Improve error reporting

server/handlers/quietstaticfilehandler.py

@@ -0,0 +1,16 @@
+import logging
+
+from tornado.web import StaticFileHandler, HTTPError
+
+
+class QuietStaticFileHandler(StaticFileHandler):
+    """Minor override of logging in StaticFileHandler to log HTTP errors at debug level instead of their usual
+    warning level. Without this, attacks on Spothole which try to do path traversal attacks would log exceptions
+    from inside Tornado, and the server logs would contain a lot of this type of content. This effectively changes
+    the log level of these exceptions to DEBUG so they are only logged if DEBUG level logging is enabled."""
+
+    def log_exception(self, typ, value, tb):
+        if isinstance(value, HTTPError):
+            logging.debug(value)
+            return
+        super().log_exception(typ, value, tb)

server/webserver.py

@@ -103,7 +103,7 @@ class WebServer:
         misc_routes = [
             (r"/apidocs", PageTemplateHandler, {"template_name": "apidocs", **handler_opts}),
             (r"/metrics", PrometheusMetricsHandler),
-            (r"/(.*)", StaticFileHandler, {"path": os.path.join(_HERE, "../webassets")})
+            (r"/(.*)", QuietStaticFileHandler, {"path": os.path.join(_HERE, "../webassets")})
         ]
 
         app = tornado.web.Application(api_routes + ui_routes + misc_routes,