set vary header and cache documentation

lib/travis/api/app/endpoint/documentation.rb

@@ -4,7 +4,7 @@ class Travis::Api::App
   class Endpoint
     # Generated API documentation.
     class Documentation < Endpoint
-      set prefix: '/docs', public_folder: File.expand_path('../documentation', __FILE__)
+      set prefix: '/docs', public_folder: File.expand_path('../documentation', __FILE__), static_cache_control: :public
       enable :inline_templates, :static
 
       # Don't cache general docs in development
@@ -12,6 +12,7 @@ class Travis::Api::App
 
       # HTML view for [/endpoints](#/endpoints/).
       get '/' do
+        cache_control :public
         content_type :html
         endpoints = Endpoints.endpoints
         erb :index, {}, endpoints: endpoints.keys.sort.map { |k| endpoints[k] }

lib/travis/api/app/extensions/scoping.rb

@@ -33,6 +33,9 @@ class Travis::Api::App
           headers['X-Accepted-OAuth-Scopes'] = name.to_s
 
           if scopes.include? name
+            headers['Vary'] = 'Accept'
+            headers['Vary'] << ', Authorization' if scope == :public
+            #cache_control :public, :must_revalidate if request.head? or request.get?
             true
           elsif logged_in?
             halt 403, "insufficient access"