of course, every maintainer is free to do with their software whatever they
wish. But, as with any other dependency, I will evaluate any updates, keeping in
mind that any dependency we have here has full access to our database and API.

We do not need a WSGI server with regular feature development. We need one that
works and is maintained - that is the only requirement. See the linked
issue for more discussion.

Fixes: #1613

Signed-off-by: Johannes Christ <jc@jchri.st>

Author: jchristgit

Dockerfile

@@ -56,7 +56,5 @@ RUN if [ $STATIC_BUILD = "TRUE" ] ; \
   then SECRET_KEY=dummy_value uv run python manage.py distill-local build --traceback --force ; \
 fi
 
-CMD ["gunicorn", "--preload", "-b", "0.0.0.0:8000", \
-     "pydis_site.wsgi:application", "-w", "2", "--statsd-host", \
-     "graphite.default.svc.cluster.local:8125", "--statsd-prefix", "site", \
-     "--config", "file:gunicorn.conf.py"]
+CMD ["waitress-serve", "--listen", "*:8000", \
+     "--max-request-body-size=52428800", "pydis_site.wsgi:application"]

gunicorn.conf.py

@@ -31,7 +31,7 @@ class SiteManager:
     Manages the preparation and serving of the website for local use.
 
     This class is used solely for setting up the development
-    environment. In production, gunicorn is invoked directly
+    environment. In production, the WSGI server is invoked directly
     and migrations are handled in an init container.
 
     Usage:

manage.py

@@ -53,7 +53,7 @@ the website:
   determine _which URLs will lead to which Django views_.
 
 - [`wsgi.py`](./wsgi.py), which serves as an adapter for
-  [`gunicorn`](https://github.com/benoitc/gunicorn),
+  [`waitress`](https://github.com/Pylons/waitress),
   [`uwsgi`](https://github.com/unbit/uwsgi), or other application servers to run
   our application in production. Unless you want to test an interaction between
   our application and those servers, you probably won't need to touch this.

pydis_site/README.md

@@ -13,7 +13,6 @@ dependencies = [
     "django-prometheus==2.4.1",
     "django-simple-bulma==2.6.0",
     "djangorestframework==3.16.0",
-    "gunicorn==24.1.1",
     "httpx==0.28.1",
     "markdown==3.8.2",
     "psycopg[binary]==3.2.9",
@@ -22,6 +21,7 @@ dependencies = [
     "python-frontmatter==1.1.0",
     "pyyaml==6.0.2",
     "sentry-sdk==2.33.0",
+    "waitress==3.0.2",
     "whitenoise==6.9.0",
 ]
 
@@ -76,7 +76,6 @@ select = ["ANN", "B", "C4", "D", "DJ", "DTZ", "E", "F", "ISC", "INT", "N", "PGH"
 "pydis_site/apps/**/tests/test_*.py" = ["ANN", "D"]
 "static-builds/netlify_build.py" = ["T201"]
 "pydis_site/apps/api/tests/test_off_topic_channel_names.py" = ["RUF001"]
-"gunicorn.conf.py" = ["ANN", "D"]
 "pydis_site/apps/api/models/bot/off_topic_channel_name.py" = ["RUF001"]
 
 [tool.taskipy.tasks]