清漆：POST数据后清除缓存

Question

我有一个位于光油后面的Plone网站。除了一件事外，所有的工作都可以。

这是一个动态网站，因此会不时有新的内容。场景如下：

我有一个显示项目列表的页面。此页面已被缓存。因此，我通过某种形式添加了另一个项目，并返回到同一页面，但未显示新项目。这是因为显示的页面来自缓存并且仍在TTL内。

如何确保在提交新项目时，该页面将从缓存中清除，并且将显示来自后端服务器的具有新项目的新页面？

我简单的VCL被如图所示：

backend default { 
    .host = "127.0.0.1"; 
    .port = "8080"; 
} 

sub vcl_recv { 
    if (req.request != "GET" && req.request != "HEAD") { 
     # We only deal with GET and HEAD by default 
     return (pass); 
    } 

    # remove unnecessary cookies 
    if (req.http.cookie ~ "wc.cookiecredentials|Path|Domain") { 
     # found wc.cookiecredentials in request, passing to backend server 
     return (lookup); 
    } else { 
     unset req.http.cookie; 
    } 
} 

sub vcl_fetch { 
    #unset beresp.http.Set-Cookie; 
    set beresp.ttl = 12h; 
    return(deliver); 
} 

# Routine used to determine the cache key if storing/retrieving a cached page. 
sub vcl_hash { 
    # Do NOT use this unless you want to store per-user caches. 
    if (req.http.Cookie) { 
     set req.hash += req.http.Cookie; 
    } 
} 

sub vcl_deliver { 
    # send some handy statistics back, useful for checking cache 
    if (obj.hits > 0) { 
     set resp.http.X-Cache-Action = "HIT"; 
     set resp.http.X-Cache-Hits = obj.hits; 
    } else { 
     set resp.http.X-Cache-Action = "MISS"; 
    } 
} 

还是把它说白了，我怎么能清除或清除整个缓存域每当我收到一个POST请求？

Answer 1

要完成此操作，您需要自定义Varnish VCL以处理PURGE请求和您的Plone CMS，以便在内容更改时向清漆发出清除请求。

Plone Developer Documentation在using Varnish with Plone上有非常好的和全面的文档。您可以根据自己的具体需求进行调整。

本文档中的示例介绍了如何在VCL中创建自定义ACL和正则表达式清除处理，以及如何在Plone中使用该清除来清除整个高速缓存。我从这里的例子复制的VCL和Plone观点，以防万一，他们得到来自Plone站点在未来一段时间内删除：

acl purge { 
     "localhost"; 
     # XXX: Add your local computer public IP here if you 
     # want to test the code against the production server 
     # from the development instance 
} 

... 

sub vcl_recv { 

     ... 

     # Allow PURGE requests clearing everything 
     if (req.request == "PURGE") { 
       if (!client.ip ~ purge) { 
         error 405 "Not allowed."; 
       } 
       # Purge for the current host using reg-ex from X-Purge-Regex header 
       purge("req.http.host == " req.http.host " && req.url ~ " req.http.X-Purge-Regex); 
       error 200 "Purged."; 
     } 
} 

然后为Plone创建自定义视图发放PURGE请求光油：

import requests 

from Products.CMFCore.interfaces import ISiteRoot 
from five import grok 

from requests.models import Request 

class Purge(grok.CodeView): 
    """ 
    Purge upstream cache from all entries. 

    This is ideal to hook up for admins e.g. through portal_actions menu. 

    You can access it as admin:: 

     http://site.com/@@purge 

    """ 

    grok.context(ISiteRoot) 

    # Onlyl site admins can use this 
    grok.require("cmf.ManagePortal") 

    def render(self): 
     """ 
     Call the parent cache using Requets Python library and issue PURGE command for all URLs. 

     Pipe through the response as is. 
     """ 

     # This is the root URL which will be purged 
     # - you might want to have different value here if 
     # your site has different URLs for manage and themed versions 
     site_url = self.context.portal_url() + "/" 

     headers = { 
        # Match all pages 
        "X-Purge-Regex" : ".*" 
     } 

     resp = requests.request("PURGE", site_url + "*", headers=headers) 

     self.request.response["Content-type"] = "text/plain" 
     text = [] 

     text.append("HTTP " + str(resp.status_code)) 

     # Dump response headers as is to the Plone user, 
     # so he/she can diagnose the problem 
     for key, value in resp.headers.items(): 
      text.append(str(key) + ": " + str(value)) 

     # Add payload message from the server (if any) 

     if hasattr(resp, "body"): 
       text.append(str(resp.body)) 

如上所述，这只是简单地按需清除整个缓存。我不是Plone的专家，所以我无法给你一个详细的答案，就如何调整它来清除特定的内容。基本上，您需要确定在特定情况下需要清除哪些页面，然后修改上述示例，以便在Plone中处理POST请求时自动向Varnish发出PURGE请求。

单独处理VCL中的清除（即检测POST调用和基于这些清除内容）非常复杂。我相信它将更有效地处理Plone中的逻辑和清除。

更新：

如果你要清除每POST整个缓存，这可以完成如下。

sub vcl_recv { 
    if (req.request == "POST") { 
     ban("req.http.host == " + req.http.Host); 
     return(pass); 
    } 
} 

现在每POST请求导致从缓存中清除已在同一主机名下缓存所有页面。尽管如此，我仍然建议从长远来看早期的解决方案。当发生POST时，仅清除实际需要清除的页面会更有效。