Extension that will pre-Gzip JS and CSS files. Gzipped assets can be served directly by Apache or Nginx with the proper configuration, and pre-zipping means that we can use a more agressive compression level at no CPU cost per request.

middleman-more/features/gzip.feature

@@ -0,0 +1,18 @@
+Feature: GZIP assets during build
+
+  Scenario: Built assets should be gzipped
+    Given a successfully built app at "gzip-app"
+    Then the following files should exist:
+      | build/javascripts/test.js.gz |
+      | build/stylesheets/test.css.gz |
+      | build/index.html |
+    When I run `file build/javascripts/test.js.gz`
+    Then the output should contain "gzip"
+
+  Scenario: Preview server doesn't change
+    Given the Server is running at "gzip-app"
+    When I go to "/javascripts/test.js"
+    Then I should see "test_function"
+    When I go to "/stylesheets/test.css"
+    Then I should see "test_selector"
+   

middleman-more/fixtures/gzip-app/config.rb

@@ -0,0 +1 @@
+activate :gzip_assets

middleman-more/fixtures/gzip-app/source/javascripts/test.js

@@ -0,0 +1 @@
+function test_function() {}

middleman-more/fixtures/gzip-app/source/stylesheets/test.css

@@ -0,0 +1 @@
+test_selector {}

middleman-more/lib/middleman-more.rb

@@ -40,6 +40,9 @@ module Middleman
 
     # MinifyJavascript uses the YUI compressor to shrink JS files
     autoload :MinifyJavascript,    "middleman-more/extensions/minify_javascript"
+
+    # GZIP assets during build
+    autoload :GzipAssets,    "middleman-more/extensions/gzip_assets"
   end
   
   # Setup renderers
@@ -65,4 +68,6 @@ module Middleman
     ::Middleman::Extensions::MinifyJavascript }
   Extensions.register(:relative_assets) {
     ::Middleman::Extensions::RelativeAssets }
-end
+  Extensions.register(:gzip_assets) {
+    ::Middleman::Extensions::GzipAssets }
+end

middleman-more/lib/middleman-more/extensions/gzip_assets.rb

@@ -0,0 +1,74 @@
+require 'zlib'
+require 'stringio'
+
+module Middleman::Extensions
+  
+  # This extension Gzips assets when building. 
+  # Gzipped assets can be served directly by Apache or
+  # Nginx with the proper configuration, and pre-zipping means that we
+  # can use a more agressive compression level at no CPU cost per request.
+  module GzipAssets
+    class << self
+      def registered(app)
+        return unless app.inst.build?
+
+        app.after_configuration do
+          # Register a reroute transform that adds .gz to asset paths
+          sitemap.reroute do |destination, page|
+            if %w(.js .css).include? page.ext
+              destination + '.gz'
+            else
+              destination
+            end
+          end
+
+          use GzipRack
+        end
+      end
+      alias :included :registered
+    end
+
+    # Rack middleware to GZip asset files
+    class GzipRack
+      
+      # Init
+      # @param [Class] app
+      # @param [Hash] options
+      def initialize(app, options={})
+        @app = app
+      end
+
+      # Rack interface
+      # @param [Rack::Environmemt] env
+      # @return [Array]
+      def call(env)
+        status, headers, response = @app.call(env)
+
+        if env["PATH_INFO"].match(/\.(js|css).gz$/)
+          contents = case(response)
+            when String
+              response
+            when Array
+              response.join
+            when Rack::Response
+              response.body.join
+            when Rack::File
+              File.read(response.path)
+          end
+
+          gzipped = ""
+          StringIO.open(gzipped) do |s|
+            gz = Zlib::GzipWriter.new(s, Zlib::BEST_COMPRESSION)
+            gz.write contents
+            gz.close
+          end
+
+          headers["Content-Length"] = ::Rack::Utils.bytesize(gzipped).to_s
+          response = [gzipped]
+        end
+
+        [status, headers, response]
+      end
+    end
+  end
+end