Varnish ，是什么原因造成撞球？

Question

这是varnishlog(已编辑-展开以提供更多信息):

*   << Request  >> 172651    
-   Begin          req 172650 rxreq
-   Timestamp      Start: 1455791132.581465 0.000000 0.000000
-   Timestamp      Req: 1455791132.581465 0.000000 0.000000
-   ReqStart       127.0.0.1 47991
-   ReqMethod      GET
-   ReqURL         /
-   ReqProtocol    HTTP/1.1
-   ReqHeader      X-Real-IP: x.x.x.x
-   ReqHeader      X-Forwarded-For: x.x.x.1, x.x.x.2
-   ReqHeader      X-Forwarded-Proto: https
-   ReqHeader      X-Forwarded-Port: 443
-   ReqHeader      Host: mydomain.com
-   ReqHeader      User-Agent: Go-http-client/1.1  (//benchmark app, but regular browser client happens the same
-   ReqHeader      Cf-Connecting-Ip: x.x.x.x
-   ReqHeader      Cf-Ipcountry: AND
-   ReqHeader      Cf-Origin-Https: off
-   ReqHeader      Cf-Ray: 27690752ab232e21-NRT
-   ReqHeader      Cf-Visitor: {"scheme":"https"}
-   ReqUnset       X-Forwarded-For: x.x.x.1, x.x.x.2
-   ReqHeader      X-Forwarded-For: x.x.x.ext, x.x.x.1, x.x.x.2
-   VCL_call       RECV
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   Debug          "XXXX HIT-FOR-PASS"
-   HitPass        393349
-   VCL_call       PASS
-   VCL_return     fetch
-   Link           bereq 172652 pass
-   Timestamp      Fetch: 1455791132.581733 0.000268 0.000268
-   RespProtocol   HTTP/1.1
-   RespStatus     200
-   RespReason     OK
-   RespHeader     Server: nginx
-   RespHeader     Date: Thu, 18 Feb 2016 10:25:32 GMT
-   RespHeader     Content-Type: text/html; charset=utf-8
-   RespHeader     Vary: Accept-Encoding, Accept-Encoding
-   RespHeader     Etag: "1455788472-0"
-   RespHeader     Content-Language: ja
-   RespHeader     Cache-Control: no-cache
-   RespHeader     Last-Modified: Thu, 18 Feb 2016 09:41:12 GMT
-   RespHeader     X-Content-Options: nosniff
-   RespHeader     X-Micro-Cache: HIT
-   RespHeader     X-Varnish: 172651
-   RespHeader     Age: 0
-   RespHeader     Via: 1.1 varnish-v4
-   VCL_call       DELIVER
-   VCL_return     deliver
-   Timestamp      Process: 1455791132.581744 0.000279 0.000011
-   RespHeader     Accept-Ranges: bytes
-   RespHeader     Transfer-Encoding: chunked
-   Debug          "RES_MODE 8"
-   RespHeader     Connection: keep-alive
-   Timestamp      Resp: 1455791132.581794 0.000329 0.000049
-   ReqAcct        336 0 336 436 57069 57505
-   End            

我已经读到，这是在设置set-cookie header 或设置cache-control:max-age = 0时创建的。

好吧，我在我的子vcl_backend_response中有此操作，试图避免命中率。这很不礼貌，但是我不知道后端是什么原因导致此命中率的:

sub vcl_backend_response {
  unset beresp.http.set-cookie;
  unset beresp.http.expires;
  set beresp.http.Cache-Control = "max-age=6000";
}

我摆脱了Expire，因为它已设置为时间戳0。所以我可能是这样。然后，我尝试使用Cache-control，但相同。我将以这种速率取消设置所有 header ...

毕竟是304响应，为什么不缓存呢？

更多信息:后端是Drupal应用程序。

编辑1:关于vcl_recv

是的，我确实有东西，我正在返回某些路径的通行证(不是我正在检查的路径)，我正在为文件取消设置cookie，并且我正在为其余部分取消所有非drupal session 的cookie。它等于或小于复制/粘贴drupal默认子vcl_recv。如果您愿意，我可以在这里复制。

顺便说一句，我更改了其他内容，现在我在响应200中也被击中通过(但是当我使用基准测试工具时)。有人删除了说可能是由于响应304的答案。我正在检查，但答案不见了:(

好了，这里是vcl_recv:

sub vcl_recv {
 if (req.url ~ "^/status\.php$" ||
    req.url ~ "^/admin/.*$" ||
     [...]
     req.url ~ "^.*\.js.*$" ) 
    {
       return (pass);
    }

  if (req.url ~ "^/admin/content/backup_migrate/export") {
    return (pipe);
  }

  ## COOKIES ##
  if (req.url ~ "(?i)\.(css|js|jpg|jpeg|gif|png|ico|svg|map)(\?.*)?$") {
    unset req.http.Cookie;
  }
  if (req.http.Cookie) {
    set req.http.Cookie = ";" + req.http.Cookie;
    set req.http.Cookie = regsuball(req.http.Cookie, "; +", ";"); 
    set req.http.Cookie = regsuball(req.http.Cookie, ";(SESS[a-z0-9]+|SSESS[a-z0-9]+|NO_CACHE)=", "; \1=");
    set req.http.Cookie = regsuball(req.http.Cookie, ";[^ ][^;]*", "");
    set req.http.Cookie = regsuball(req.http.Cookie, "^[; ]+|[; ]+$", "");
   if (req.http.Cookie == "") {
        unset req.http.Cookie;
    }
    # if any of our cookies of interest are still there, we disable caching and pass the request
    else {
        return (pass);
    }
 }
}

它几乎总是在所有http中获得通过。 304个响应和200个响应。我已经编辑了上面的varnishlog，以显示一个完整的示例以提供更多信息。

编辑:
因此，这是请求的日志，其中显示了通过命中率。肯定是将命中率设为通行证的一种:

-   ReqHeader      X-Forwarded-For: 127.0.0.1
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   VCL_call       MISS
-   VCL_return     fetch
-   Link           bereq 3 fetch
-   Timestamp      Fetch: 1456731597.992472 0.099948 0.099948
-   RespProtocol   HTTP/1.1
-   RespStatus     200
-   RespReason     OK
-   RespHeader     Date: Mon, 29 Feb 2016 07:39:57 GMT
-   RespHeader     Content-Type: text/html; charset=utf-8
-   RespHeader     Content-Encoding: gzip
-   RespHeader     Vary: Accept-Encoding
-   RespHeader     Etag: "1456730796-0"
-   RespHeader     Content-Language: ja
-   RespHeader     Cache-Control: no-cache
-   RespHeader     Last-Modified: Mon, 29 Feb 2016 07:26:36 GMT
-   RespHeader     Expires: Thu, 01 Jan 1970 00:00:01 GMT
-   RespHeader     X-Content-Options: nosniff
-   RespHeader     X-Micro-Cache: EXPIRED
-   RespHeader     X-Varnish: 2
-   RespHeader     Age: 0
-   RespHeader     Via: 1.1 varnish-v4
-   RespUnset      Etag: "1456730796-0"
-   RespHeader     ETag: W/"1456730796-0"
-   VCL_call       DELIVER
-   RespHeader     X-Cache: MISS
-   RespHeader     X-Cache-Hits: 0
-   RespUnset      X-Varnish: 2
-   RespUnset      Via: 1.1 varnish-v4
-   VCL_return     deliver
-   Timestamp      Process: 1456731597.992517 0.099993 0.000044
-   RespUnset      Content-Encoding: gzip
-   RespHeader     Accept-Ranges: bytes
-   RespHeader     Content-Length: 53980
-   Debug          "RES_MODE 42"
-   RespHeader     Connection: keep-alive
-   Gzip           U D - 12752 53980 80 101936 101946
-   Timestamp      Resp: 1456731597.992817 0.100293 0.000300
-   ReqAcct        746 0 746 437 53980 54417

Answer 1

这个问题太长了，恐怕它对其他人也可能没有用。

感谢其他答案给出的链接，我看到了这一点(vcl_backend_response的默认实现):

sub vcl_backend_response {
if (beresp.ttl <= 0s ||
    beresp.http.Set-Cookie ||
    beresp.http.Surrogate-control ~ "no-store" ||
    (!beresp.http.Surrogate-Control &&
    beresp.http.Cache-Control ~ "no-cache|no-store|private") ||
    beresp.http.Vary == "*") {
    /*
     * Mark as "Hit-For-Pass" for the next 2 minutes
     */
    set beresp.ttl = 120s;
    set beresp.uncacheable = true;
}
return (deliver);
}

这是所有导致通过的条件。多亏了这一点，我才知道造成通行成功的原因是beresp.ttl <= 0。

那么beres.ttl是哪个值？在同一链接上，我们读到以下内容:beresp.ttl初始化为它在以下其中找到的第一个值:

The s-maxage variable in the Cache-Control response header field
The max-age variable in the Cache-Control response header field
The Expires response header field
The default_ttl parameter.

不必修改vcl_backend_response中的 header ，因为已经设置了ttl!

很好，看一下标题，我可以从后端看到:

 -  RespHeader Expires: Thu, 01 Jan 1970 00:00:01 GMT

这是导致不及格的原因。这就是我的问题的答案。现在，为什么我不知道此 header ，那将是一个不同的问题。 (我修改了nginx并使其过期30天；到所有位置都没有结果)