MessageBus handles readonly redis now, no need to wrap it

config/initializers/04-discourse_bus.rb

@@ -1,3 +0,0 @@
-require_dependency 'discourse_bus'
-
-DiscourseBus.start!

config/initializers/04-message_bus.rb

@@ -0,0 +1,47 @@
+MessageBus.site_id_lookup do
+  RailsMultisite::ConnectionManagement.current_db
+end
+
+MessageBus.extra_response_headers_lookup do |env|
+  {
+    "Access-Control-Allow-Origin" => Discourse.base_url_no_prefix,
+    "Access-Control-Allow-Methods" => "GET, POST",
+    "Access-Control-Allow-Headers" => "X-SILENCE-LOGGER, X-Shared-Session-Key"
+  }
+end
+
+MessageBus.user_id_lookup do |env|
+  user = CurrentUser.lookup_from_env(env)
+  user.id if user
+end
+
+MessageBus.group_ids_lookup do |env|
+  user = CurrentUser.lookup_from_env(env)
+  user.groups.select('groups.id').map{|g| g.id} if user
+end
+
+MessageBus.on_connect do |site_id|
+  RailsMultisite::ConnectionManagement.establish_connection(db: site_id)
+end
+
+MessageBus.on_disconnect do |site_id|
+  ActiveRecord::Base.connection_handler.clear_active_connections!
+end
+
+# Point at our redis
+MessageBus.redis_config = YAML.load(ERB.new(File.new("#{Rails.root}/config/redis.yml").read).result)[Rails.env].symbolize_keys
+
+MessageBus.long_polling_enabled = SiteSetting.enable_long_polling
+MessageBus.long_polling_interval = SiteSetting.long_polling_interval
+
+MessageBus.is_admin_lookup do |env|
+  user = CurrentUser.lookup_from_env(env)
+  if user && user.admin
+    true
+  else
+    false
+  end
+end
+
+MessageBus.cache_assets = !Rails.env.development?
+MessageBus.enable_diagnostics