Initialize Redis in searx/webapp.py

settings.yml:
* The default URL was unix:///usr/local/searxng-redis/run/redis.sock?db=0
* The default URL is now "false"

The default URL makes the log difficult to deal with:
if the admin didn't install a Redis instance, the logs record a false error.

It worked before because SearXNG initialized the Redis connection when the limiter started.

In this commit, SearXNG initializes Redis in searx/webapp.py
so various components can use Redis without taking care of the initialization step.

7 files changed, 36 insertions, 24 deletions

diff --git a/docs/admin/engines/settings.rst b/docs/admin/engines/settings.rst
index 086b3ccbe..3ac992d3e 100644
--- a/docs/admin/engines/settings.rst
+++ b/docs/admin/engines/settings.rst
@@ -314,20 +314,21 @@ developer) account needs to be added to the *searxng-redis* group.
 
 .. admonition:: Tip for developers
 
-   To set up a local redis instance using sockets simply use::
-
-     $ ./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
-
-   The YAML setting for such a redis instance is:
+   To set up a local redis instance, first set the socket path of the Redis DB
+   in your YAML setting:
 
    .. code:: yaml
 
       redis:
         url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
 
+   Then use the following commands to install the redis instance ::
+
+     $ ./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
+
 
 .. _settings outgoing:
 
diff --git a/searx/search/checker/scheduler.lua b/searx/search/checker/scheduler.lua
index b3c6023fe..c5ebb05bc 100644
--- a/searx/search/checker/scheduler.lua
+++ b/searx/search/checker/scheduler.lua
@@ -18,8 +18,8 @@ if (next_call_ts == false or next_call_ts == nil) then
     -- the scheduler has never run on this Redis instance, so:
     -- 1/ the scheduler does not run now
     -- 2/ the next call is a random time between start_after_from and start_after_to
-    local delay = start_after_from + math.random(start_after_to - start_after_from)
-    redis.call('SET', redis_key, now + delay)
+    local initial_delay = math.random(start_after_from, start_after_to)
+    redis.call('SET', redis_key, now + initial_delay)
     return { false, delay }
 end
 
@@ -30,7 +30,7 @@ local call_now = next_call_ts <= now
 if call_now then
     -- the checker runs now, define the timestamp of the next call:
     -- this is a random delay between every_from and every_to
-    local periodic_delay = every_from + math.random(every_to - every_from)
+    local periodic_delay = math.random(every_from, every_to)
     next_call_ts = redis.call('INCRBY', redis_key, periodic_delay)
 end
 return { call_now, next_call_ts - now }
diff --git a/searx/settings.yml b/searx/settings.yml
index 2304c6fe7..36ed90b22 100644
--- a/searx/settings.yml
+++ b/searx/settings.yml
@@ -78,7 +78,7 @@ server:
 
 redis:
   # https://redis-py.readthedocs.io/en/stable/connections.html#redis.client.Redis.from_url
-  url: unix:///usr/local/searxng-redis/run/redis.sock?db=0
+  url: false
 
 ui:
   # Custom static path - leave it blank if you didn't change
diff --git a/searx/settings_defaults.py b/searx/settings_defaults.py
index a4f6ce607..470290f92 100644
--- a/searx/settings_defaults.py
+++ b/searx/settings_defaults.py
@@ -174,7 +174,7 @@ SCHEMA = {
         'default_http_headers': SettingsValue(dict, {}),
     },
     'redis': {
-        'url': SettingsValue(str, 'unix:///usr/local/searxng-redis/run/redis.sock?db=0'),
+        'url': SettingsValue((None, False, str), False),
     },
     'ui': {
         'static_path': SettingsDirectoryValue(str, os.path.join(searx_dir, 'static')),
diff --git a/searx/shared/redisdb.py b/searx/shared/redisdb.py
index d0071f72c..6cc4e46d1 100644
--- a/searx/shared/redisdb.py
+++ b/searx/shared/redisdb.py
@@ -26,20 +26,31 @@ import redis
 from searx import get_setting
 
 
+OLD_REDIS_URL_DEFAULT_URL = 'unix:///usr/local/searxng-redis/run/redis.sock?db=0'
+"""This was the default Redis URL in settings.yml."""
+
+_CLIENT = None
 logger = logging.getLogger('searx.shared.redisdb')
-_client = None
 
 
 def client() -> redis.Redis:
-    return _client
+    return _CLIENT
 
 
 def initialize():
-    global _client  # pylint: disable=global-statement
+    global _CLIENT  # pylint: disable=global-statement
+    redis_url = get_setting('redis.url')
     try:
-        _client = redis.Redis.from_url(get_setting('redis.url'))
-        logger.info("connected redis: %s", get_setting('redis.url'))
-    except redis.exceptions.ConnectionError as exc:
+        if redis_url:
+            _CLIENT = redis.Redis.from_url(redis_url)
+            logger.info("connected redis: %s", redis_url)
+            return True
+    except redis.exceptions.ConnectionError:
         _pw = pwd.getpwuid(os.getuid())
-        logger.error("[%s (%s)] can't connect redis DB ...", _pw.pw_name, _pw.pw_uid)
-        logger.error("  %s", exc)
+        logger.exception("[%s (%s)] can't connect redis DB ...", _pw.pw_name, _pw.pw_uid)
+        if redis_url == OLD_REDIS_URL_DEFAULT_URL:
+            logger.info(
+                "You can safely ignore the above Redis error if you don't use Redis."
+                "You can remove this error by setting redis.url to false in your settings.yml."
+            )
+    return False
diff --git a/utils/searxng.sh b/utils/searxng.sh
index 58f220e1f..e7aa8ed15 100755
--- a/utils/searxng.sh
+++ b/utils/searxng.sh
@@ -295,7 +295,7 @@ In your instance, redis DB connector is configured at:
 
     ${redis_url}
 "
-    if searxng.instance.exec python -c "from searx.shared import redisdb; redisdb.init() or exit(42)"; then
+    if searxng.instance.exec python -c "from searx.shared import redisdb; redisdb.initialize() or exit(42)"; then
         info_msg "SearXNG instance is able to connect redis DB."
         return
     fi
@@ -684,7 +684,7 @@ To install uWSGI use::
         die 42 "SearXNG's uWSGI app not available"
     fi
 
-    if ! searxng.instance.exec python -c "from searx.shared import redisdb; redisdb.init() or exit(42)"; then
+    if ! searxng.instance.exec python -c "from searx.shared import redisdb; redisdb.initialize() or exit(42)"; then
         rst_para "\
 The configured redis DB is not available: If your server is public to the
 internet, you should setup a bot protection to block excessively bot queries.
diff --git a/utils/searxng_check.py b/utils/searxng_check.py
index 39e774340..bd2d60288 100644
--- a/utils/searxng_check.py
+++ b/utils/searxng_check.py
@@ -29,6 +29,6 @@ if os.path.isfile(OLD_SETTING):
 from searx.shared import redisdb
 from searx import get_setting
 
-if not redisdb.init():
+if not redisdb.initialize():
     warnings.warn("can't connect to redis DB at: %s" % get_setting('redis.url'), RuntimeWarning, stacklevel=2)
     warnings.warn("--> no bot protection without redis DB", RuntimeWarning, stacklevel=2)