Cloud-init is the industry standard multi-distribution method for
 cross-platform cloud instance initialization. It is supported across all major
 public cloud providers, provisioning systems for private cloud infrastructure,
 and bare-metal installations.
 .
 Cloud instances are initialized from a disk image and instance data:
 .
  * Cloud metadata
  * User data (optional)
  * Vendor data (optional)
 .
 Cloud-init will identify the cloud it is running on during boot, read any
 provided metadata from the cloud and initialize the system accordingly. This
 may involve setting up the network and storage devices to configuring SSH
 access key and many other aspects of a system. Later on the cloud-init will
 also parse and process any optional user or vendor data that was passed to
 the instance.