From the article "Turns out, the corrupted file caused the BinaryPack serialization library to immediately execute itself with a stack overflow exception, bypassing any exception handling and just exiting the process. Within minutes, our global DNS server fleet of close to a 100 servers was practically dead." and from your comment "We do the same for the CDN and always use canary testing if possible. We unfortunately never assumed this piece of software could cause all the DNS servers to stack overflow."
This read like the DNS software is being changed. As some people already mentioned is this a corruption where checksum would of been prevented the stack overflow or would a canary detected this? Why would a change to DNS server software not canaried?
Have you looked at Cuelang [1] as a configuration language or source of truth?. It's still new but it's a superset of JSON but attempted to combine data/schema into one and reject inheritance and replace with validation instead.
XDP UDP mapping to firecracker vms via WireGuard is really interesting! I have a question a bit before UDP is landed on the NIC, assuming the NICs on the edge servers is connected to multiple transit providers for incoming and outgoing traffic. This mean from the VM perspective, you can have incoming/outgoing tap/tun inside the VMs able to receive packets from difference transits or outbound, did you do anything with this aspect? and if so do you also deal with ECMP inbound in such that you can have the same virtual IP receiving UDP on multiple edge servers?