I have a Google App Engine (Flexible Python) application running with Stackdriver monitoring. I have been getting failing uptime checks and I can't figure out if there is a real problem or not. The service appears to be available when I query it, and when I click the Test button in the Stackdriver uptime check, the response comes back as requested. However, according to the UI the checks seem to be failing consistently from their Virginia source but succeeding from other sources.
I can't find any corresponding errors in the server logs. I can confirm that I see other 404 errors when triggered manually.
Any ideas how to debug this, or failing that, how to at least modify my Stackdriver uptime check to exclude this (apparently false) alert?
Thanks!