Docker: add UWSGI_WORKERS and UWSGI_THREAD environment variables (#2992)

* Docker: add UWSGI_WORKERS and UWSGI_THREAD.

UWSGI_WORKERS specifies the number of process.
UWSGI_THREADS specifies the number of threads.

The Docker convention is to specify the whole configuration
through environment variables. While not done in SearXNG, these two
additional variables allows admins to skip uwsgi.ini

In additional, https://github.com/searxng/preview-environments starts Docker
without additional files through searxng-helm-chat.
Each instance consumes 1Go of RAM which is a lot especially when there are a
lot of instances / pull requests.

* [scripts] add environments UWSGI_WORKERS and UWSGI_THREADS

- UWSGI_WORKERS specifies the number of process.
- UWSGI_THREADS specifies the number of threads.

Templates for uwsgi scripts can be tested by::

    UWSGI_WORKERS=8 UWSGI_THREADS=9 \
      ./utils/searxng.sh --cmd\
      eval "echo \"$(cat utils/templates/etc/uwsgi/*/searxng.ini*)\""\
      | grep "workers\|threads"

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

---------

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Co-authored-by: Markus Heiser <markus.heiser@darmarit.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/docs/admin/installation-docker.rst b/docs/admin/installation-docker.rst
index c667c4f4..09471891 100644
--- a/docs/admin/installation-docker.rst
+++ b/docs/admin/installation-docker.rst
@@ -92,6 +92,9 @@ instance using `docker run <https://docs.docker.com/engine/reference/run/>`_:
                 searxng/searxng
    2f998.... # container's ID
 
+The environment variables UWSGI_WORKERS and UWSGI_THREADS overwrite the default
+number of UWSGI processes and UWSGI threads specified in `/etc/searxng/uwsgi.ini`.
+
 Open your WEB browser and visit the URL:
 
 .. code:: sh