working build-vm tooling

configuration.nix

@@ -114,6 +114,7 @@
       # Required for containers under podman-compose to be able to talk to each other.
       defaultNetwork.settings.dns_enabled = true;
     };
+    diskSize = 262144;
   };
 
   services.tailscale.enable = true;

script/build-vm.sh

@@ -0,0 +1,59 @@
+#!/bin/sh
+
+set -eu
+
+build_dir="${build_dir:-/tmp/nixos-vm}"
+mount_point="${mount_point:-/tmp/fs}"
+qcow2="${qcow2:-${build_dir}/$(hostname -s).qcow2}"
+
+echo "[+] configuration:"
+echo "    build dir:    ${build_dir}"
+echo "  mount point:    ${mount_point}"
+echo "        image:    ${qcow2}"
+
+sleep 5
+
+echo "[+] updating NixOS config"
+cd /etc/nixos
+doas git pull --rebase local master
+
+if [[ -d "${build_dir}" ]]
+then
+    echo "[+] removing ${build_dir}"
+    sleep 2
+    rm -r "${build_dir}"
+fi
+
+mkdir "${build_dir}"
+cd "${build_dir}"
+nixos-rebuild build-vm
+
+echo "[+] Spinning up VM; kill it when you see the line"
+echo "	'Virtualisation disk image created.'"
+"${build_dir}/result/bin/run-$(hostname -s)-vm"
+doas qemu-img resize "${qcow2}" 256G
+
+doas modprobe nbd max_part=8
+
+echo "[+] connecting to network block driver"
+echo "    note: on failure, you may need to manually run"
+echo "    doas qemu-nbd --disconnect /dev/nbd0"
+doas qemu-nbd --connect=/dev/nbd0 ${qcow2}
+
+if [[ -d "${mount_point}" ]]
+then
+    echo "[+] removing ${mount_point}"
+    sleep 2
+    rm -r "${mount_point}"
+fi
+
+mkdir -p "${mount_point}"
+doas mount /dev/nbd0 "${mount_point}"
+
+rsync --progress -auvz "${HOME}/" "${mount_point}/home/kyle/"
+
+echo "[+] finished, cleaning up"
+doas unmount "${mount_point}"
+doas qemu-nbd --disconnect /dev/nbd0
+doas rmdir "${mount_point}"
+doas rm -r "${build_dir}"