我有一个位于Varnish后面的Plone网站。除了一件事外,一切都正常。
这是一个动态网站,因此会不时有新内容。场景如下:
我有一个显示项目列表的页面。此页面已被缓存。所以我通过某种表单添加了另一个项目,并返回到同一页面,但没有显示新项目。这是因为显示的页面来自缓存,并且仍在其 TTL 中。
如何确保在提交新项目时,该页面将从缓存中清除,并且将显示后端服务器中包含新项目的新页面?
我的简单VCL如下所示:
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,每当我收到 POST 请求时,如何清除或清除域的整个缓存?
您需要自定义 Varnish VCL 以处理PURGE
请求和 Plone CMS,以便在内容更改时向 Varnish 发出清除请求。
开发者文档有关于将 Varnish 与 Plone 一起使用的相当好和全面的文档。您可以根据自己的特定需求进行调整。
文档中的示例解释了如何在 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,以防它们在将来的某个时候从Plone站点中删除:
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,对于 Plone,您可以创建一个自定义视图,用于向 Varnish 发出PURGE
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))
如前所述,这只是按需清除整个缓存。我不是 Plone 的专家,所以我无法就如何使其适应清除特定内容给出详细的答案。基本上,您需要确定在特定情况下需要清除哪些页面,然后调整上面的示例,以便在 Plone 中处理POST
请求时自动向 Varnish 发出PURGE
请求。
仅在VCL中处理清除(即检测开机自检呼叫并基于这些呼叫清除内容)非常复杂。我相信在 Plone 中处理逻辑和清除会更有效。
更新:
如果您希望清除每个POST
上的整个缓存,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以相同主机名缓存的所有页面。不过,我建议从长远来看研究较早的解决方案。在发生POST
时,仅清除实际需要清除的页面要高效得多。