Add support for storing state in Redis

docs/config.rst

@@ -340,6 +340,7 @@ Enables persistent mode in Flower.
 When persistent mode is enabled, Flower saves its current state and reloads it upon restart.
 This ensures that Flower retains its state and configuration across restarts.
 Flower stores its state in a database file specified by the `db`_ option.
+If `db` starts with `redis://`, Flower will use Redis as a backend for storing its state.
 
 .. _port:
 

flower/events.py

@@ -1,5 +1,6 @@
 import collections
 import logging
+import pickle
 import shelve
 import threading
 import time
@@ -13,6 +14,11 @@
 from tornado.ioloop import PeriodicCallback
 from tornado.options import options
 
+try:
+    import redis
+except ImportError:
+    redis = None
+
 logger = logging.getLogger(__name__)
 
 PROMETHEUS_METRICS = None
@@ -125,21 +131,33 @@ def __init__(self, capp, io_loop, db=None, persistent=False,
 
         self.db = db
         self.persistent = persistent
+        self.redis_client = None
+        if self.persistent and self.db.startswith("redis://"):
+            if not redis:
+                raise ImportError('redis library is required')
+            self.redis_client = redis.Redis.from_url(self.db)
         self.enable_events = enable_events
         self.state = None
         self.state_save_timer = None
 
         if self.persistent:
-            logger.debug("Loading state from '%s'...", self.db)
-            state = shelve.open(self.db)
-            if state:
-                self.state = state['events']
-            state.close()
-
             if state_save_interval:
                 self.state_save_timer = PeriodicCallback(self.save_state,
                                                          state_save_interval)
 
+            if self.redis_client:
+                logger.debug("Loading state from Redis...")
+                state = self.redis_client.get('flower_events')
+                if state:
+                    self.state = pickle.loads(state)
+
+            if not self.redis_client:
+                logger.debug("Loading state from '%s'...", self.db)
+                state = shelve.open(self.db)
+                if state:
+                    self.state = state['events']
+                state.close()
+
         if not self.state:
             self.state = EventsState(**kwargs)
 
@@ -195,10 +213,14 @@ def run(self):
                 time.sleep(try_interval)
 
     def save_state(self):
-        logger.debug("Saving state to '%s'...", self.db)
-        state = shelve.open(self.db, flag='n')
-        state['events'] = self.state
-        state.close()
+        if self.redis_client:
+            logger.debug("Saving state to Redis...")
+            self.redis_client.set('flower_events', pickle.dumps(self.state))
+        else:
+            logger.debug("Saving state to '%s'...", self.db)
+            state = shelve.open(self.db, flag='n')
+            state['events'] = self.state
+            state.close()
 
     def on_enable_events(self):
         # Periodically enable events for workers