What Firecracker does
Firecracker uses the KVM feature of Linux to run each guest as a real virtual machine. It emulates only a few devices, so a microVM needs little memory and starts fast. AWS wrote it in Rust and publishes it under the Apache-2.0 license.
Why sandbox providers use it
Each sandbox gets its own guest kernel. Code in one sandbox cannot reach the kernel of another sandbox or of the host. Firecracker can also save a running microVM to disk and load it again, which is how some providers offer snapshots and pause and resume.
Referencefirecracker-microvm.github.io
