Google Compute Engine offers scripts and daemons which run in the background and provides the following services: - Accounts daemon to setup and manage user accounts, and to enable SSH key based authentication. - Clock skew daemon to keep the system clock in sync after VM start and stop events. - Instance setup scripts to execute VM configuration scripts during boot. - IP forwarding daemon that integrates network load balancing with forwarding rule changes into the guest. - Metadata scripts to run user provided scripts at VM startup and shutdown. - Network setup service to enable multiple network interfaces on boot. WWW: https://github.com/GoogleCloudPlatform/compute-image-packages