1 files changed, 87 insertions, 1 deletions
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index ca5623bf73..2f0f3573fb 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -27,6 +27,31 @@ Upgrading from Rails 4.0 to Rails 4.1
 
 NOTE: This section is a work in progress.
 
+### CSRF protection from remote `<script>` tags
+
+Or, "whaaat my tests are failing!!!?"
+
+Cross-site request forgery (CSRF) protection now covers GET requests with
+JavaScript responses, too. That prevents a third-party site from referencing
+your JavaScript URL and attempting to run it to extract sensitive data.
+
+This means that your functional and integration tests that use
+
+```ruby
+get :index, format: :js
+```
+
+will now trigger CSRF protection. Switch to
+
+```ruby
+xhr :get, :index, format: :js
+```
+
+to explicitly test an XmlHttpRequest.
+
+If you really mean to load JavaScript from remote `<script>` tags, skip CSRF
+protection on that action.
+
 ### Spring
 
 If you want to use Spring as your application preloader you need to:
@@ -39,9 +64,36 @@ NOTE: User defined rake tasks will run in the `development` environment by
 default. If you want them to run in other environments consult the
 [Spring README](https://github.com/jonleighton/spring#rake).
 
+### `config/secrets.yml`
+
+If you want to use the new `secrets.yml` convention to store your application's
+secrets, you need to:
+
+1. Create a `secrets.yml` file in your `config` folder with the following content:
+
+    ```yaml
+    development:
+      secret_key_base:
+
+    test:
+      secret_key_base:
+
+    production:
+      secret_key_base:
+    ```
+
+2. Copy the existing `secret_key_base` from the `secret_token.rb` initializer to
+   `secrets.yml` under the `production` section.
+
+3. Remove the `secret_token.rb` initializer.
+
+4. Use `rake secret` to generate new keys for the `development` and `test` sections.
+
+5. Restart your server.
+
 ### Changes in JSON handling
 
-The are a few major changes related to JSON handling in Rails 4.1.
+There are a few major changes related to JSON handling in Rails 4.1.
 
 #### MultiJSON removal
 
@@ -156,6 +208,40 @@ end
 ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers
 ```
 
+### I18n enforcing available locales
+
+Rails 4.1 now defaults the I18n option `enforce_available_locales` to `true`,
+meaning that it will make sure that all locales passed to it must be declared in
+the `available_locales` list.
+
+To disable it (and allow I18n to accept *any* locale option) add the following
+configuration to your application:
+
+```ruby
+config.i18n.enforce_available_locales = false
+```
+
+Note that this option was added as a security measure, to ensure user input could
+not be used as locale information unless previously known, so it's recommended not
+to disable this option unless you have a strong reason for doing so.
+
+### Mutator methods called on Relation
+
+`Relation` no longer has mutator methods like `#map!` and `#delete_if`. Convert
+to an `Array` by calling `#to_a` before using these methods.
+
+It intends to prevent odd bugs and confusion in code that call mutator
+methods directly on the `Relation`.
+
+```ruby
+# Instead of this
+Author.where(name: 'Hank Moody').compact!
+
+# Now you have to do this
+authors = Author.where(name: 'Hank Moody').to_a
+authors.compact!
+```
+
 Upgrading from Rails 3.2 to Rails 4.0
 -------------------------------------