Say goodbye to virtualization for a safer cloud

When it comes to isolation on the cloud, conventional wisdom holds that virtual machines (VMs) provide greater isolation than containers because of their low-level interface to the host. A lower-level interface reduces the amount of code and complexity needed in the kernel that must be relied upon for isolation. However, it is incorrectly assumed that virtualization mechanisms are required to achieve a low-level interface suitable for isolation. In this paper, we argue that the interface to the host can be lowered for any application by moving kernel components to userspace. We show that using a userspace network stack results in a 33% reduction in kernel code usage, which is 20% better than when resorting to virtualization mechanisms and using a VM.