[Snaps] Full snapshot + restore

[raduweiss]

The ability to create a microVM snapshot is compelling for serverless use cases. It’s also a feature ask from users. We’ve been tinkering with a Firecracker prototype that has a variant of snapshot + restore functionality. We aimed to optimize the speed of these operations.

This item tracks the capability of creating full snapshots (entire microVM memory), and the capability of restoring microVM execution from a full snapshot.

Related issues: #1035, #886

[s3rj1k]

Great news everyone ;) Would be nice to have non-blocking snapshots, just like qemu does using image backing files, redirecting new writes to top image, than snapshoting backing image (RO one), and then merging back changes.

[luminitavoicu]

We released full snapshot functionality as dev-preview in Firecracker v0.23. Closing this.

[JonathanWoollett-Light]

Still in developer preview, re-opening to indicate this.

We will move to shipped synchronously with related snapshot functionality (https://github.com/firecracker-microvm/firecracker/issues/2142, https://github.com/firecracker-microvm/firecracker/issues/2476).