I am working on https://github.com/isola-run/isola which uses gVisor (not firecracker) on k8s (or something like kind, locally). Includes snapshotting, network controls and everything. Hope you could find this useful
I'm working on Isola (https://github.com/isola-run/isola), a passion project of mine. It allows you to easily create and control sandboxes for executing untrusted code on any Kubernetes cluster (one helm install). To support some features I wanted (like on demand snapshotting of specific containers' filesystem in a sandbox pod or limiting egress rate from the sandbox I am working on now) I contributed some changes to gVisor. Happy to chat about the design and implementation of such a project if anyone interested!
Funny, I had a similar experience TAing “Intro to CS” (first semester C programming course). The student was certain he encountered a compiler bug (pushing back on my assumption there was something wrong with their code, since while compilers do have bugs, they are probably not in the code generation of a nested for loop). After spending a few minutes parsing their totally unindented code, the off-by-one error revealed itself