Thursday, March 19, 2009

Setting up a FreeBSD 6.2 Web Server: Proxy Caching (Part 7)

Okay I lied, eAccelerator gives a pretty darn high ROI, but setting up a proxy cache gives a comparable or higher ROI. I chose to use Varnish as my proxy cache.

Once installed, Varnish will keep a cache of all objects requested by internet users (e.g. post-generated PHP pages, CSS, javascripts, images) with the goal of off-loading some work from your web server (remember: we won’t want big Apache to do the work only if it has to). Also Varnish takes full advantage of the OS’s virtual memory and advanced I/O features on FreeBSD 6.x making it the optimal choice for my setup.

There were many confusing instructions on the web about how to configure Varnish. Here are the steps I took to setting up Varnish for a signal machine running both Varnish and the web server:

1) Port install Varnish.

cd /usr/ports/www/varnish/; make install clean
2) Change Apache’s port to 8080 by modifying this line in /usr/local/etc/apache/httpd.conf

Listen 8080
3) Restart Apache

/usr/local/etc/rc.d/apache22 restart
4) Start the Varnish daemon. Substitute the IP below with your machine’s internal network IP address. If you are hosting at home, it is most likely 192.168.0.* but you can run ifconfig to find out what it is.

varnishd -a :80 -b localhost:8080
That’s it! From now, all requests on port 80 should now be routed through the Varnish proxy cache. A proxy cache miss will seemlessly make Apache calls to serve the internet user without the user ever knowing it! A proxy cache hit would not access Apache (and therefore not access MySQL) lessening your machine CPU usage and increasing the speed & efficiency of serving objects to user.

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