Implement the x-accel header by Ngnix in Varnish

varnishtest "implementing x-accel-redirect"

server s1 {
        rxreq
        expect req.url == "/s1"
        txresp -hdr "X-Accel-Redirect: /s2"
        rxreq
        expect req.url == "/s2"
        txresp
} -start

varnish v1 -vcl+backend {
        sub vcl_deliver {
                if (resp.http.X-Accel-Redirect) {
                        set req.url = resp.http.X-Accel-Redirect;
                        return (restart);
                }
        set resp.http.X-url = req.url;
        }
} -start

client c1 {
        txreq -url "/s1"
        rxresp
        expect resp.http.X-url == "/s2"
} -run