Rebuild AMI using SSM Automation

In the previous post I used Packer to remove block device mappings from Ubuntu AMI to ensure EC2 auto-recovery is working. While Packer is a fantastic tool with many features, it is synchronous in its nature and requires active SSH connection to the temporary instance in order to bake new AMI.

Can we get similar results with AWS tools alone? Indeed, we can!

In December of 2016, at the re:Invent, AWS announced a slew of interesting new features for their Amazon EC2 Systems Manager (a.k.a. SSM). The initial documentation and tutorials were sparse, so their capabilities weren't immediately clear. One of these new features, Automation, offers functionality similar to Packer, so I decided to learn more about it by applying to my simple use case.

Ensure EC2 auto-recovery by rebuilding AMI with Packer

Problem: Amazon EC2 auto recovery fails if machine image has ephemeral block device mappings defined (even when no instance store volumes are attached).

Solutions:

1. Specify custom block device mapping during instance launch.
2. Rebuild Ubuntu AMI (with automation).

This post shows how to achieve the later using Packer by HashiCorp.