Allow static asset serving from env variable (enhanced!)

guides/source/asset_pipeline.md

@@ -167,9 +167,8 @@ directory. Files in this directory are served by the Sprockets middleware.
 
 Assets can still be placed in the `public` hierarchy. Any assets under `public`
 will be served as static files by the application or web server when
-`config.serve_static_assets` is set to true. You should use
-`app/assets` for files that must undergo some pre-processing before they are
-served.
+`config.serve_static_files` is set to true. You should use `app/assets` for
+files that must undergo some pre-processing before they are served.
 
 In production, Rails precompiles these files to `public/assets` by default. The
 precompiled copies are then served as static assets by the web server. The files

guides/source/configuring.md

@@ -120,7 +120,7 @@ numbers. New applications filter out passwords by adding the following `config.f
 
 * `secrets.secret_key_base` is used for specifying a key which allows sessions for the application to be verified against a known secure key to prevent tampering. Applications get `secrets.secret_key_base` initialized to a random key present in `config/secrets.yml`.
 
-* `config.serve_static_assets` configures Rails itself to serve static assets. Defaults to true, but in the production environment is turned off as the server software (e.g. NGINX or Apache) used to run the application should serve static assets instead. Unlike the default setting set this to true when running (absolutely not recommended!) or testing your app in production mode using WEBrick. Otherwise you won't be able use page caching and requests for files that exist regularly under the public directory will anyway hit your Rails app.
+* `config.serve_static_files` configures Rails itself to serve static files. Defaults to true, but in the production environment is turned off as the server software (e.g. NGINX or Apache) used to run the application should serve static assets instead. Unlike the default setting set this to true when running (absolutely not recommended!) or testing your app in production mode using WEBrick. Otherwise you won't be able use page caching and requests for files that exist regularly under the public directory will anyway hit your Rails app.
 
 * `config.session_store` is usually set up in `config/initializers/session_store.rb` and specifies what class to use to store the session. Possible values are `:cookie_store` which is the default, `:mem_cache_store`, and `:disabled`. The last one tells Rails not to deal with sessions. Custom session stores can also be specified:
 

guides/source/rails_on_rack.md

@@ -233,7 +233,7 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 **`ActionDispatch::Static`**
 
-* Used to serve static assets. Disabled if `config.serve_static_assets` is `false`.
+* Used to serve static files. Disabled if `config.serve_static_files` is `false`.
 
 **`Rack::Lock`**
 

railties/CHANGELOG.md

@@ -1,3 +1,14 @@
+*   Deprecate `config.serve_static_assets` in favor of `config.serve_public_assets`
+    to clarify that the option is unrelated to the asset pipeline.
+
+    *Godfrey Chan*
+
+*   `config.serve_static_assets` can now be set from an environment variable in
+    production mode. The feature remains off by default, but can be enabled by
+    setting `RAILS_SERVE_STATIC_FILES` to a non-empty string at boot time.
+
+    *Richard Schneeman*, *Godfrey Chan*
+
 *   Generated migrations add the appropriate foreign key constraints to
     references.
 

railties/lib/rails/application/configuration.rb

@@ -1,5 +1,7 @@
 require 'active_support/core_ext/kernel/reporting'
+require 'active_support/core_ext/string/filters'
 require 'active_support/file_update_checker'
+require 'active_support/deprecation'
 require 'rails/engine/configuration'
 require 'rails/source_annotation_extractor'
 
@@ -11,7 +13,7 @@ class Configuration < ::Rails::Engine::Configuration
                     :eager_load, :exceptions_app, :file_watcher, :filter_parameters,
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags,
                     :railties_order, :relative_url_root, :secret_key_base, :secret_token,
-                    :serve_static_assets, :ssl_options, :static_cache_control, :session_options,
+                    :serve_static_files, :ssl_options, :static_cache_control, :session_options,
                     :time_zone, :reload_classes_only_on_change,
                     :beginning_of_week, :filter_redirect, :x
 
@@ -25,7 +27,7 @@ def initialize(*)
         @filter_parameters             = []
         @filter_redirect               = []
         @helpers_paths                 = []
-        @serve_static_assets           = true
+        @serve_static_files            = true
         @static_cache_control          = nil
         @force_ssl                     = false
         @ssl_options                   = {}
@@ -139,6 +141,25 @@ def colorize_logging=(val)
         self.generators.colorize_logging = val
       end
 
+      # :nodoc:
+      SERVE_STATIC_ASSETS_DEPRECATION_MESSAGE = <<-MSG.squish
+        The configuration option `config.serve_static_assets` has been renamed
+        to `config.serve_static_files` to clarify its role (it merely enables
+        serving everything in the `public` folder and is unrelated to the asset
+        pipeline). The `serve_static_assets` alias will be removed in Rails 5.0.
+        Please migrate your configuration files accordingly.
+      MSG
+
+      def serve_static_assets
+        ActiveSupport::Deprecation.warn SERVE_STATIC_ASSETS_DEPRECATION_MESSAGE
+        serve_static_files
+      end
+
+      def serve_static_assets=(value)
+        ActiveSupport::Deprecation.warn SERVE_STATIC_ASSETS_DEPRECATION_MESSAGE
+        self.serve_static_files = value
+      end
+
       def session_store(*args)
         if args.empty?
           case @session_store

railties/lib/rails/application/default_middleware_stack.rb

@@ -17,7 +17,7 @@ def build_stack
 
           middleware.use ::Rack::Sendfile, config.action_dispatch.x_sendfile_header
 
-          if config.serve_static_assets
+          if config.serve_static_files
             middleware.use ::ActionDispatch::Static, paths["public"].first, config.static_cache_control
           end
 

railties/lib/rails/generators/rails/app/templates/config/environments/production.rb.tt

@@ -20,8 +20,9 @@ Rails.application.configure do
   # NGINX, varnish or squid.
   # config.action_dispatch.rack_cache = true
 
-  # Disable Rails's static asset server (Apache or NGINX will already do this).
-  config.serve_static_assets = false
+  # Disable serving static files from the `/public` folder by default since
+  # Apache or NGINX already handles this.
+  config.serve_static_files = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
   <%- unless options.skip_sprockets? -%>
   # Compress JavaScripts and CSS.

railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt

@@ -12,8 +12,8 @@ Rails.application.configure do
   # preloads Rails for running tests, you may have to set it to true.
   config.eager_load = false
 
-  # Configure static asset server for tests with Cache-Control for performance.
-  config.serve_static_assets  = true
+  # Configure static file server for tests with Cache-Control for performance.
+  config.serve_static_files   = true
   config.static_cache_control = 'public, max-age=3600'
 
   # Show full error reports and disable caching.

railties/test/application/assets_test.rb

@@ -225,7 +225,7 @@ class User < ActiveRecord::Base; raise 'should not be reached'; end
 
     test "assets do not require any assets group gem when manifest file is present" do
       app_file "app/assets/javascripts/application.js", "alert();"
-      add_to_env_config "production", "config.serve_static_assets = true"
+      add_to_env_config "production", "config.serve_static_files = true"
 
       ENV["RAILS_ENV"] = "production"
       precompile!

railties/test/application/configuration_test.rb

@@ -41,14 +41,23 @@ def app
     def setup
       build_app
       boot_rails
-      FileUtils.rm_rf("#{app_path}/config/environments")
+      supress_default_config
     end
 
     def teardown
       teardown_app
       FileUtils.rm_rf(new_app) if File.directory?(new_app)
     end
 
+    def supress_default_config
+      FileUtils.mv("#{app_path}/config/environments", "#{app_path}/config/__environments__")
+    end
+
+    def restore_default_config
+      FileUtils.rm_rf("#{app_path}/config/environments")
+      FileUtils.mv("#{app_path}/config/__environments__", "#{app_path}/config/environments")
+    end
+
     test "Rails.env does not set the RAILS_ENV environment variable which would leak out into rake tasks" do
       require "rails"
 
@@ -280,6 +289,53 @@ def assert_utf8
       assert_equal Pathname.new(app_path).join("somewhere"), Rails.public_path
     end
 
+    test "In production mode, config.serve_static_files is off by default" do
+      restore_default_config
+
+      with_rails_env "production" do
+        require "#{app_path}/config/environment"
+        assert_not app.config.serve_static_files
+      end
+    end
+
+    test "In production mode, config.serve_static_files is enabled when RAILS_SERVE_STATIC_FILES is set" do
+      restore_default_config
+
+      with_rails_env "production" do
+        switch_env "RAILS_SERVE_STATIC_FILES", "1" do
+          require "#{app_path}/config/environment"
+          assert app.config.serve_static_files
+        end
+      end
+    end
+
+    test "In production mode, config.serve_static_files is disabled when RAILS_SERVE_STATIC_FILES is blank" do
+      restore_default_config
+
+      with_rails_env "production" do
+        switch_env "RAILS_SERVE_STATIC_FILES", " " do
+          require "#{app_path}/config/environment"
+          assert_not app.config.serve_static_files
+        end
+      end
+    end
+
+    test "config.serve_static_assets is deprecated" do
+      require "#{app_path}/config/application"
+
+      assert_deprecated(/serve_static_assets/) do
+        app.config.serve_static_assets = false
+      end
+
+      assert_not app.config.serve_static_files
+      assert_deprecated(/serve_static_assets/) { assert_not app.config.serve_static_assets }
+
+      app.config.serve_static_files = true
+
+      assert app.config.serve_static_files
+      assert_deprecated(/serve_static_assets/) { assert app.config.serve_static_assets }
+    end
+
     test "Use key_generator when secret_key_base is set" do
       make_basic_app do |app|
         app.secrets.secret_key_base = 'b3c631c314c0bbca50c1b2843150fe33'

railties/test/application/middleware/sendfile_test.rb

@@ -61,7 +61,7 @@ def index
     test "files handled by ActionDispatch::Static are handled by Rack::Sendfile" do
       make_basic_app do |app|
         app.config.action_dispatch.x_sendfile_header = 'X-Sendfile'
-        app.config.serve_static_assets = true
+        app.config.serve_static_files = true
         app.paths["public"] = File.join(rails_root, "public")
       end
 

railties/test/application/middleware_test.rb

@@ -113,8 +113,8 @@ def app
       assert !middleware.include?("Rack::Lock")
     end
 
-    test "removes static asset server if serve_static_assets is disabled" do
-      add_to_config "config.serve_static_assets = false"
+    test "removes static asset server if serve_static_files is disabled" do
+      add_to_config "config.serve_static_files = false"
       boot!
       assert !middleware.include?("ActionDispatch::Static")
     end

railties/test/railties/engine_test.rb

@@ -1210,7 +1210,7 @@ def foo
 
     test "engine can be properly mounted at root" do
       add_to_config("config.action_dispatch.show_exceptions = false")
-      add_to_config("config.serve_static_assets = false")
+      add_to_config("config.serve_static_files = false")
 
       @plugin.write "lib/bukkits.rb", <<-RUBY
         module Bukkits