Add Mastodon service page

app/controllers/services/mastodon_controller.rb

@@ -0,0 +1,14 @@
+class Services::MastodonController < Services::BaseController
+  before_action :authenticate_user!
+  before_action :require_service_available
+
+  def show
+    @service_enabled = current_user.services_enabled.include?(:mastodon)
+  end
+
+  private
+
+    def require_service_available
+      http_status :not_found unless Setting.ejabberd_enabled?
+    end
+end