test-nixos-iso.sh

#!/usr/bin/env nix-shell
#!nix-shell -i bash -p bash -p qemu_kvm -p iproute2

set -x -eu -o pipefail

VM_IMAGE=""
CPUS="${CPUS:-$(nproc)}"
MEMORY="${MEMORY:-4096}"
SSH_PORT="${SSH_PORT:-2222}"
IMAGE_SIZE="${IMAGE_SIZE:-10G}"

extra_flags=()
if [[ -n "${OVMF:-}" ]]; then
  extra_flags+=("-bios" "$OVMF")
fi

# https://hydra.nixos.org/job/nixos/unstable-small/nixos.iso_minimal.x86_64-linux
iso=/nix/store/xgkfnwhi3c2lcpsvlpcw3dygwgifinbq-nixos-minimal-23.05pre483386.f212785e1ed-x86_64-linux.iso
nix-store -r "$iso"

for arg in "${@}"; do
  case "$arg" in
      prepare)
          truncate -s"$IMAGE_SIZE" nixos-nvme1.img nixos-nvme2.img
          ;;
      start)
          qemu-system-x86_64 -m "${MEMORY}" \
              -boot n \
              -smp "${CPUS}" \
              -enable-kvm \
              -cpu max \
              -netdev "user,id=mynet0,hostfwd=tcp::${SSH_PORT}-:22" \
              -device virtio-net-pci,netdev=mynet0 \
              -drive file=nixos-nvme2.img,if=none,id=nvme1,format=raw \
              -device nvme,serial=deadbeef1,drive=nvme1 \
              -drive file=nixos-nvme1.img,if=none,id=nvme2,format=raw \
              -device nvme,serial=deadbeef2,drive=nvme2 \
              -cdrom "$iso"/iso/*.iso \
              "${extra_flags[@]}"
          # after start, go to the console and run:
          # passwd
          # than you can ssh into the machine:
          # ssh -p 2222 nixos@localhost
          ;;
      destroy)
          rm -f "$VM_IMAGE"
          ;;
      *)
          echo "USAGE: $0 (prepare|start|destroy)"
          ;;
  esac
done