Varnish - set backend if statuscode is 404

[Tobias Honacker]

Hi Jan,

This is my solution:

sub vcl_recv {

// Redirect 404er Pictures - vcl_fetch will restart request and set new
header to match with this rule
if (req.http.host == "new-header.de") {
       if (req.url ~ "^/var/storage/images") {
           set req.backend = new_backend;
       }
        }
}


sub vcl_fetch {

        if ((beresp.status == 404) && (req.url ~ "^/var/storage/images")) {
     set req.http.Host = "new-header.de";
     return(restart);
        }
}


You have to set a new header and restart the request thats it.


Best regards,
Tobias

Am 28.11.13 16:15 schrieb "Jan-Frode Myklebust" unter <janfrode at tanso.net>:

>If you manage to do this, I would much appreciate you post a recipie :-)
>I've been struggeling trying to achieve the same thing, without
>success..
>
>Actually my setup is a bit different, we have a director, and just want
>to check the other backend if the first backend gives 404, but the same
>solution might apply.
>
>backend backend1 {
>        .host = "backend1.example.com";
>        .probe = {
>                .url = "/alive.html";
>                .timeout = 34 ms;
>                .interval = 2s;
>                .window = 10;
>                .threshold = 8;
>        }
>}
>backend backend2 {
>        .host = "backend2.example.com";
>        .probe = {
>                .url = "/alive.html";
>                .timeout = 34 ms;
>                .interval = 2s;
>                .window = 10;
>                .threshold = 8;
>        }
>}
>director dir1 client {
>    { .backend = backend1; .weight = 1; }
>    { .backend = backend2; .weight = 1; }
>}
>sub vcl_recv {
>        if ( req.http.host ~ "(?i)www.example.com$"  ) {
>                set req.backend = dir1;
>                return(lookup);
>        }
>}
>
>
>
>  -jf