+1 on smolvm! I provision a smolvm per job in preloop, a local/self-hosted github actions( https://github.com/preloopdev/preloop).
iirc there was also some work to add a deny-cidr option as well which would give you more flexibility. But the egress filter captures most of what you need so it works great nonetheless.
replylove seeing preloop's work :)
replyhow does it do it?
replyproxy in the middle (but cert pinning problems)
or DNS filtering? (but agent could have "memorized" stable IP)
Cert pinning: not a problem. we don't decrypt traffic, we just pass it through. The only exception is hosts you give a credential to, since we have to insert the key.
replyMemorized IP: doesn't work, the vm can only connect to an IP if it came from a DNS lookup of an allowed name. Any other IP is blocked.
A bit of "shared responsibility" philosophy kicking through but I try to have good defaults