Add threaded download monitoring with Prometheus metrics

modules/download_monitor.py

@@ -0,0 +1,56 @@
+import logging
+import threading
+import time
+
+from pytubefix import YouTube
+from modules.metrics import MetricsHandler
+
+
+TEST_VIDEO_URL = "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
+
+
+def monitor_download():
+    start = time.time()
+
+    try:
+        video = YouTube(TEST_VIDEO_URL)
+
+        stream = (
+            video.streams.filter(
+                resolution="360p",
+                progressive=True,
+            )
+            .order_by("resolution")
+            .desc()
+            .first()
+        )
+
+        if stream is None:
+            raise Exception("No suitable stream found")
+
+        stream.download(
+            output_path="/dev",
+            filename="null",
+        )
+
+        duration = time.time() - start
+
+        MetricsHandler.download_monitor_success.set(1)
+        MetricsHandler.download_monitor_duration_seconds.set(duration)
+
+        logging.info(f"Download monitoring succeeded in {duration:.2f} seconds")
+
+    except Exception as e:
+        MetricsHandler.download_monitor_success.set(0)
+        MetricsHandler.download_monitor_failures_total.inc()
+        logging.exception(f"Download monitoring failed: {e}")
+
+
+def start_download_monitor(interval: int):
+    def monitor_loop():
+        while True:
+            monitor_download()
+            time.sleep(interval)
+
+    thread = threading.Thread(target=monitor_loop, daemon=True)
+    thread.start()

server.py

@@ -29,6 +29,7 @@
 from modules.args import get_args
 from modules.cache import Cache
 from modules.metrics import MetricsHandler
+from modules.download_monitor import start_download_monitor
 
 
 logging.Formatter.converter = time.gmtime
@@ -798,7 +799,13 @@ def startup():
     threading.Thread(target=download_video_worker, daemon=True).start()
     threading.Thread(target=play_video_worker, daemon=True).start()
 
+    if args.download_monitoring_interval > 0:
+        start_download_monitor(args.download_monitoring_interval)
 
+        logging.info(
+            f"Started download monitoring every {args.download_monitoring_interval} seconds"
+        )
+
 @app.get("/announcement")
 async def announcement():
     return FileResponse("static/announcement.html")