Add JSON support to health controller

The health controller now responds to JSON requests, providing a structured response with status and timestamp information. This enhancement facilitates easier integration with monitoring tools and load balancers.
Additionally, tests have been added to verify the JSON responses for both success and error scenarios.

Author: JuanVqz

actionpack/CHANGELOG.md

@@ -1,6 +1,18 @@
-*   Add `render json` into `HealthController`.
+*   Add JSON support to the built-in health controller.
 
-    *Francesco Loreti*
+    The health controller now responds to JSON requests with a structured response
+    containing status and timestamp information. This makes it easier for monitoring
+    tools and load balancers to consume health check data programmatically.
+
+    ```ruby
+    # /up.json
+    {
+      "status": "up",
+      "timestamp": "2025-09-19T12:00:00Z"
+    }
+    ```
+
+    *Francesco Loreti*, *Juan Vásquez*
 
 *   Allow to open source file with a crash from the browser.
 

railties/lib/rails/health_controller.rb

@@ -44,15 +44,15 @@ def show
     private
       def render_up
         respond_to do |format|
-          format.html { render html: html_status(color: "green"), status: 200 }
-          format.json { render json: { status: 200 }, status: 200 }
+          format.html { render html: html_status(color: "green") }
+          format.json { render json: { status: "up", timestamp: Time.current.iso8601 } }
         end
       end
 
       def render_down
         respond_to do |format|
           format.html { render html: html_status(color: "red"), status: 500 }
-          format.json { render json: { status: 500 }, status: 500 }
+          format.json { render json: { status: "down", timestamp: Time.current.iso8601 }, status: 500 }
         end
       end
 

railties/test/rails_health_controller_test.rb

@@ -18,12 +18,6 @@ def setup
     assert_match(/background-color: green/, @response.body)
   end
 
-  test "health controller returns JSON success response" do
-    get :show, format: :json
-    assert_response :success
-    assert_equal({ "status" => 200 }, JSON.parse(@response.body))
-  end
-
   test "health controller renders red internal server error page in HTML" do
     @controller.instance_eval do
       def render_up
@@ -35,14 +29,30 @@ def render_up
     assert_match(/background-color: red/, @response.body)
   end
 
-  test "health controller returns JSON internal server error response" do
+  test "health controller returns JSON success response" do
+    get :show, format: :json
+    assert_response :success
+    assert_includes @response.content_type, "application/json"
+
+    json_response = JSON.parse(@response.body)
+    assert_equal "up", json_response["status"]
+    assert_includes json_response, "timestamp"
+    assert_match(/\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/, json_response["timestamp"])
+  end
+
+  test "health controller returns JSON error response" do
     @controller.instance_eval do
       def render_up
         raise Exception, "some exception"
       end
     end
     get :show, format: :json
     assert_response :internal_server_error
-    assert_equal({ "status" => 500 }, JSON.parse(@response.body))
+    assert_includes @response.content_type, "application/json"
+
+    json_response = JSON.parse(@response.body)
+    assert_equal "down", json_response["status"]
+    assert_includes json_response, "timestamp"
+    assert_match(/\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/, json_response["timestamp"])
   end
 end