Varnish：缓存 OPTIONS/CORS 请求

Question

如documentation中所述，哈希键是根据请求的Host标头或IP和URL计算的：

sub vcl_hash {
    hash_data(req.url);
    if (req.http.host) {
        hash_data(req.http.host);
    } else {
        hash_data(server.ip);
    }
    return (lookup);
}

HTTP OPTIONS 的正确缓存配置看起来如何，显然与相应的 HTTP GET 请求具有相同的 URL、Host 或 IP？

curl -H "Origin: https://www.example.com" -I \
  -H "Access-Control-Request-Method: GET" \
  -X OPTIONS --verbose \
  https://backend.server.example/rest/endpoint

另外，最好缓存与 Origin 标头有关的响应，该标头也是 CORS 请求的一部分。

Answer 1

试试下面的。

为了确保OPTIONS 请求方法可以被缓存，您需要从您的vcl_recv 过程中调用return 语句，这样built-in VCL 的vcl_recv 根本不会运行。并对其进行一些更改：

sub vcl_recv {
    if (req.method == "PRI") {
    /* We do not support SPDY or HTTP/2.0 */
    return (synth(405));
    }
    if (req.method != "GET" &&
      req.method != "HEAD" &&
      req.method != "PUT" &&
      req.method != "POST" &&
      req.method != "TRACE" &&
      req.method != "DELETE") {
        /* Non-RFC2616 or CONNECT which is weird. */
        return (pipe);
    }

    if (req.method != "GET" && req.method != "HEAD" && req.method != "OPTIONS") {
        /* We only deal with GET and HEAD by default */
        return (pass);
    }
    if (req.http.Authorization || req.http.Cookie) {
        /* Not cacheable by default */
        return (pass);
    }
    if (req.method == "GET" || req.method == "HEAD" || req.method == "OPTIONS") {
        set req.http.x-method = req.method;
    }
    return (hash);
}
sub vcl_backend_fetch {
    set bereq.method = bereq.http.x-method;
}

为了使缓存根据 Origin 标头值不同，您将输入如下内容：

sub vcl_hash {

    if (req.http.Origin) {
        hash_data(req.http.Origin);
    } 
    # no return here in order to have built-in.vcl do its default behavior of also caching host, URL, etc.
}