Envoy: Custom error html page

[feature-id]

Hi.

Is it possible to replace 50X status replies with some custom html page + 200 OK, like nginx or haproxy do with error_page directive? (they use internal redirect for that, afaiu)

Did some search and found that https://github.com/envoyproxy/envoy/pull/11007 is already merged, but looks like this is for local pages only and not for html?

[mattklein123]

I will mark this help wanted. I think this is a fairly simple change to allow the content-type to be set as part of the reply mapper. @qiwzhang wdyt?

[feature-id]

I'd agree even with the option to leave content-type not touched by envoy, if that makes sense (in our case backend sets this header).
Is it possible to get this feature in 1.15.0 release?

[SolovyevAndrei]

Hello

We need such feature too. Want to show beatiful error page to customers, when something is wrong with our backends.
It was quite easy with error_page in nginx. But no such possibility in envoy.

[deveshkandpal24121990]

@mattklein123 - I would like to work on this issue. Can you please assign this to me ?

[dio]

@mattklein123 for modifying proxied response (with non-2xx status), do you think it makes sense to have an error_page filter? (or to extend the local reply to work in response path; in Nginx, we need to turn on proxy_intercept_errors to let non-2xx proxied response to be handled by the proxy's error_page config).

I can see it can also be implemented in Lua (with some thinking on how to not complicate the "state management" there).

[mattklein123]

@mattklein123 for modifying proxied response (with non-2xx status), do you think it makes sense to have an error_page filter? (or to extend the local reply to work in response path; in Nginx, we need to turn on proxy_intercept_errors to let non-2xx proxied response to be handled by the proxy's error_page config).

Sorry what is the use case here? To intercept upstream responses and translate them? This seems out of scope for local reply mapping?

[dio]

@mattklein123 True, sorry that I wrongly submitted the comment here 😅. Seems like I wanted to reply on this issue: https://github.com/envoyproxy/envoy/issues/12883.