feat: support redis sentinel mode (#7756)

api/extensions/ext_redis.py

@@ -1,26 +1,83 @@
 import redis
 from redis.connection import Connection, SSLConnection
+from redis.sentinel import Sentinel
 
-redis_client = redis.Redis()
+
+class RedisClientWrapper(redis.Redis):
+    """
+    A wrapper class for the Redis client that addresses the issue where the global
+    `redis_client` variable cannot be updated when a new Redis instance is returned
+    by Sentinel.
+
+    This class allows for deferred initialization of the Redis client, enabling the
+    client to be re-initialized with a new instance when necessary. This is particularly
+    useful in scenarios where the Redis instance may change dynamically, such as during
+    a failover in a Sentinel-managed Redis setup.
+
+    Attributes:
+        _client (redis.Redis): The actual Redis client instance. It remains None until
+                               initialized with the `initialize` method.
+
+    Methods:
+        initialize(client): Initializes the Redis client if it hasn't been initialized already.
+        __getattr__(item): Delegates attribute access to the Redis client, raising an error
+                           if the client is not initialized.
+    """
+
+    def __init__(self):
+        self._client = None
+
+    def initialize(self, client):
+        if self._client is None:
+            self._client = client
+
+    def __getattr__(self, item):
+        if self._client is None:
+            raise RuntimeError("Redis client is not initialized. Call init_app first.")
+        return getattr(self._client, item)
+
+
+redis_client = RedisClientWrapper()
 
 
 def init_app(app):
+    global redis_client
     connection_class = Connection
     if app.config.get("REDIS_USE_SSL"):
         connection_class = SSLConnection
 
-    redis_client.connection_pool = redis.ConnectionPool(
-        **{
-            "host": app.config.get("REDIS_HOST"),
-            "port": app.config.get("REDIS_PORT"),
-            "username": app.config.get("REDIS_USERNAME"),
-            "password": app.config.get("REDIS_PASSWORD"),
-            "db": app.config.get("REDIS_DB"),
-            "encoding": "utf-8",
-            "encoding_errors": "strict",
-            "decode_responses": False,
-        },
-        connection_class=connection_class,
-    )
+    redis_params = {
+        "username": app.config.get("REDIS_USERNAME"),
+        "password": app.config.get("REDIS_PASSWORD"),
+        "db": app.config.get("REDIS_DB"),
+        "encoding": "utf-8",
+        "encoding_errors": "strict",
+        "decode_responses": False,
+    }
+
+    if app.config.get("REDIS_USE_SENTINEL"):
+        sentinel_hosts = [
+            (node.split(":")[0], int(node.split(":")[1])) for node in app.config.get("REDIS_SENTINELS").split(",")
+        ]
+        sentinel = Sentinel(
+            sentinel_hosts,
+            sentinel_kwargs={
+                "socket_timeout": app.config.get("REDIS_SENTINEL_SOCKET_TIMEOUT", 0.1),
+                "username": app.config.get("REDIS_SENTINEL_USERNAME"),
+                "password": app.config.get("REDIS_SENTINEL_PASSWORD"),
+            },
+        )
+        master = sentinel.master_for(app.config.get("REDIS_SENTINEL_SERVICE_NAME"), **redis_params)
+        redis_client.initialize(master)
+    else:
+        redis_params.update(
+            {
+                "host": app.config.get("REDIS_HOST"),
+                "port": app.config.get("REDIS_PORT"),
+                "connection_class": connection_class,
+            }
+        )
+        pool = redis.ConnectionPool(**redis_params)
+        redis_client.initialize(redis.Redis(connection_pool=pool))
 
     app.extensions["redis"] = redis_client