Hands-On Microservices with Kubernetes

Kubernetes and VMs

Kubernetes started as an orchestration platform for Docker containers. A lot of Docker-specific assumptions were built in. Kubernetes 1.3 added special support for CoreOS rkt and started the journey toward a decoupled runtime experience. Kubernetes 1.5 introduced the CRI, where the kubelet talks to the container runtime engine via gRPC. The CRI graduated to stable in Kubernetes 1.6.

As I mentioned earlier when discussing the abstraction of the container runtime, the CRI opened the door to multiple runtime implementations. One class of runtime extensions are lightweight or micro VMs. This may seem a little counter-productive because one of the biggest motivations for the container movement was that VMs are too heavyweight ...