src/sys/pkg/bin/system-updater/sysmgr.config

{
  "startup_services": [
    "fuchsia.update.installer.Installer"
  ],
  "services": {
    "fuchsia.update.installer.Installer": "fuchsia-pkg://fuchsia.com/system-updater#meta/system-updater.cmx"
  }
}