[wahnfrieden]

Since you're already using puppet, which is great at keeping existing instances up to date with config changes (it's almost the whole point), wouldn't it be better for your CI to create those AMIs asynchronously when you deploy, but not actually use them unless you (or autoscale) are launching new instances? Just use puppet to deploy config changes as usual, then have the AMIs at the ready, rather than immediately recycling your instances with the new AMIs. This should be much faster (and more loosely decoupled from AWS).