Make host_meta/webfinger replies cacheable (fixes #6100) (#6101)

* Make host_meta/webfinger replies cacheable (fixes #6100)

Drop common code for handling users and sessions as webfinger queries
are very basic, public APIs.

Also explicitly mark results as cacheable with “expires_in”.

* Add “Vary: Accept” header for caching since content-negociation is used

1 files changed, 5 insertions, 1 deletions

diff --git a/app/controllers/well_known/webfinger_controller.rb b/app/controllers/well_known/webfinger_controller.rb
index 5cc606808..28654b61d 100644
--- a/app/controllers/well_known/webfinger_controller.rb
+++ b/app/controllers/well_known/webfinger_controller.rb
@@ -1,9 +1,11 @@
 # frozen_string_literal: true
 
 module WellKnown
-  class WebfingerController < ApplicationController
+  class WebfingerController < ActionController::Base
     include RoutingHelper
 
+    before_action { response.headers['Vary'] = 'Accept' }
+
     def show
       @account = Account.find_local!(username_from_resource)
 
@@ -16,6 +18,8 @@ module WellKnown
           render content_type: 'application/xrd+xml'
         end
       end
+
+      expires_in(3.days, public: true)
     rescue ActiveRecord::RecordNotFound
       head 404
     end