[mod] migrate from Redis to Valkey (#4795)

This patch migrates from `redis==5.2.1` [1] to `valkey==6.1.0` [2].

The migration to valkey is necessary because the company behind Redis has decided
to abandon the open source license. After experiencing a drop in user numbers,
they now want to run it under a dual license again. But this move demonstrates
once again how unreliable the company is and how it treats open source
developers.

To review first, read the docs::

    $ make docs.live

Follow the instructions to remove redis:

- http://0.0.0.0:8000/admin/settings/settings_redis.html

Config and install a local valkey DB:

- http://0.0.0.0:8000/admin/settings/settings_valkey.html

[1] https://pypi.org/project/redis/
[2] https://pypi.org/project/valkey/

Co-authored-by: HLFH <gaspard@dhautefeuille.eu>
Co-authored-by: Markus Heiser <markus.heiser@darmarit.de>

4 files changed, 71 insertions, 31 deletions

diff --git a/docs/admin/settings/index.rst b/docs/admin/settings/index.rst
index eb0e07a53..b9d0408ea 100644
--- a/docs/admin/settings/index.rst
+++ b/docs/admin/settings/index.rst
@@ -20,8 +20,7 @@ Settings
    settings_server
    settings_ui
    settings_redis
+   settings_valkey
    settings_outgoing
    settings_categories_as_tabs
    settings_plugins
-
-
diff --git a/docs/admin/settings/settings_redis.rst b/docs/admin/settings/settings_redis.rst
index 9fb067553..e1221ac32 100644
--- a/docs/admin/settings/settings_redis.rst
+++ b/docs/admin/settings/settings_redis.rst
@@ -4,46 +4,34 @@
 ``redis:``
 ==========
 
-.. _Redis.from_url(url): https://redis-py.readthedocs.io/en/stable/connections.html#redis.client.Redis.from_url
+.. _Valkey: https://valkey.io
 
-A redis DB can be connected by an URL, in :py:obj:`searx.redisdb` you
-will find a description to test your redis connection in SearXNG.  When using
-sockets, don't forget to check the access rights on the socket::
+.. attention::
 
-  ls -la /usr/local/searxng-redis/run/redis.sock
-  srwxrwx--- 1 searxng-redis searxng-redis ... /usr/local/searxng-redis/run/redis.sock
+   SearXNG is switching from the Redis DB to Valkey_. The configuration
+   description of Valkey_ in SearXNG can be found here: :ref:`settings
+   <settings valkey>`.
 
-In this example read/write access is given to the *searxng-redis* group.  To get
-access rights to redis instance (the socket), your SearXNG (or even your
-developer) account needs to be added to the *searxng-redis* group.
-
-``url`` : ``$SEARXNG_REDIS_URL``
-  URL to connect redis database, see `Redis.from_url(url)`_ & :ref:`redis db`::
-
-    redis://[[username]:[password]]@localhost:6379/0
-    rediss://[[username]:[password]]@localhost:6379/0
-    unix://[[username]:[password]]@/path/to/socket.sock?db=0
+If you have built and installed a local Redis DB for SearXNG, it is recommended
+to uninstall it now and replace it with the installation of a Valkey_ DB.
 
 .. _Redis Developer Notes:
 
 Redis Developer Notes
 =====================
 
-To set up a local redis instance, first set the socket path of the Redis DB
-in your YAML setting:
+To uninstall SearXNG's local Redis DB you can use:
 
-.. code:: yaml
+.. code:: sh
 
-   redis:
-     url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
+   # stop your SearXNG instance
+   $ ./utils/searxng.sh remove.redis
 
-Then use the following commands to install the redis instance (:ref:`manage
-redis.help`):
+Remove the Redis DB in your YAML setting:
 
-.. code:: sh
+.. code:: yaml
 
-   $ ./manage redis.build
-   $ sudo -H ./manage redis.install
-   $ sudo -H ./manage redis.addgrp "${USER}"
-   # don't forget to logout & login to get member of group
+   redis:
+     url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
 
+To install Valkey_ read: :ref:`Valkey Developer Notes`
diff --git a/docs/admin/settings/settings_server.rst b/docs/admin/settings/settings_server.rst
index 84908d43f..59c0d7791 100644
--- a/docs/admin/settings/settings_server.rst
+++ b/docs/admin/settings/settings_server.rst
@@ -36,7 +36,7 @@
 
 ``limiter`` :  ``$SEARXNG_LIMITER``
   Rate limit the number of request on the instance, block some bots.  The
-  :ref:`limiter` requires a :ref:`settings redis` database.
+  :ref:`limiter` requires a :ref:`settings valkey` database.
 
 .. _public_instance:
 
diff --git a/docs/admin/settings/settings_valkey.rst b/docs/admin/settings/settings_valkey.rst
new file mode 100644
index 000000000..396d5c8ad
--- /dev/null
+++ b/docs/admin/settings/settings_valkey.rst
@@ -0,0 +1,53 @@
+.. _settings valkey:
+
+===========
+``valkey:``
+===========
+
+.. _Valkey:
+    https://valkey.io
+.. _Valkey-Installation:
+    https://valkey.io/topics/installation/
+.. _There are several ways to specify a database number:
+    https://valkey-py.readthedocs.io/en/stable/connections.html#valkey.Valkey.from_url
+
+A Valkey_ DB can be connected by an URL, in section :ref:`valkey db` you will
+find a description to test your valkey connection in SearXNG.
+
+``url`` : ``$SEARXNG_VALKEY_URL``
+  URL to connect valkey database. `There are several ways to specify a database
+  number`_::
+
+    valkey://[[username]:[password]]@localhost:6379/0
+    valkeys://[[username]:[password]]@localhost:6379/0
+    unix://[[username]:[password]]@/path/to/socket.sock?db=0
+
+  When using sockets, don't forget to check the access rights on the socket::
+
+    ls -la /usr/local/searxng-valkey/run/valkey.sock
+    srwxrwx--- 1 searxng-valkey searxng-valkey ... /usr/local/searxng-valkey/run/valkey.sock
+
+  In this example read/write access is given to the *searxng-valkey* group.  To
+  get access rights to valkey instance (the socket), your SearXNG (or even your
+  developer) account needs to be added to the *searxng-valkey* group.
+
+
+.. _Valkey Developer Notes:
+
+Valkey Developer Notes
+======================
+
+To set up a local Valkey_ DB, set the URL connector in your YAML setting:
+
+.. code:: yaml
+
+   valkey:
+     url: valkey://localhost:6379/0
+
+To install a local Valkey_ DB from package manager read `Valkey-Installation`_
+or use:
+
+.. code:: sh
+
+   $ ./utils/searxng.sh install valkey
+   # restart your SearXNG instance