fix: Improve Docker container shutdown handling

- Add proper signal handlers for graceful shutdown of all components
- Implement WebhookBatcher.shutdown() to properly close ThreadPoolExecutor and cancel timers
- Add NFOGuardDatabase.close() method to close thread-local database connections
- Increase uvicorn graceful shutdown timeout to 15 seconds
- Add cleanup in finally block to ensure resources are freed even if signal handler fails
- Reduce logging and server header overhead for better performance

This should resolve Docker container shutdown issues where containers don't respond to SIGTERM properly.

Bump version to 2.1.1

🤖 Generated with [Claude Code](https://claude.ai/code)

main.py

@@ -114,6 +114,28 @@ def initialize_components():
 def signal_handler(signum, frame):
     """Handle shutdown signals gracefully"""
     _log("INFO", f"Received signal {signum}, shutting down gracefully...")
+    
+    # Get the global dependencies if they exist
+    if hasattr(signal_handler, 'dependencies') and signal_handler.dependencies:
+        deps = signal_handler.dependencies
+        
+        # Shutdown webhook batcher cleanly
+        if 'batcher' in deps:
+            try:
+                _log("INFO", "Shutting down webhook batcher...")
+                deps['batcher'].shutdown()
+            except Exception as e:
+                _log("WARNING", f"Error during batcher shutdown: {e}")
+        
+        # Close database connection
+        if 'db' in deps:
+            try:
+                _log("INFO", "Closing database connection...")
+                deps['db'].close()
+            except Exception as e:
+                _log("WARNING", f"Error closing database: {e}")
+    
+    _log("INFO", "Graceful shutdown complete")
     sys.exit(0)
 
 
@@ -139,6 +161,9 @@ def main():
     # Initialize components
     dependencies = initialize_components()
     
+    # Store dependencies globally for signal handler access
+    signal_handler.dependencies = dependencies
+    
     # Register routes
     register_routes(app, dependencies)
     
@@ -147,13 +172,32 @@ def main():
             app,
             host="0.0.0.0", 
             port=int(os.environ.get("PORT", "8080")),
-            reload=False
+            reload=False,
+            access_log=False,  # Reduce logging overhead
+            server_header=False,  # Reduce response overhead
+            timeout_graceful_shutdown=15  # Give more time for graceful shutdown
         )
     except KeyboardInterrupt:
         _log("INFO", "NFOGuard stopped by user")
     except Exception as e:
         _log("ERROR", f"NFOGuard crashed: {e}")
         sys.exit(1)
+    finally:
+        # Ensure cleanup happens even if uvicorn doesn't trigger signal handler
+        if hasattr(signal_handler, 'dependencies') and signal_handler.dependencies:
+            deps = signal_handler.dependencies
+            
+            if 'batcher' in deps:
+                try:
+                    deps['batcher'].shutdown()
+                except Exception:
+                    pass
+            
+            if 'db' in deps:
+                try:
+                    deps['db'].close()
+                except Exception:
+                    pass
 
 
 if __name__ == "__main__":