[fhuici]

At least for cloud deployments you'll (for almost all cases) already have a hypervisor underneath to provide strong isolation. With that in place, ideally you'd run your application (ultimately the only thing you care about) as close to that hypervisor as possible. Instead, we have hypervisor, and then inside the VM the (say Linux) kernel, user-space, the container runtime, and finally the application.

With a unikernel the stack becomes hypervisor and a VM that has a very thin layer and then the application -- as close to the application running on the hypervisor as possible. This results in lots of gains in terms of minimal cold boot times, memory usage, server density (thousands on a single server), etc.

In fact, you don't need to see containers and unikernels as an either or choice: in fact, at Unikraft (another unikernel project) for development and local deployment we have support for Docker/Dockerfiles -- and then for deployment we provide a lean unikernel as described above.

Hope this clarifies things somewhat.