Varnish Cache for WordPress on cPanel

[onel0ve]

Varnish is an extremely easy to configure server cache software that can help you counter the ?slashdot effect? ? high traffic over a small period of time. The way Varnish does this is by sitting between the client and the webserver and providing cached results to the client so that the server doesn?t have to process every page. It?s better than memcache etc because the request never gets to the webserver. You can avoid one of the bottlenecks this way. In this tutorial, we?ll cover how to setup Varnish on a VPS (or dedicated server) where you have root access and are running your site using cPanel/WHM. It also applies to situations where you don?t have cPanel/WHM. You can just skip the cPanel portion if that?s the case. So, let?s get started.
First, you need to get Varnish. It?s very easy to setup since it comes with its own repository for CentOS. It does have on dependency that?s normally missing. That dependency is jemalloc.so. When you try to install varnish, it gives the error:
Missing Dependency: libjemalloc.so.1()(64bit) is needed by package varnish-3.0.0-1.el5.x86_64 (varnish-3.0)
Get this file and install it using the following commands:

wget http://download.fedora.redhat.com/pu...el5.x86_64.rpm
rpm -ivh jemalloc-2.1.3-2.el5.x86_64.rpm

Now we have the dependency. Head over to Varnish Docs page and read the instructions for your operating system. Since I?m describing CentOS, here are the instructions for that:

rpm --nosignature -i http://repo.varnish-cache.org/redhat...0-1.noarch.rpm

yum install varnish

Now to edit the varnish configuration file. It?s located at: etc/varnish/default.vcl. Insert the following code in the file. Explanation of the different constructs follows:

backend default {
  .host = "your.primary.domainname.com";
  .port = "80";
}
sub vcl_recv {
  if (req.http.Accept-Encoding) {
    if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|lzma|tbz)(\?.*|)$") {
      remove req.http.Accept-Encoding;
    } elsif (req.http.Accept-Encoding ~ "gzip") {
      set req.http.Accept-Encoding = "gzip";
    } elsif (req.http.Accept-Encoding ~ "deflate") {
      set req.http.Accept-Encoding = "deflate";
    } else {
      remove req.http.Accept-Encoding;
    }
  }
  if (req.url ~ "^/[^?]+\.(jpeg|jpg|png|gif|ico|js|css|txt|gz|zip|lzma|bz2|tgz|tbz|html|htm)(\?.*|)$") {
    unset req.http.cookie;
  }
  if (req.request == "GET" && req.url ~ "cron_job" ||         req.url ~ "something_else"        ) {
    return ( pass );
  }
}

The configuration file is fairly straight forward. Just a couple of things that need explanation. Backend defines your webserver. You can have multiple backends and load balance between them but I?m not covering that here. Read up on varnish docs for that.
The sub vcl_recv portion gets called before a request gets passed to the backend or gets checked in the cache. You can define different rules here. For example, the rule if (req.url ~ "^/[^?]+\.(jpeg| ... says that if the requested URL matches one of those extensions, the http cookie should be unset. This is important because if a cookie is present in any request, varnish will always bypass the cache and send the request to the webserver. By unsetting the cookie, you?re giving varnish a chance to check if a cache hit will occur.
The second important line here is the return(pass); directive. Whenever this gets called, the cache is ignored again and the request is passed through to the webserver. In our case, if the request URL contains either the word ?cron_job? or ?something_else?, it gets ignored by varnish. You might want to do this if (as in this case), there?s a cron job that does not have a cookie but still needs to be called on the webserver each time.
Ok, enough talk. Let?s start varnish. Here?s the command:
varnishd -f /etc/varnish/default.vcl -s malloc,1G -T 127.0.0.1:2000 -a 0.0.0.0:8080
It reads the configuration file given by the -f directive, allocates 1GB memory to varnish, sets up an admin interface on port 2000 and sets up the varnish listening port on 8080. Notice that we currently have varnish set on 8080 and the webserver on 80. This is so that we can test varnish without disrupting the normal processing of the server. After we?re done testing, we?ll change the webserver to 8080 and varnish to 80.
To see the status of varnish request processing, run varnishtop on the shell and send a request to your server on port 8080.
To configure a running instance of varnish, you can use the varnishadm command. For example, run varnishadm and issue the following commands to reload the configuration file (after you?ve made some changes to it).
help

vcl.load reload01 /etc/varnish/default.vcl
vcl.use reload01

Finally, when you have everything ready, it?s time to kill varnish, change the server port to 8080 and re-run varnish on port 80. First,
killall varnishd
Edit the configuration file and change backend port to 8080 instead of 80.

cPanel/WHM configuration

This one?s easy. If you?re just using apache, change all listening ports to 8080 and change your vhost directives. If you?re using cPanel/WHM, go to WHM -> Tweak Settings and change ?Apache non-SSL IP/port? to ?0.0.0.0:8080″. (If you have apache listening on a specific IP, you can change the 0s accordingly).
Now, save, restart apache and issue the following command to start varnish:

varnishd -f /etc/varnish/default.vcl -s malloc,1G -T 127.0.0.1:2000 -a 0.0.0.0:80

You should now be able to browse the site and check varnishtop to see that varnish is processing the requests. You might also want to put the command (prefixing it with /usr/bin/varnishd instead of varnishd) in /etc/rc.local so that varnish starts on reboot.

onel0ve Reviewed by onel0ve on 5th Dec 2011. Varnish Cache for WordPress on cPanel Varnish is an extremely easy to configure server cache software that can help you counter the ?slashdot effect? ? high traffic over a small period of time. The way Varnish does this is by sitting between the client and the webserver and providing cached results to the client so that the server doesn?t have to process every page. It?s better than memcache etc because the request never gets to the webserver. You can avoid one of the bottlenecks this way. In this tutorial, we?ll cover how Rating: 5

[LuDo8]

I'm trying to get Nginx working with Varnish. I have Varnish set on Port 80, and in Nginx.conf to port 8080. Saved and rebooted all services.

So my question is:

How do I know Varnish is Working? VS my website being just served up by Nginx. If I visit mydomain.com:80 the site loads, if I go to mydomain.com:8080 I got 403 Forbidden.

I also ran Varnishtop command and this is what I get:

list length 35

    15.23 CLI            Rd ping
     0.98 CLI            Wr 200 19 PONG 1326338445 1.0
     0.95 CLI            Wr 200 19 PONG 1326338442 1.0
     0.92 CLI            Wr 200 19 PONG 1326338439 1.0
     0.89 CLI            Wr 200 19 PONG 1326338436 1.0
     0.87 CLI            Wr 200 19 PONG 1326338433 1.0
     0.83 CLI            Wr 200 19 PONG 1326338430 1.0
     0.81 CLI            Wr 200 19 PONG 1326338427 1.0
     0.79 CLI            Wr 200 19 PONG 1326338424 1.0
     0.76 CLI            Wr 200 19 PONG 1326338421 1.0
     0.74 CLI            Wr 200 19 PONG 1326338418 1.0
     0.72 CLI            Wr 200 19 PONG 1326338415 1.0
     0.70 CLI            Wr 200 19 PONG 1326338412 1.0
     0.69 CLI            Wr 200 19 PONG 1326338409 1.0
     0.67 CLI            Wr 200 19 PONG 1326338406 1.0
     0.65 CLI            Wr 200 19 PONG 1326338403 1.0
     0.64 CLI            Wr 200 19 PONG 1326338400 1.0
     0.62 CLI            Wr 200 19 PONG 1326338397 1.0
     0.60 CLI            Wr 200 19 PONG 1326338394 1.0
     0.59 CLI            Wr 200 19 PONG 1326338391 1.0
     0.57 CLI            Wr 200 19 PONG 1326338388 1.0
     0.55 CLI            Wr 200 19 PONG 1326338385 1.0 

So judging from those PONGS its not working right?

[snowmanrene]

Why are you running Varnish on port 80 though.

The better setup I've seen and used is Nginx + Apache + Varnish.
Nginx handles static content, any dynamic content is passed through to Apache and if Apache is under load, Varnish displays the cache instead.

Nginx:80
Varnish:6081
Apache:8080

[LuDo8]

onel0ve's tutorial says..

Notice that we currently have varnish set on 8080 and the webserver on 80. This is so that we can test varnish without disrupting the normal processing of the server. After we?re done testing, we?ll change the webserver to 8080 and varnish to 80.

So I put it to port 80, but I'll be okay with any port as long as it works faster!!

I'll just be running Wordpress sites with W3 Total Cache to generate static files for Nginx and the caching for Varnish. Trying not to use Apache to minimize footprint and conserve as much resources as possible for the sites, and future growth.

I've Googled and followed tutorials on getting Nginx, Wordpress and W3 Total Cache working, but I can't seem to find anything easily understandable on how to add Varnish into the mix.

Some guidance would be very much appreciated, thanks in advance =]

[LuDo8]

Nada? Nothing? Where's all the server guru's at!