Typically, the best way to ensure that a web application will run correctly in production is to stage it an environment just like production. Most of the time the overhead of setting up caching or other performance improvements is not necessary in development, but there are instances when the development being done directly interacts with or relies upon these components. In these situations it often pays off to take the time to set up "production components" so that changes can be tested prior to pushing changes to a staging or production environment, often a costly extra step.

Today, I am going to focus on setting up Varnish Cache, a "caching HTTP reverse proxy". Varnish allows you to cache responses to quickly serve common pages and provides powerful configuration for response headers and other cache settings.

Installation

If you are using Mac OSX, you can simply use Homebrew to install Varnish.

brew install varnish

If you are using vanilla Varnish without any other modules, you can skip ahead to the usage section. If you do not use brew, continue to follow along and we will install it from source.

Installing Modules

Installing Varnish modules such as libvmod-header or libvmod-cookie requires building them from source using Varnish's source.

First we must build Varnish's source. Download a Varnish from their website or github.

cd /varnish-cache-source-location
./autogen.sh
./configure
make

# install varnish without brew (optional)
make install

Note: If you get an rst2man error during compilation you need to install docutils with pip.

Now that we have built Varnish, we can use it to build our modules. For each module do as follows.

cd /varnish-module-location
./autogen.sh
./configure VARNISHSRC=/path-to-varnish-source
make
make install

This will install the module binaries to the correct location, allowing you to import the module in your vcls. You can now configure default.vcl to your liking. It is located at /user/local/etc/varnish on OSX.

Usage

If you installed Varnish via brew, you can use launchctl and the plist files to load the service, or you can use the varnishd command via the terminal. I recommend using the terminal initially because this will allow you to see and debug any errors. The property list files will fail silently if there are any errors.

# must run as root
sudo varnishd -f /usr/local/etc/varnish/default.vcl -s file -a 0.0.0.0:8000
# help: see available arguments with descriptions
varnishd -h

Command Breakdown

• -f Specifies the location of the vcl script to launch Varnish with.
• -s Specifies storage options. The file argument stores in /tmp by default. You can specify another location with -s file,/location
• -a Specifies the address and port that Varnish will run at. You can access your website through Varnish using this address and port.

By now you should be up and running with Varnish locally on your development environment. For more information on Varnish in general and writing vcl scripts, consult the documentation.