Retry and cancel endpoints send 204 json response. Request is made with type json

app/assets/javascripts/pipelines/services/pipelines_service.js

@@ -40,6 +40,6 @@ export default class PipelinesService {
    * @return {Promise}
    */
   postAction(endpoint) {
-    return Vue.http.post(endpoint, {}, { emulateJSON: true });
+    return Vue.http.post(`${endpoint}.json`);
   }
 }

app/controllers/projects/pipelines_controller.rb

@@ -92,15 +92,31 @@ class Projects::PipelinesController < Projects::ApplicationController
   def retry
     pipeline.retry_failed(current_user)
 
+    respond_to do |format|
+      format.html do
         redirect_back_or_default default: namespace_project_pipelines_path(project.namespace, project)
       end
 
+      format.json do
+        render status: 204
+      end
+    end
+  end
+
   def cancel
     pipeline.cancel_running
 
+    respond_to do |format|
+      format.html do
         redirect_back_or_default default: namespace_project_pipelines_path(project.namespace, project)
       end
 
+      format.json do
+        render status: 204
+      end
+    end
+  end
+
   def charts
     @charts = {}
     @charts[:week] = Ci::Charts::WeekChart.new(project)