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>

8 files changed, 25 insertions, 3 deletions

diff --git a/Dockerfile b/Dockerfile
index 053ab123a..d08d681c5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -15,7 +15,9 @@ ENV INSTANCE_NAME=searxng \
     MORTY_KEY= \
     MORTY_URL= \
     SEARXNG_SETTINGS_PATH=/etc/searxng/settings.yml \
-    UWSGI_SETTINGS_PATH=/etc/searxng/uwsgi.ini
+    UWSGI_SETTINGS_PATH=/etc/searxng/uwsgi.ini \
+    UWSGI_WORKERS=%k \
+    UWSGI_THREADS=4
 
 WORKDIR /usr/local/searxng
 
diff --git a/dockerfiles/uwsgi.ini b/dockerfiles/uwsgi.ini
index 2d3155976..fc026b792 100644
--- a/dockerfiles/uwsgi.ini
+++ b/dockerfiles/uwsgi.ini
@@ -4,8 +4,12 @@ uid = searxng
 gid = searxng
 
 # Number of workers (usually CPU count)
-workers = %k
-threads = 4
+# default value: %k (= number of CPU core, see Dockerfile)
+workers = $(UWSGI_WORKERS)
+
+# Number of threads per worker
+# default value: 4 (see Dockerfile)
+threads = $(UWSGI_THREADS)
 
 # The right granted on the created socket
 chmod-socket = 666
diff --git a/docs/admin/installation-docker.rst b/docs/admin/installation-docker.rst
index c667c4f44..09471891b 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
diff --git a/utils/searxng.sh b/utils/searxng.sh
index e04f87e10..197188a4a 100755
--- a/utils/searxng.sh
+++ b/utils/searxng.sh
@@ -177,6 +177,7 @@ main() {
 
     case $1 in
         --getenv)  var="$2"; echo "${!var}"; exit 0;;
+        --cmd)  shift; "$@";;
         -h|--help) usage; exit 0;;
         install)
             sudo_or_exit
diff --git a/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini b/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini
index 351965a1e..650c8cc3f 100644
--- a/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini
+++ b/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini
@@ -47,6 +47,9 @@ plugin = python
 # default behaviour is for performance reasons.
 enable-threads = true
 
+# Number of workers (usually CPU count)
+workers = ${UWSGI_WORKERS:-%k}
+threads = ${UWSGI_THREADS:-4}
 
 # plugin: python
 # --------------
diff --git a/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini:socket b/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini:socket
index 0f36e4178..eb1220233 100644
--- a/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini:socket
+++ b/utils/templates/etc/uwsgi/apps-archlinux/searxng.ini:socket
@@ -47,6 +47,9 @@ plugin = python
 # default behaviour is for performance reasons.
 enable-threads = true
 
+# Number of workers (usually CPU count)
+workers = ${UWSGI_WORKERS:-%k}
+threads = ${UWSGI_THREADS:-4}
 
 # plugin: python
 # --------------
diff --git a/utils/templates/etc/uwsgi/apps-available/searxng.ini b/utils/templates/etc/uwsgi/apps-available/searxng.ini
index caefdf0bb..7d367d9ee 100644
--- a/utils/templates/etc/uwsgi/apps-available/searxng.ini
+++ b/utils/templates/etc/uwsgi/apps-available/searxng.ini
@@ -50,6 +50,9 @@ plugin = python3,http
 # default behaviour is for performance reasons.
 enable-threads = true
 
+# Number of workers (usually CPU count)
+workers = ${UWSGI_WORKERS:-%k}
+threads = ${UWSGI_THREADS:-4}
 
 # plugin: python
 # --------------
diff --git a/utils/templates/etc/uwsgi/apps-available/searxng.ini:socket b/utils/templates/etc/uwsgi/apps-available/searxng.ini:socket
index 516787be1..2f95fab7c 100644
--- a/utils/templates/etc/uwsgi/apps-available/searxng.ini:socket
+++ b/utils/templates/etc/uwsgi/apps-available/searxng.ini:socket
@@ -50,6 +50,9 @@ plugin = python3,http
 # default behaviour is for performance reasons.
 enable-threads = true
 
+# Number of workers (usually CPU count)
+workers = ${UWSGI_WORKERS:-%k}
+threads = ${UWSGI_THREADS:-4}
 
 # plugin: python
 # --------------