After creating an AMI, how do I launch it using the same configuration?

Question

I set up my instance to my liking, created an image (AMI) from it, and stopped the instance. I now want to change the AMI for that instance to the new AMI, and re-launch the instance. How do I do this?

To clarify, clicking "Launch" from the list of AMIs in the management console is not what I need. This creates a new instance, making me go through the wizard again when I just want the same configuration, and it gives the new instance a different IP address, and so on.

Answer 1

I think you have a misunderstanding of how AMIs work. An AMI is just a template for launching an instance with a particular configuration.

You created your original instance from (presumably) a bare bones distribution AMI (say ami-11111), modified it, and created your own AMI (say ami-22222).

You can now launch instances using ami-22222 that will be configured the way you want, but it no longer has any connection to ami-11111. It doesn't make any sense to "change the AMI [...] to the new AMI".

If you stop an instance it will always get a new IP address when it is restarted. You can get a persistent IP address by:

• Allocating an Elastic IP.
• Launching the instance you want (in this case ami-22222)
• Assigning the Elastic IP to that instance.

The instance will then be accessible via the Elastic IP address.

If you modify the instance in the future and create a new image of it (say, ami-33333), you can:

• Launch an instance based on ami-33333.
• Assign your Elastic IP to ami-33333 (thereby disconnecting ami-22222 from that IP).
• Terminate ami-22222 once the new instance is active.

Note that it can take a minute or so for the transition to the new AMI during which the server will be unresponsive.

Answer 2

You can't change an existing instance to a new ami, instead you launch a new instance from that ami. When you launch an instance, it creates a copy of the ami in whatever storage type you are using (instance or ebs).