Can you achieve "eventual" ami upgrades?

[kncesarini]

The behavior i would like to see when upgrading AMIs (lets say we're going from bottlerocket 1.45 to 1.49) is that existing nodes can continue on their existing AMIs until their lifetime expires (we do max 2 weeks), while new nodes will use the latest configured AMI. Currently, the behavior is that after upgrading the amiSelectorTerms, all nodes are marked as drifted (and replaced as soon as possible according to disruption rules).

  amiSelectorTerms:
    - alias: [email protected]

Is there any way to achieve this in a "simple" way? Ideally it would just be something like this (which doesn't work as you can't have multiple alias)

  amiSelectorTerms:
    - alias: [email protected]
    - alias: [email protected]

[jmdeal]

Do you not want drift in general, or specifically for AMIs? If you're fine with disabling drift altogether you can disable it using disruption budgets on a per-NodePool basis. I'd be interested to understand your requirement though - generally it's better to let drift disrupt nodes than expiration since it can be controlled by disruption budgets. This results in a more gradual disruption whereas relying on expiration can result in "waves" of disruption activity.