清漆升级后HTML/JSON接受不工作

Question

升级后的清漆4 ->清漆-6.2.1“接受”-Request不响应预期。

如果我使用"Accept: application/json“发出第一个请求，它将返回HTML，在第二个请求时，它将继续工作。

使用Varnish3，下面的代码片段使其工作--但与varnish6无关

sub vcl_backend_response {
    # Called after the response headers has been successfully retrieved from the backend.

    if (!beresp.http.Vary) { # no Vary at all
        set beresp.http.Vary = "Accept";
    } elseif (beresp.http.Vary !~ "Accept") { # add to existing Vary
        set beresp.http.Vary = beresp.http.Vary + ", Accept";
    }
}

sub normalize {
    # Normalize the header, remove the port (in case you're testing this on various TCP ports)
    set req.http.Host = regsub(req.http.Host, ":[0-9]+", "");
    # Remove the proxy header (see https://httpoxy.org/#mitigate-varnish)
    unset req.http.proxy;
    # Normalize the query arguments
    set req.url = std.querysort(req.url);

    if (req.http.Accept) {
        if (req.http.Accept ~ "application/json") {
            set req.http.Accept = "application/json";
        } else {
            set req.http.Accept = "text/html";
        }
    }
}

它与Varnish 3: Accept JSON returns HTML不一样，但非常相似：

Answer 1

我已经测试过您的VCL代码，它运行得很好。使sub normalize工作所需的惟一添加是以下内容：

sub vcl_recv {
    call normalize;
}

PHP测试脚本

我编写了一个小测试脚本来复制原点的变异行为。下面是代码：

<?php
header('Cache-Control: public, s-maxage=3600');
$timestamp = date('Y-m-d H:i:s');
if(isset($_SERVER['HTTP_ACCEPT']) && preg_match('/application\/json/',$_SERVER['HTTP_ACCEPT'])) {
    header('Content-Type: application/json');
    $obj = new stdClass;
    $obj->timestamp = $timestamp;
    echo json_encode($obj);
} else {
    echo $timestamp;
}

如果在application/json头中找到Accept，它将返回以下输出：

{"timestamp":"2021-11-24 07:38:35"}

否则，它将返回以下普通输出：

2021-11-24 07:38:35

VCL

下面是我为此使用的VCL：

vcl 4.1;

import std;

backend default {
    .host = "localhost";
    .port = "8080";
}

sub vcl_backend_response {
    # Called after the response headers has been successfully retrieved from the backend.

    if (!beresp.http.Vary) { # no Vary at all
        set beresp.http.Vary = "Accept";
    } elseif (beresp.http.Vary !~ "Accept") { # add to existing Vary
        set beresp.http.Vary = beresp.http.Vary + ", Accept";
    }
}

sub normalize {
    # Normalize the header, remove the port (in case you're testing this on various TCP ports)
    set req.http.Host = regsub(req.http.Host, ":[0-9]+", "");
    # Remove the proxy header (see https://httpoxy.org/#mitigate-varnish)
    unset req.http.proxy;
    # Normalize the query arguments
    set req.url = std.querysort(req.url);

    if (req.http.Accept) {
        if (req.http.Accept ~ "application/json") {
            set req.http.Accept = "application/json";
        } else {
            set req.http.Accept = "text/html";
        }
    }
}

sub vcl_recv {
    call normalize;
}

如果这不适用于您，如何调试？

您可以运行以下varnishlog命令来查看发生了什么：

varnishlog -g request -I ReqHeader:Accept -i requrl -i berequrl -I RespHeader:Vary -I BereqHeader:Accept -I BerespHeader:Vary -i vcl_call -i vcl_return

以下是HTML上现金丢失的一些示例varnishlog输出：

*   << Request  >> 34
-   ReqURL         /test
-   ReqHeader      Accept: */*
-   VCL_call       RECV
-   ReqURL         /test
-   ReqHeader      Accept: text/html
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   VCL_call       MISS
-   VCL_return     fetch
-   RespHeader     Vary: Accept
-   VCL_call       DELIVER
-   VCL_return     deliver
**  << BeReq    >> 35
--  BereqURL       /test
--  BereqHeader    Accept: text/html
--  BereqHeader    Accept-Encoding: gzip
--  VCL_call       BACKEND_FETCH
--  VCL_return     fetch
--  VCL_call       BACKEND_RESPONSE
--  BerespHeader   Vary: Accept
--  VCL_return     deliver

下面是针对普通HTML的缓存命中的情况：

*   << Request  >> 32800
-   ReqURL         /test
-   ReqHeader      Accept: */*
-   VCL_call       RECV
-   ReqURL         /test
-   ReqHeader      Accept: text/html
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   VCL_call       HIT
-   VCL_return     deliver
-   RespHeader     Vary: Accept
-   VCL_call       DELIVER
-   VCL_return     deliver

即使HTML版本仍在缓存中，Accept: application/json也会导致缓存丢失：

*   << Request  >> 32802
-   ReqURL         /test
-   ReqHeader      Accept:application/json
-   VCL_call       RECV
-   ReqURL         /test
-   ReqHeader      Accept: application/json
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   VCL_call       MISS
-   VCL_return     fetch
-   RespHeader     Vary: Accept
-   VCL_call       DELIVER
-   VCL_return     deliver
**  << BeReq    >> 32803
--  BereqURL       /test
--  BereqHeader    Accept: application/json
--  BereqHeader    Accept-Encoding: gzip
--  VCL_call       BACKEND_FETCH
--  VCL_return     fetch
--  VCL_call       BACKEND_RESPONSE
--  BerespHeader   Vary: Accept
--  VCL_return     deliver

下一次，这将对JSON输出造成影响：

*   << Request  >> 32805
-   ReqURL         /test
-   ReqHeader      Accept:application/json
-   VCL_call       RECV
-   ReqURL         /test
-   ReqHeader      Accept: application/json
-   VCL_return     hash
-   VCL_call       HASH
-   VCL_return     lookup
-   VCL_call       HIT
-   VCL_return     deliver
-   RespHeader     Vary: Accept
-   VCL_call       DELIVER
-   VCL_return     deliver