Refactor Cache-Control and Vary definitions (#24347)

app/controllers/activitypub/base_controller.rb

@@ -7,10 +7,6 @@ class ActivityPub::BaseController < Api::BaseController
 
   private
 
-  def set_cache_headers
-    response.headers['Vary'] = 'Signature' if authorized_fetch_mode?
-  end
-
   def skip_temporary_suspension_response?
     false
   end

app/controllers/activitypub/collections_controller.rb

@@ -4,11 +4,12 @@ class ActivityPub::CollectionsController < ActivityPub::BaseController
   include SignatureVerification
   include AccountOwnedConcern
 
+  vary_by -> { 'Signature' if authorized_fetch_mode? }
+
   before_action :require_account_signature!, if: :authorized_fetch_mode?
   before_action :set_items
   before_action :set_size
   before_action :set_type
-  before_action :set_cache_headers
 
   def show
     expires_in 3.minutes, public: public_fetch_mode?

app/controllers/activitypub/followers_synchronizations_controller.rb

@@ -4,9 +4,10 @@ class ActivityPub::FollowersSynchronizationsController < ActivityPub::BaseContro
   include SignatureVerification
   include AccountOwnedConcern
 
+  vary_by -> { 'Signature' if authorized_fetch_mode? }
+
   before_action :require_account_signature!
   before_action :set_items
-  before_action :set_cache_headers
 
   def show
     expires_in 0, public: false

app/controllers/activitypub/outboxes_controller.rb

@@ -6,9 +6,10 @@ class ActivityPub::OutboxesController < ActivityPub::BaseController
   include SignatureVerification
   include AccountOwnedConcern
 
+  vary_by -> { 'Signature' if authorized_fetch_mode? || page_requested? }
+
   before_action :require_account_signature!, if: :authorized_fetch_mode?
   before_action :set_statuses
-  before_action :set_cache_headers
 
   def show
     if page_requested?
@@ -16,6 +17,7 @@ class ActivityPub::OutboxesController < ActivityPub::BaseController
     else
       expires_in(3.minutes, public: public_fetch_mode?)
     end
+
     render json: outbox_presenter, serializer: ActivityPub::OutboxSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
   end
 
@@ -80,8 +82,4 @@ class ActivityPub::OutboxesController < ActivityPub::BaseController
   def set_account
     @account = params[:account_username].present? ? Account.find_local!(username_param) : Account.representative
   end
-
-  def set_cache_headers
-    response.headers['Vary'] = 'Signature' if authorized_fetch_mode? || page_requested?
-  end
 end

app/controllers/activitypub/replies_controller.rb

@@ -7,9 +7,10 @@ class ActivityPub::RepliesController < ActivityPub::BaseController
 
   DESCENDANTS_LIMIT = 60
 
+  vary_by -> { 'Signature' if authorized_fetch_mode? }
+
   before_action :require_account_signature!, if: :authorized_fetch_mode?
   before_action :set_status
-  before_action :set_cache_headers
   before_action :set_replies
 
   def index