1 files changed, 43 insertions, 2 deletions
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 879a1ea89f..fd747c1686 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -62,7 +62,7 @@ These configuration methods are to be called on a `Rails::Railtie` object, such
 
 * `config.autoload_once_paths` accepts an array of paths from which Rails will autoload constants that won't be wiped per request. Relevant if `config.cache_classes` is `false`, which is the case in development mode by default. Otherwise, all autoloading happens only once. All elements of this array must also be in `autoload_paths`. Default is an empty array.
 
-* `config.autoload_paths` accepts an array of paths from which Rails will autoload constants. Default is all directories under `app`.
+* `config.autoload_paths` accepts an array of paths from which Rails will autoload constants. Default is all directories under `app`. It is no longer recommended to adjust this. See [Autoloading and Reloading Constants](autoloading_and_reloading_constants.html#autoload-paths-and-eager-load-paths)
 
 * `config.cache_classes` controls whether or not application classes and modules should be reloaded on each request. Defaults to `false` in development mode, and `true` in test and production modes.
 
@@ -200,6 +200,7 @@ The full set of methods that can be used in this block are as follows:
 * `force_plural` allows pluralized model names. Defaults to `false`.
 * `helper` defines whether or not to generate helpers. Defaults to `true`.
 * `integration_tool` defines which integration tool to use to generate integration tests. Defaults to `:test_unit`.
+* `system_tests` defines which integration tool to use to generate system tests. Defaults to `:test_unit`.
 * `javascripts` turns on the hook for JavaScript files in generators. Used in Rails for when the `scaffold` generator is run. Defaults to `true`.
 * `javascript_engine` configures the engine to be used (for eg. coffee) when generating assets. Defaults to `:js`.
 * `orm` defines which orm to use. Defaults to `false` and will use Active Record by default.
@@ -461,7 +462,10 @@ The schema dumper adds one additional configuration option:
     config.action_dispatch.default_headers = {
       'X-Frame-Options' => 'SAMEORIGIN',
       'X-XSS-Protection' => '1; mode=block',
-      'X-Content-Type-Options' => 'nosniff'
+      'X-Content-Type-Options' => 'nosniff',
+      'X-Download-Options' => 'noopen',
+      'X-Permitted-Cross-Domain-Policies' => 'none',
+      'Referrer-Policy' => 'strict-origin-when-cross-origin'
     }
     ```
 
@@ -737,6 +741,8 @@ There are a few configuration options available in Active Support:
 
 * `config.active_job.logger` accepts a logger conforming to the interface of Log4r or the default Ruby Logger class, which is then used to log information from Active Job. You can retrieve this logger by calling `logger` on either an Active Job class or an Active Job instance. Set to `nil` to disable logging.
 
+* `config.active_job.custom_serializers` allows to set custom argument serializers. Defaults to `[]`.
+
 ### Configuring Action Cable
 
 * `config.action_cable.url` accepts a string for the URL for where
@@ -748,6 +754,41 @@ main application.
 You can set this as nil to not mount Action Cable as part of your
 normal Rails server.
 
+
+### Configuring Active Storage
+
+`config.active_storage` provides the following configuration options:
+
+* `config.active_storage.analyzers` accepts an array of classes indicating the analyzers available for Active Storage blobs. The default is `[ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer]`. The former can extract width and height of an image blob; the latter can extract width, height, duration, angle, and aspect ratio of a video blob.
+
+* `config.active_storage.previewers` accepts an array of classes indicating the image previewers available in Active Storage blobs. The default is `[ActiveStorage::Previewer::PDFPreviewer, ActiveStorage::Previewer::VideoPreviewer]`. The former can generate a thumbnail from the first page of a PDF blob; the latter from the relevant frame of a video blob.
+
+* `config.active_storage.paths` accepts a hash of options indicating the locations of previewer/analyzer commands. The default is `{}`, meaning the commands will be looked for in the default path. Can include any of these options:
+    * `:ffprobe` - The location of the ffprobe executable.
+    * `:mutool` - The location of the mutool executable.
+    * `:ffmpeg` - The location of the ffmpeg executable.
+
+   ```ruby
+   config.active_storage.paths[:ffprobe] = '/usr/local/bin/ffprobe'
+   ```
+
+* `config.active_storage.variable_content_types` accepts an array of strings indicating the content types that Active Storage can transform through ImageMagick. The default is `%w(image/png image/gif image/jpg image/jpeg image/vnd.adobe.photoshop)`.
+
+* `config.active_storage.content_types_to_serve_as_binary` accepts an array of strings indicating the content types that Active Storage will always serve as an attachment, rather than inline. The default is `%w(text/html
+text/javascript image/svg+xml application/postscript application/x-shockwave-flash text/xml application/xml application/xhtml+xml)`.
+
+* `config.active_storage.queue` can be used to set the name of the Active Job queue used to perform jobs like analyzing the content of a blob or purging a blog.
+
+  ```ruby
+  config.active_job.queue = :low_priority
+  ```
+
+* `config.active_storage.logger` can be used to set the logger used by Active Storage. Accepts a logger conforming to the interface of Log4r or the default Ruby Logger class.
+
+  ```ruby
+  config.active_job.logger = ActiveSupport::Logger.new(STDOUT)
+  ```
+
 ### Configuring a Database
 
 Just about every Rails application will interact with a database. You can connect to the database by setting an environment variable `ENV['DATABASE_URL']` or by using a configuration file called `config/database.yml`.