Add redis sentinel support (#1909)

Co-authored-by: Raphael Michel <mail@raphaelmichel.de>

doc/admin/config.rst

@@ -297,6 +297,12 @@ to speed up various operations::
     [redis]
     location=redis://127.0.0.1:6379/1
     sessions=false
+    sentinels=[
+            ["sentinel_host_1", 26379],
+            ["sentinel_host_2", 26379],
+            ["sentinel_host_3", 26379]
+        ]
+    password=password
 
 ``location``
     The location of redis, as a URL of the form ``redis://[:password]@localhost:6379/0``
@@ -305,6 +311,21 @@ to speed up various operations::
 ``session``
     When this is set to ``True``, redis will be used as the session storage.
 
+``sentinels``
+    Configures redis sentinels to use.
+    If you don't want to use redis sentinels, you should omit this option.
+    If this is set, redis via sentinels will be used instead of plain redis.
+    In this case the location should be of the form ``redis://my_master/0``.
+    The ``sentinels`` variable should be a json serialized list of sentinels,
+    each being a list with the two elements hostname and port.
+    You cannot provide a password within the location when using sentinels.
+    Note that the configuration format requires you to either place the entire
+    value on one line or make sure all values are indented by at least one space.
+
+``password``
+    If your redis setup doesn't require a password or you already specified it in the location you can omit this option.
+    If this is set it will be passed to redis as the connection option PASSWORD.
+
 If redis is not configured, pretix will store sessions and locks in the database. If memcached
 is configured, memcached will be used for caching instead of redis.
 
@@ -343,11 +364,22 @@ an AMQP server (e.g. RabbitMQ) as a broker and redis or your database as a resul
     [celery]
     broker=amqp://guest:guest@localhost:5672//
     backend=redis://localhost/0
+    broker_transport_options="{}"
+    backend_transport_options="{}"
 
 RabbitMQ might be the better choice if you have a complex, multi-server, high-performance setup,
 but as you already should have a redis instance ready for session and lock storage, we recommend
 redis for convenience. See the `Celery documentation`_ for more details.
 
+The two ``transport_options`` entries can be omitted in most cases.
+If they are present they need to be a valid JSON dictionary.
+For possible entries in that dictionary see the `Celery documentation`_.
+
+To use redis with sentinels set the broker or backend to ``sentinel://sentinel_host_1:26379;sentinal_host_2:26379/0``
+and the respective transport_options to ``{"master_name":"mymaster"}``.
+If your redis instances behind the sentinel have a password use ``sentinel://:my_password@sentinel_host_1:26379;sentinal_host_2:26379/0``.
+If your redis sentinels themselves have a password set the transport_options to ``{"master_name":"mymaster","sentinel_kwargs":{"password":"my_password"}}``.
+
 Sentry
 ------
 

src/pretix/settings.py

@@ -38,6 +38,7 @@ import logging
 import os
 import sys
 from urllib.parse import urlparse
+from json import loads
 
 import django.conf.locale
 from django.utils.crypto import get_random_string
@@ -247,23 +248,35 @@ if HAS_MEMCACHED:
     }
 
 HAS_REDIS = config.has_option('redis', 'location')
+USE_REDIS_SENTINEL = config.has_option('redis', 'sentinels')
+HAS_REDIS_PASSWORD = config.has_option('redis', 'password')
 if HAS_REDIS:
+    OPTIONS = {
+        "CLIENT_CLASS": "django_redis.client.DefaultClient",
+        "REDIS_CLIENT_KWARGS": {"health_check_interval": 30}
+    }
+
+    if USE_REDIS_SENTINEL:
+        DJANGO_REDIS_CONNECTION_FACTORY = "django_redis.pool.SentinelConnectionFactory"
+        OPTIONS["CLIENT_CLASS"] = "django_redis.client.SentinelClient"
+        OPTIONS["CONNECTION_POOL_CLASS"] = "redis.sentinel.SentinelConnectionPool"
+        # See https://github.com/jazzband/django-redis/issues/540
+        OPTIONS["SENTINEL_KWARGS"] = {"socket_timeout": 1}
+        OPTIONS["SENTINELS"] = [tuple(sentinel) for sentinel in loads(config.get('redis', 'sentinels'))]
+
+    if HAS_REDIS_PASSWORD:
+        OPTIONS["PASSWORD"] = config.get('redis', 'password')
+
     CACHES['redis'] = {
         "BACKEND": "django_redis.cache.RedisCache",
         "LOCATION": config.get('redis', 'location'),
-        "OPTIONS": {
-            "CLIENT_CLASS": "django_redis.client.DefaultClient",
-            "REDIS_CLIENT_KWARGS": {"health_check_interval": 30}
-        }
+        "OPTIONS": OPTIONS
     }
     CACHES['redis_sessions'] = {
         "BACKEND": "django_redis.cache.RedisCache",
         "LOCATION": config.get('redis', 'location'),
         "TIMEOUT": 3600 * 24 * 30,
-        "OPTIONS": {
-            "CLIENT_CLASS": "django_redis.client.DefaultClient",
-            "REDIS_CLIENT_KWARGS": {"health_check_interval": 30}
-        }
+        "OPTIONS": OPTIONS
     }
     if not HAS_MEMCACHED:
         CACHES['default'] = CACHES['redis']
@@ -279,9 +292,15 @@ if not SESSION_ENGINE:
         SESSION_ENGINE = "django.contrib.sessions.backends.db"
 
 HAS_CELERY = config.has_option('celery', 'broker')
+HAS_CELERY_BROKER_TRANSPORT_OPTS = config.has_option('celery', 'broker_transport_options')
+HAS_CELERY_BACKEND_TRANSPORT_OPTS = config.has_option('celery', 'backend_transport_options')
 if HAS_CELERY:
     CELERY_BROKER_URL = config.get('celery', 'broker')
     CELERY_RESULT_BACKEND = config.get('celery', 'backend')
+    if HAS_CELERY_BROKER_TRANSPORT_OPTS:
+        CELERY_BROKER_TRANSPORT_OPTIONS = loads(config.get('celery', 'broker_transport_options'))
+    if HAS_CELERY_BACKEND_TRANSPORT_OPTS:
+        CELERY_RESULT_BACKEND_TRANSPORT_OPTIONS = loads(config.get('celery', 'backend_transport_options'))
 else:
     CELERY_TASK_ALWAYS_EAGER = True
 

src/setup.py

@@ -186,7 +186,7 @@ setup(
         'django-oauth-toolkit==1.2.*',
         'django-otp==0.7.*,>=0.7.5',
         'django-phonenumber-field==4.0.*',
-        'django-redis==4.11.*',
+        'django-redis==5.0.*',
         'django-scopes==1.2.*',
         'django-statici18n==1.9.*',
         'djangorestframework==3.12.*',