Use the PORT environment variable for rails server

railties/CHANGELOG.md

+*   `rails server` will now honour the `PORT` environment variable
+
+    *David Cornu*
+
 *   Plugins generated using `rails plugin new` are now generated with the
     version number set to 0.1.0.
 

railties/lib/rails/commands/server.rb

@@ -86,7 +86,7 @@ def middleware
 
     def default_options
       super.merge({
-        Port:               3000,
+        Port:               ENV.fetch('PORT', 3000).to_i,
         DoNotReverseLookup: true,
         environment:        (ENV['RAILS_ENV'] || ENV['RACK_ENV'] || "development").dup,
         daemonize:          false,

railties/test/commands/server_test.rb

@@ -44,6 +44,13 @@ def test_environment_with_rack_env
     end
   end
 
+  def test_environment_with_port
+    switch_env "PORT", "1234" do
+      server = Rails::Server.new
+      assert_equal 1234, server.options[:Port]
+    end
+  end
+
   def test_caching_without_option
     args = []
     options = Rails::Server::Options.new.parse!(args)