The "process sandbox" wars are over. Everybody lost, hypervisors won. That's it. It feels incredibly wasteful after all. Hypervisors don't share mm, scheduler, etc. It's a lot of wasted resources. Google came in with gvisor at the last minute to try to say "no, sandboxes aren't dead. Look at our approach with gvisor". They lost too and are now moving away from it.
Can't help but feel the security concerns are overblown. To support my claim; Well, Google IS using gvisor as part of their GKE sandboxing security..
https://cloud.google.com/blog/products/serverless/cloud-run-...
But at the end of the day, there is a line in the sand around hypervisors vs proc/kernel isolation models. I challenge you to go to a financial or medical institute and tell their CTO "yeah, we have this super bullet proof shared-kernel-inproc isolation model"
The first question you'd get is "Why is this not just part of upstream linux?" Answer that question and realize why you should just use a hypervisor.
https://cloud.google.com/blog/products/serverless/cloud-run-...
Obviously there might be many reasons for that, but as someone who worked on a similar gvisor tech for another company, it's dead in the water. No security expert or consultant will ever sign off on a process isolation model. Despite of architecture, audits, reviews, etc. There is just too much surface area for anyone to feel comfortable signing off on hostile multi-tenants with process isolation regardless of the sandboxing tech.
Not saying that there are no bugs in hypervisors, but the surface area is so so much smaller.
Disclaimer: I work on this product but wasn't involved in this decision.
I've been wondering about this - are they really?
Now if workloads become less ephemeral and more general purpose, tolerance for startup latency goes up, annd probability of bespoke needs goes up making VM more palatable.