There's a Github Pages FAQ describing why it was made and how it fits with other solutions: https://firecracker-microvm.github.io/
and a high-level design document about how it works https://github.com/firecracker-microvm/firecracker/blob/mast...
and a high-level design document about how it works https://github.com/firecracker-microvm/firecracker/blob/mast...