Merge pull request #16466 from schneems/schneems/gzip-action-dispatch

Enable gzip compression by default

actionpack/CHANGELOG.md

+*   Requests that hit `ActionDispatch::Static` can now take advantage
+    of gzipped assets on disk. By default a gzip asset will be served if
+    the client supports gzip and a compressed file is on disk.
+
+    *Richard Schneeman*
+
 *   `ActionController::Parameters` will stop inheriting from `Hash` and
     `HashWithIndifferentAccess` in the next major release. If you use any method
     that is not available on `ActionController::Parameters` you should consider

actionpack/lib/action_dispatch/middleware/static.rb

@@ -16,8 +16,9 @@ class FileHandler
     def initialize(root, cache_control)
       @root          = root.chomp('/')
       @compiled_root = /^#{Regexp.escape(root)}/
-      headers = cache_control && { 'Cache-Control' => cache_control }
-      @file_server   = ::Rack::File.new(@root, headers)
+      headers        = {}
+      headers['Cache-Control'] = cache_control if cache_control
+      @file_server = ::Rack::File.new(@root, headers)
     end
 
     def match?(path)
@@ -36,23 +37,48 @@ def match?(path)
     end
 
     def call(env)
-      @file_server.call(env)
+      path             = env['PATH_INFO']
+      gzip_file_exists = gzip_file_exists?(path)
+      if gzip_file_exists && gzip_encoding_accepted?(env)
+        env['PATH_INFO'] = "#{path}.gz"
+        status, headers, body       = @file_server.call(env)
+        headers['Content-Encoding'] = 'gzip'
+        headers['Content-Type']     = content_type(path)
+      else
+        status, headers, body = @file_server.call(env)
+      end
+
+      headers['Vary'] = 'Accept-Encoding' if gzip_file_exists
+      return [status, headers, body]
     end
 
-    def ext
-      @ext ||= begin
-        ext = ::ActionController::Base.default_static_extension
-        "{,#{ext},/index#{ext}}"
+    private
+      def ext
+        @ext ||= begin
+          ext = ::ActionController::Base.default_static_extension
+          "{,#{ext},/index#{ext}}"
+        end
       end
-    end
 
-    def unescape_path(path)
-      URI.parser.unescape(path)
-    end
+      def unescape_path(path)
+        URI.parser.unescape(path)
+      end
 
-    def escape_glob_chars(path)
-      path.gsub(/[*?{}\[\]]/, "\\\\\\&")
-    end
+      def escape_glob_chars(path)
+        path.gsub(/[*?{}\[\]]/, "\\\\\\&")
+      end
+
+      def content_type(path)
+        ::Rack::Mime.mime_type(::File.extname(path), 'text/plain')
+      end
+
+      def gzip_encoding_accepted?(env)
+        env['HTTP_ACCEPT_ENCODING'] =~ /\bgzip\b/
+      end
+
+      def gzip_file_exists?(path)
+        File.exist?(File.join(@root, "#{::Rack::Utils.unescape(path)}.gz"))
+      end
   end
 
   # This middleware will attempt to return the contents of a file's body from

actionpack/test/dispatch/static_test.rb

 # encoding: utf-8
 require 'abstract_unit'
 require 'rbconfig'
+require 'zlib'
 
 module StaticTests
   def test_serves_dynamic_content
@@ -106,6 +107,18 @@ def test_serves_static_file_with_at_symbol_in_filename
     end
   end
 
+  def test_serves_gzip_files_when_header_set
+    file_name = "/gzip/application-a71b3024f80aea3181c09774ca17e712.js"
+    response  = get(file_name, 'HTTP_ACCEPT_ENCODING' => 'gzip')
+    assert_gzip  file_name, response
+    assert_equal 'application/javascript', response.headers['Content-Type']
+    assert_equal 'Accept-Encoding',        response.headers["Vary"]
+    assert_equal 'gzip',                   response.headers["Content-Encoding"]
+
+    response  = get(file_name, 'HTTP_ACCEPT_ENCODING' => '')
+    refute_equal 'gzip', response.headers["Content-Encoding"]
+  end
+
   # Windows doesn't allow \ / : * ? " < > | in filenames
   unless RbConfig::CONFIG['host_os'] =~ /mswin|mingw/
     def test_serves_static_file_with_colon
@@ -125,13 +138,20 @@ def test_serves_static_file_with_asterisk
 
   private
 
+    def assert_gzip(file_name, response)
+      expected = File.read("#{FIXTURE_LOAD_PATH}/#{public_path}" + file_name)
+      actual   = Zlib::GzipReader.new(StringIO.new(response.body)).read
+      assert_equal expected, actual
+    end
+
     def assert_html(body, response)
       assert_equal body, response.body
       assert_equal "text/html", response.headers["Content-Type"]
+      refute response.headers.key?("Vary")
     end
 
-    def get(path)
-      Rack::MockRequest.new(@app).request("GET", path)
+    def get(path, headers = {})
+      Rack::MockRequest.new(@app).request("GET", path, headers)
     end
 
     def with_static_file(file)