Unable to set Retry-After header with 503 response

[phillipoldham.myopenid.com]

Currently its not possible to use add_header to set a Retry-After header when responding with a 503 header. This causes a problems when trying to inform clients to retry after a timeout when to bring backends back-up after an error.

There are currently work-arounds which involve issuing the headers via a dynamic language (either with a proxy or the perl module) however this may not be possible if these are the cause of the 503.

Suggested resolutions:
Either allow "add_headers retry-after" for 50x errors, or change the syntax of error_page to allow one to append "retry-after x" to the entry and have nginx add the header.

[Sergey Kandaurov <pluknet@…>]

In 74ffe03555d002388159365afddc0cbe4967c35c/nginx:

Headers filter: "add_header" with "always" parameter (ticket #98).

If specified, the header field is set regardless of the status code.