Revert Amazon EC2 instance to snapshot?

Question

Is there a convenient way to roll-back an EC2 instance to a previously saved snapshot in the same manner that you can do so with VMWare and other virtualisation platforms. In my investigations so far, it seems you have to deploy a new instance and select the snapshot as the starting volume.

I am doing a lot of testing with new EC2 instance initialisation scripts at present, and having to configure and deploy a new instance for every test is tedious and costly. If I can roll-back to a snapshot of the initial state of the system quickly, this would save a lot of time and effort.

Answer 1

The answers by John and Stefan are both correct. There's no way to trigger a simple "Roll this EC2 instance back to an earlier snapshot" feature on AWS.

There is a way to "roll back" an instance's filesystem to a snapshot by restoring the snapshot to a new EBS volume, detaching and deleting the old one, and attaching the new one.

And, of course, AWS is eminently automatable. You could definitely write your own automation to make that happen.

Having said all of that, if you're trying to test instance creation scripts, I have to agree with John, tearing down and rebuilding the instance is the most reliable way to make sure you're testing it accurately, and shouldn't really be more costly than restoring to a snapshot.

The other path you might consider, particularly if you want the instance to start in a known state that doesn't match a particular predefined AMI, is to build an AMI of your own (e.g. w/ Packer) and use that as the basis for your test. Then instead of restoring to a snapshot, you're creating a new instance from an AMI you've prepared.