FWIW, the stock kernel (and HWE/HWE-edge kernels) recently picked up current ENA drivers. ixgbevf, unfortunately, doesn't look like it's been updated in-tree so it still lags behind Amazon's recommendation (currently 2.14.2, whereas Xenial's in-tree driver claims to be 2.12.1 and Trusty has 2.11.3).
Is this used by vanilla docker / ECS, or just k8s?
that advice holds regardless what software you're using, so long as the software does network traffic.
It holds for just running plain old nginx websites.
It doesn't really matter for small instance sizes where your networking is already rate-limited by amazon so much that ENA drivers won't matter, but on beefy instances it's always good advice to make sure you're using ENA supported driverse.
See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced...
https://github.com/kubernetes/kops/issues/1558
Missing ENA and ixgbevf can be a real performance killer!