Site Monitoring: Clarify Rate Limits for 429 Errors

[Aurorum]

I was slightly taken aback by how many "429 Too Many Requests" errors there were for HTTP requests to my WordPress.com site.

I have two questions:

1. What actually is the rate limit?
2. If there exists a high proportion of those errors, would it be worth clarifying in Calypso what those limits are? At the moment, I get the impression that Calypso is telling me that there are errors, but not why there are or what I can do about them.

cc @sejas @katinthehatsite @danielbachhuber - sorry, I've no idea whom to ping for this but it looks like you all worked on Site Monitoring, so hope you won't mind me asking you! Thanks very much! :)

[sejas]

@Aurorum , I indeed worked in the Site Monitoring feature. I checked the documentation https://developer.wordpress.com/docs/troubleshooting/site-monitoring/#unsuccessful-http-responses , and I couldn't find any description about the 429 HTTP errors.

AFAIK, we don't limit in the number of requests 🤔. We have a limited number of CPU workers assigned per site allowing a temporal boost. I'll ask internally and come back with a second answer.

If there exists a high proportion of those errors, would it be worth clarifying in Calypso what those limits are? At the moment, I get the impression that Calypso is telling me that there are errors, but not why there are or what I can do about them.

This is great feedback. When developing the Site Monitoring we discussed it how to make these charts more understandable.

Open source is super cool 🙌 , isn't it?

[Aurorum]

Thanks for taking a look @sejas!

AFAIK, we don't limit in the number of requests 🤔. We have a limited number of CPU workers assigned per site allowing a temporal boost. I'll ask internally and come back with a second answer.

Ah, that's interesting - I'm very curious on what that limited number might be though and whether that's triggering the 429 errors, so would definitely love to hear the second answer! It's just surprised me how frequent those errors are.

Open source is super cool 🙌 , isn't it?

It is indeed! By the way, since I didn't mention it, just wanted to put on record that the Site Monitoring feature is super awesome. :) Other than this small hiccup, I've found the charts very clear and useful.

[sejas]

Hi @Aurorum,
Some reasons that can lead to a 429 response can be a rate limiting from different traffic sources, DDoS protection measures, and a lack of available PHP workers, among others.

If your site is serving GET requests, they probably are cached and not consuming any PHP worker.
If you have forms, or any other Ajax call it's safer to add some security measures like captchas, nonces to avoid bots from exploiting them.

Do you have any other question?