Add admin dashboard (#8029)

app/controllers/admin/dashboard_controller.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+require 'sidekiq/api'
+
+module Admin
+  class DashboardController < BaseController
+    def index
+      @users_count           = User.count
+      @registrations_week    = Redis.current.get("activity:accounts:local:#{current_week}") || 0
+      @logins_week           = Redis.current.pfcount("activity:logins:#{current_week}")
+      @interactions_week     = Redis.current.get("activity:interactions:#{current_week}") || 0
+      @relay_enabled         = Relay.enabled.exists?
+      @single_user_mode      = Rails.configuration.x.single_user_mode
+      @registrations_enabled = Setting.open_registrations
+      @deletions_enabled     = Setting.open_deletions
+      @invites_enabled       = Setting.min_invite_role == 'user'
+      @search_enabled        = Chewy.enabled?
+      @version               = Mastodon::Version.to_s
+      @database_version      = ActiveRecord::Base.connection.execute('SELECT VERSION()').first['version'].match(/\A(?:PostgreSQL |)([^\s]+).*\z/)[1]
+      @redis_version         = redis_info['redis_version']
+      @reports_count         = Report.unresolved.count
+      @queue_backlog         = Sidekiq::Stats.new.enqueued
+      @recent_users          = User.confirmed.recent.includes(:account).limit(4)
+      @database_size         = ActiveRecord::Base.connection.execute('SELECT pg_database_size(current_database())').first['pg_database_size']
+      @redis_size            = redis_info['used_memory']
+      @ldap_enabled          = ENV['LDAP_ENABLED'] == 'true'
+      @cas_enabled           = ENV['CAS_ENABLED'] == 'true'
+      @saml_enabled          = ENV['SAML_ENABLED'] == 'true'
+      @pam_enabled           = ENV['PAM_ENABLED'] == 'true'
+      @hidden_service        = ENV['ALLOW_ACCESS_TO_HIDDEN_SERVICE'] == 'true'
+    end
+
+    private
+
+    def current_week
+      @current_week ||= Time.now.utc.to_date.cweek
+    end
+
+    def redis_info
+      @redis_info ||= Redis.current.info
+    end
+  end
+end