[PATCH 2 of 3] Upstream: allow recovery from "429 Too Many Requests" response

[Piotr Sikora]

Hey Maxim,

> Sure, but why one would use "proxy_next_upstream http_429" then?
>
> If one of your backends reject a requests based on client's IP /
> login, then you probably don't want nginx to retry such a request
> on other servers, as this will just allow the user to do more
> requests when you already know the limit was reached.  And it
> doesn't look like an effective way to build a system with
> distributed limits.
>
> In contrast, if a limit affects nginx's IP and/or group of
> services on a backend, retrying on a different backend may make
> sense.  But use case suggests that 429 should be counted as
> failure.

That's a good point. Fixed, thanks!

Best regards,
Piotr Sikora