[mod] container: replace uWSGI with Granian (#4820)

* [mod] container: replace uWSGI with Granian

The configuration in Granian is handled with ENVs, much more convenient and practical for updating. The settings have been tested for over two months in a production instance, being usable on small to somewhat large instances without having to modify anything.

It also removes the patch functions and ENVs abstraction from the entrypoint, this makes it possible to run the container with immutable configuration.

In some setups, It may be desired to have the volumes/files under a specific uid/gid (other than searxng:searxng), if the entrypoint has root permissions it will chown automatically on every start, which may not be desired. Explicitly setting the new ENV `FORCE_OWNERSHIP=false` will prevent ownership from being modified.

No manual migration is necessary **unless** the user has changed the default uWSGI configuration or has a very specific setup.

Closes https://github.com/searxng/searxng/issues/4894
Closes https://github.com/searxng/searxng/issues/4818
Closes https://github.com/searxng/searxng/issues/4802

Supersedes https://github.com/searxng/searxng/pull/4596

Related https://github.com/searxng/searxng/discussions/4479

* [mod] docs: add container/granian

All container documentation has been recreated.

A new documentation page has been created for Granian.

* [enh] misc: apply suggestions

Minor documentation changes.

Suggested https://github.com/searxng/searxng/pull/4820#discussion_r2134539259
Suggested https://github.com/searxng/searxng/pull/4820#discussion_r2134538610
Suggested https://github.com/searxng/searxng/pull/4820#discussion_r2134827964
Suggested https://github.com/searxng/searxng/pull/4820#discussion_r2134544300
Suggested https://github.com/searxng/searxng/pull/4820#discussion_r2149387388

---------

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Co-authored-by: Ivan Gabaldon <igabaldon@inetol.net>
Co-authored-by: Markus Heiser <markus.heiser@darmarit.de>

1 files changed, 52 insertions, 0 deletions

diff --git a/docs/admin/installation-granian.rst b/docs/admin/installation-granian.rst
new file mode 100644
index 000000000..06fd064c6
--- /dev/null
+++ b/docs/admin/installation-granian.rst
@@ -0,0 +1,52 @@
+.. _searxng granian:
+
+=======
+Granian
+=======
+
+.. _Options: https://github.com/emmett-framework/granian/blob/master/README.md#options
+.. _Workers and threads: https://github.com/emmett-framework/granian/blob/master/README.md#workers-and-threads
+.. _Backpressure: https://github.com/emmett-framework/granian/blob/master/README.md#backpressure
+.. _Runtime mode: https://github.com/emmett-framework/granian/blob/master/README.md#runtime-mode
+
+.. sidebar:: further reading
+
+   - `Options`_
+   - `Workers and threads`_
+   - `Backpressure`_
+   - `Runtime mode`_
+
+.. note::
+
+   Granian will be the future replacement for :ref:`searxng uwsgi` in SearXNG.
+   At the moment, it's only officially supported in the :ref:`installation
+   container`.
+
+.. _Granian installation:
+
+Installation
+============
+
+We only recommend installing Granian with pip, as officially documented. Run
+the following command in the Python environment of the SearXNG installation:
+
+.. code:: sh
+
+   $ pip install granian
+
+.. _Granian configuration:
+
+Configuration
+=============
+
+.. note::
+
+   It's not advised to modify the amount of workers, expect increased resource
+   usage and potential issues with :ref:`botdetection`.
+
+Granian can be configured via option parameters and environment variables
+(``$GRANIAN_*``).
+
+We provide sane defaults that should fit most use cases, however if you feel
+you should change something, Granian documents all available parameters in the
+`Options`_ section.