Purge Varnish Cache when post content on your site is modified.
This was built and tested on Varnish 3.x, however it is reported to work on 2.x and 4.x. It is only supported on v3 at this time.
The only pages that should purge are the post's page, the front page, categories, and tags. The reason why is a little philosophical.
When building out this plugin, there were a couple pathways on how best to handle purging caches and they boiled down to two: Decisions (the plugin purges what it purges when it purges) and Options (you decide what to purge, when and why). It's entirely possible to make this plugin purge everything, every time a 'trigger' happens, have it purge some things, or have it be so you can pick that purges.
In the interests of design, we decided that the KISS principle was key. Since you can configure your Varnish to always purge all pages recursively (i.e. purging http://example.com/ would purge all pages below it), if that's a requirement, you can set it yourself. There are also other Varnish plugins that allow for more granular control (including W3 Total Cache), however this plugin will not be gaining a whole bunch of options to handle that.
Because the plugin only purges your content when you edit it. That means if you edit a page/post, or someone leaves a comment, it'll change. Otherwise, you have to purge the whole cache. The plugin will do this for you if you ''change'' your theme, but not when you edit your theme.
If you use Jetpack's CSS editor, it will purge the whole cache for your site on save.
Click the 'Purge Varnish Cache' button on the "Right Now" Dashboard (see the screenshot if you can't find it).
There's also a "Purge Varnish" button on the admin toolbar.
If you're on a Multisite Network and you're on the primary site in the network, only the network admins can purge that site
On a subfolder network if you flush the site at
example.com, then everything under that (like
example.com/siten and everything else) would also get flushed. That means that a purge on the main site purges the entire network.
In order to mitigate the destructive nature of that power, only the network admins can purge everything on the main site of a subfolder network.
PageSpeed likes to put in Caching headers to say not to cache. To fix this, you need to put this in your .htaccess section for PageSpeed:
If you're using nginx, it's
pagespeed ModifyCachingHeaders off;
Yes, but you'll need to make some additional changes (see "Why aren't my changes showing when I use CloudFlare or another proxy?" below).
When you use CloudFlare or any other similar service, you've got a proxy in front of the Varnish proxy. In general this isn't a bad thing. The problem arises when the DNS shenanigans send the purge request to your domain name. When you've got an additional proxy like CloudFlare, you don't want the request to go to the proxy, you want it to go to Varnish server.
To fix this, add the following to your wp-config.php file:
Replace "184.108.40.206" with the IP of your Varnish Server (not CloudFlare, Varnish). DO NOT put in http in this define.
You can also set the option
vhp_varnish_ip in the database. This will NOT take precedence over the define, it's just there to let hosts who are using something like wp-cli do this for you in an automated fashion:
wp option add vhp_varnish_ip 220.127.116.11
wp option update vhp_varnish_ip 18.104.22.1680
Your Varnish IP must be one of the IPs that Varnish is listening on. If you use multiple IPs, or if you've customized your ACLs, you'll need to pick on that doesn't conflict with your other settings. For example, if you have Varnish listening on a public and private IP, you'll want to pick the private. On the other hand, if you told Varnish to listen on 0.0.0.0 (i.e. "listen on every interface you can") you would need to check what IP you set your purge ACL to allow (commonly 127.0.0.1 aka localhost), and use that (i.e. 127.0.0.1).
If your webhost set up Varnish for you, you may need to ask them for the specifics if they don't have it documented. I've listed the ones I know about here, however you should still check with them if you're not sure.
Multiple IPs are not supported at this time.
I have a major issue with writing code I don't use, which means that since I'm only using one IP right now, I don't want to be on the ball for supporting multiple IPs. I don't even have a place to test is, which is just insane to attempt to code if you think about it. Yes, I could accept pull requests, but that means everyone's at some other person's discretion. So no, I won't be doing that at this time.
Make sure your Varnish VCL is configured correctly to purge all the right pages. This is normally an issue with Varnish 2, which is not supported by this plugin.
The plugin sends a PURGE command of
X-Purge-Method in the header with a value of regex. If your Varnish server doesn't doesn't understand the wildcard, you can configure it to check for the header.
WP_DEBUG is on and you're not seeing any errors, you'll have to jump into the command line.
To see every request made to varnish, use this:
varnishncsa -F "%m %U"
If you want to grab the last purge requests, it's this:
varnishlog -d -c -m RxRequest:PURGE
And this will show you if the WP button was used:
varnishlog -d -c -m RxURL:.*vhp_flush_all.*
In general, I leave the first command up and test the plugin.
A full Varnish flush looks like this:
And a new-post (or edited post) would look like this:
It's just a matter of poking at things from then on.
This is a question beyond the support of plugin. I don't offer any Varnish Config help due to resources. I will say this, you absolutely must have PURGE set up in your VCL. This is still supported in Varnish v3, though may not be set up by default. Also, here are some links to other people who use this plugin and have made public their VCLs:
All of these VCLs work with this plugin.
If you're using
varnish_http_purge_events then you have to make sure your event spits out a post ID.
Requires: 4.0 or higher
Compatible up to: 4.5.3
Last Updated: 4 months ago
Active Installs: 30,000+
1 of 5 support threads in the last two months have been marked resolved.
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