Booting an Ubuntu LTS cloud-init QEMU VM inside a Proxmox VM

I needed a quick throwaway Ubuntu VM for some testing, so I reached for the classic combo: an Ubuntu cloud image, a local cloud-init NoCloud datasource served over HTTP, and a bare qemu-system-x86_64 invocation. Nothing fancy, I've done this a dozen times before - just that the last time was ages ago.. My first attempt looked like this: root@vm:~# qemu-system-x86_64 -net nic \ -net user -machine…