The EC2 create-image API/command/console action is a convenient trigger to create an AMI from a running (or stopped) EBS boot instance. It takes a snapshot of the instance’s EBS volume(s) and registers the snapshot as an AMI. New instances can be run of this AMI with their starting state almost identical to the original running instance.
For years, I’ve been propagating the belief that a create-image call against a running instance is equivalent to these steps:
stopregister-imagestart
However, through experimentation I’ve found that though create-image is similar to the above, it doesn’t have all of the effects that a stop/start has on an instance.
Specifically, when you trigger create-image,
-
the Elastic IP address is not disassociated, even if the instance is not in a VPC,
-
the Internal IP address is preserved, and
-
the ephemeral storage (often on
/mnt) is not lost.
I have not tested it, but I suspect that a new billing hour is not started with create-image (as it would be with a stop/start).
So, I am now going to start saying that create-image is equivalent to: