Add admin notifications for new Mastodon versions (#26582)

app/models/software_update.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: software_updates
+#
+#  id            :bigint(8)        not null, primary key
+#  version       :string           not null
+#  urgent        :boolean          default(FALSE), not null
+#  type          :integer          default("patch"), not null
+#  release_notes :string           default(""), not null
+#  created_at    :datetime         not null
+#  updated_at    :datetime         not null
+#
+
+class SoftwareUpdate < ApplicationRecord
+  self.inheritance_column = nil
+
+  enum type: { patch: 0, minor: 1, major: 2 }, _suffix: :type
+
+  def gem_version
+    Gem::Version.new(version)
+  end
+
+  class << self
+    def check_enabled?
+      ENV['UPDATE_CHECK_URL'] != ''
+    end
+
+    def pending_to_a
+      return [] unless check_enabled?
+
+      all.to_a.filter { |update| update.gem_version > Mastodon::Version.gem_version }
+    end
+
+    def urgent_pending?
+      pending_to_a.any?(&:urgent?)
+    end
+  end
+end

app/models/user_settings.rb

@@ -44,6 +44,7 @@ class UserSettings
     setting :pending_account, default: true
     setting :trends, default: true
     setting :appeal, default: true
+    setting :software_updates, default: 'critical', in: %w(none critical patch all)
   end
 
   namespace :interactions do