Compressible

Ready-to-go Asset Compression for Ruby, using the YUICompressor.

sudo gem install compressible

Usage

Configuration

There are a few ways you can configure this

1. Initializers

Inside an initializer such as config/compressible.rb:

Compressible.stylesheets(
  :production_cache => %w(reset background footer list),
  :typography => %w(forms headers basic_text)
)
Compressible.javascripts(
  :production_cache => %w(animations effects dragdrop)
)

# or
Compressible.assets(
  :stylesheets => {
    :production_cache => %w(reset background footer list),
    :typography => %w(forms headers basic_text)
  }
  :javascripts => {
    :production_cache => %w(animations effects dragdrop)
  }
)

# or one at a time
Compressible.stylesheet(
  :production_cache => %w(reset background footer list)
)
Compressible.stylesheet(
  :typography => %w(forms headers basic_text)
)

Each of those methods have plenty of aliases to be more descriptive and more concise, respectively:

• stylesheets: add_stylesheets
• javascripts: add_javascripts
• stylesheet: add_stylesheet, css
• javascript: add_javascript, js

Or you can call them generically:

Compressible.assets(:stylesheet)
Compressible.assets(:javascript)

2. Yaml

You can specify these same configuration options using Yaml:

js:
  paths:
    - animations
    - effects
    - dragdrop
  to: production_cache
  munge: true
css:
  -
    paths:
      - reset
      - background
      - footer
      - list
    to: production_cache
  -
    paths:
      - forms
      - headers
      - basic_text
    to: typography

You can then setup everything with configure:

Compressible.configure("config/compressible.yml") # or pass it the yaml hash

Views

Add this to your views:

compressible_stylesheet_tag "production_cache", "typography"
compressible_javascript_tag "production_cache"

By default, it will use non-compressed stylesheets when Rails.env == "development", and the compressed stylesheets when Rails.env == "production".

To tell it you want to use the cached in a different environment, you can specify it like this:

compressible_stylesheet_tag "production_cache", :environments => ["production", "staging"]

Awesome Assets for Heroku

Because Heroku is a Read-Only file system, you can't use Rails' built in asset cacher, or libraries like asset_packager. They rely on the ability to write to the file system in the production environment.

Some libraries solve this by patching asset_packager to redirect css/js urls to the /tmp directory using Rack middleware. The /tmp directory is about the only place Heroku lets you write to the file system in. The main issue with this approach is that all requests for stylesheets and javascripts must pass through Rack, which potentially doubles response time. Take a look at the asset loading performance comparison with different Ruby stacks.

As such, Compressible compresses all assets before you push to Heroku, so a) you never write to the Heroku file system, and b) you don't have slow down the request with application or middleware layers. It does this with git hooks. Every time you commit, a pre-commit hook runs which re-compresses your assets. That means whenever you push, your assets are ready for production.

This is configurable. It relies on the hookify gem.

sudo gem install hookify
cd my-rails-app
hookify pre-commit
mate config/hooks/pre_commit.rb

That creates a ruby script for you were you can define what you want to run when. Add this to the config/hooks/pre_commit.rg file:

require 'rubygems'
gem "activesupport", "= 2.3.5"
require "active_support"
require 'compressible'

Compressible.configure(
  :stylesheet_path => "public/stylesheets",
  :javascript_path => "public/javascripts"
)

Compressible.stylesheets(
  :production_cache => %w(reset background footer list)
)
Compressible.javascripts(
  :production_cache => %w(interface jquery.anytime)
)

Now stylesheets and javascripts compress using the YUICompressor every time you commit. And it's fast. Very cool.