A task to keep track of the various 429 rate limiting issues due to the thumbnail requests failing. These 429s are different from 429s that are cause by the amount of requests made by the user (which can cause things like T266155)

These 429s due to problems with the thumbnail requests are expected (for multiples reasons), but the presence of the 429 tends to obfuscates the root cause, making it confusing. Two of these reasons are:

• failure throttling https://wikitech.wikimedia.org/wiki/Thumbor#Failure Here the file might have a problem that makes it impossible to generate a thumbnail. The original might be broken, or it takes too long to make a thumbnail for this original
• 'Expensive' file throttling https://wikitech.wikimedia.org/wiki/Thumbor#Expensive The file is overly expensive to deal with compared to normal traffic.

Because these errors can happen for so many different reasons, it can be difficult to debug them and some simply cannot be solved without major rearchitecting of infrastructure layers. This ticket makes it easier to keep these various causes findable.