Support immutable directive in Cache-Control

Author: heka1024

actionpack/CHANGELOG.md

@@ -1,3 +1,12 @@
+*   Support `immutable` directive in Cache-Control
+
+    ```ruby
+    expires_in 1.minute, public: true, immutable: true
+    # Cache-Control: public, max-age=60, immutable
+    ```
+
+    *heka1024*
+
 *   Add `:wasm_unsafe_eval` mapping for `content_security_policy`
 
     ```ruby

actionpack/lib/action_controller/metal/conditional_get.rb

@@ -293,6 +293,7 @@ def expires_in(seconds, options = {})
         must_revalidate: options.delete(:must_revalidate),
         stale_while_revalidate: options.delete(:stale_while_revalidate),
         stale_if_error: options.delete(:stale_if_error),
+        immutable: options.delete(:immutable),
       )
       options.delete(:private)
 

actionpack/lib/action_dispatch/http/cache.rb

@@ -171,6 +171,7 @@ def prepare_cache_control!
         PUBLIC                = "public"
         PRIVATE               = "private"
         MUST_REVALIDATE       = "must-revalidate"
+        IMMUTABLE             = "immutable"
 
         def handle_conditional_get!
           # Normally default cache control setting is handled by ETag middleware. But, if
@@ -221,6 +222,7 @@ def merge_and_normalize_cache_control!(cache_control)
             options << MUST_REVALIDATE if control[:must_revalidate]
             options << "stale-while-revalidate=#{stale_while_revalidate.to_i}" if stale_while_revalidate
             options << "stale-if-error=#{stale_if_error.to_i}" if stale_if_error
+            options << IMMUTABLE if control[:immutable]
             options.concat(extras) if extras
           end
 

actionpack/test/controller/render_test.rb

@@ -179,6 +179,11 @@ def conditional_hello_with_expires_in_with_stale_if_error
     render action: "hello_world"
   end
 
+  def conditional_hello_with_expires_in_with_immutable
+    expires_in 1.minute, public: true, immutable: true
+    render action: "hello_world"
+  end
+
   def conditional_hello_with_expires_in_with_public_with_more_keys
     expires_in 1.minute, :public => true, "s-maxage" => 5.hours
     render action: "hello_world"
@@ -442,6 +447,11 @@ def test_expires_in_header_with_stale_if_error
     assert_equal "max-age=60, public, stale-if-error=300", @response.headers["Cache-Control"]
   end
 
+  def test_expires_in_header_with_immutable
+    get :conditional_hello_with_expires_in_with_immutable
+    assert_equal "max-age=60, public, immutable", @response.headers["Cache-Control"]
+  end
+
   def test_expires_in_header_with_additional_headers
     get :conditional_hello_with_expires_in_with_public_with_more_keys
     assert_equal "max-age=60, public, s-maxage=18000", @response.headers["Cache-Control"]