gistfile1.txt

backend cache {
    .host = "s3bucket";
}

backend tilestash {
    .host = "tilestashhost";
    .port = "8000";
}

sub vcl_recv {
    if (req.restarts == 0) {
        set req.backend = default;
    } else {            
        set req.backend = backup;
    }
}

sub vcl_fetch {
    if (beresp.status == 404) {
        return (restart);
    }
}