Question

我有一个位于Varnish后面的Plone网站。一切都工作正常，除了一件事。

这是一个动态网站，因此会不时出现新内容。方案如下：

我有一个显示项目列表的页面。此页面已缓存。所以我通过某种形式添加另一个项目，并返回到同一页面，但新项目未显示。这是因为显示的页面来自缓存，并且仍在其TTL内。

如何在提交新项目时确保从缓存中清除该页面，并显示后端服务器中包含新项目的新页面？

我的简单VCL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"; 
    } 
}

或者说白了，每当收到POST请求时，如何清除或清除域的整个缓存？

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Varnish发出清除请求。

Plone开发人员文档在using Varnish with Plone上有非常好的和完整的文档。您可以根据自己的特定需求进行调整。

文档中的示例说明了如何在VCL中创建自定义ACL和regexp清除处理，然后如何在Plone中使用它来清除整个缓存。我已经从这里的例子中复制了VCL和Plone视图，以防万一他们将来某个时候从Plone网站上删除它们：

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，对于Plone，您创建了一个自定义视图，用于向Varnish发出PURGE个请求：

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，这只是按需清除整个缓存。我不是Plone的专家，所以我无法详细解答如何使其适应清除特定内容。基本上，您需要确定在特定情况下需要清除哪些页面，然后调整上述示例，以便在Plone中处理PURGE请求时自动向Varnish发出POST请求。

单独处理VCL中的清除（即检测POST调用并根据这些清除内容）非常复杂。我相信在Plone中处理逻辑和清除会更有效率。

<强>更新

如果您希望在每个POST上清除整个缓存，可以按如下方式完成：

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

现在，每个POST请求都会导致从缓存中清除已缓存在同一主机名下的所有页面。我建议从长远来看，考虑早期的解决方案。在POST发生时，仅清除实际需要清除的页面效率要高得多。

清漆：POST数据后清除缓存

1 个答案: