I've been developing for a while with a simple Dockerfile in the root of a given project's output... from there I rarely care about it.. in dev, I can mount the app path to the container for dev, and use environment variables set for any other services that are needed. I'm much more productive with Docker for (Windows|Mac) than I've ever been with the likes of vagrant, or whatever bastion of technology that manages VMs... I don't have to think of the VMs, that's generally IT/Infrastructure/DevOps job. yeah, sometimes I wear that hat, but not when I'm coding.

It is helped if the second layer further automates deployment. I would imagine Netflix is better at understanding its velocity than we are.

Yep but Netflix also has a decade of large scale arch wielded to AWS that we don't.

They might not be deploying containers on VMs on bare metal because they want to, but because they /have/ to.

Mind quantifying this overhead you assume containers-on-metal vs VMs will solve?

It's not assumed, it's widely known VMs have poor IO performance, that one of the main points for containers in the first place. Short ver: GIYF.

If you can't provide numbers, then please talk about what technologies you're assuming are involved that create this overhead.