FIX: properly specify default on no cache on all resources

app/controllers/application_controller.rb

@@ -45,6 +45,7 @@ class ApplicationController < ActionController::Base
   before_filter :check_xhr
   after_filter  :add_readonly_header
   after_filter  :perform_refresh_session
+  after_filter  :dont_cache_page
 
   layout :set_layout
 
@@ -64,6 +65,12 @@ class ApplicationController < ActionController::Base
     refresh_session(current_user)
   end
 
+  def dont_cache_page
+    if !response.headers["Cache-Control"] && response.cache_control.blank?
+      response.headers["Cache-Control"] = "no-store, must-revalidate, no-cache, private"
+    end
+  end
+
   def slow_platform?
     request.user_agent =~ /Android/
   end

spec/controllers/topics_controller_spec.rb

@@ -529,6 +529,7 @@ describe TopicsController do
       get :show, topic_id: topic.id, slug: topic.slug
       expect(response).to be_success
       expect(css_select("link[rel=canonical]").length).to eq(1)
+      expect(response.headers["Cache-Control"]).to eq("no-store, must-revalidate, no-cache, private")
     end
   end
 

spec/controllers/user_avatars_controller_spec.rb

@@ -46,6 +46,7 @@ describe UserAvatarsController do
 
       get :show, size: 98, username: user.username, version: upload.id, hostname: 'default'
       expect(response.body).to eq("image")
+      expect(response.headers["Cache-Control"]).to eq('max-age=31557600, public')
     end
 
     it 'serves image even if size missing and its in local mode' do