test: vaultwarden microVM

example/microvm/boot-disk.nix

@@ -0,0 +1,69 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  inherit (config.system.boot.loader) kernelFile;
+  inherit (config.microvm) initrdPath;
+
+  kernelPath = "${config.microvm.kernel}/${kernelFile}";
+
+in
+{
+  options.microvm = with lib; {
+    bootDisk = mkOption {
+      type = types.path;
+      description = ''
+        Generated.
+
+        Required for Hypervisors that do not support direct
+        kernel+initrd loading.
+      '';
+    };
+  };
+
+  config = lib.mkIf config.microvm.guest.enable {
+    microvm.bootDisk =
+      pkgs.runCommandLocal "microvm-bootdisk.img"
+        {
+          nativeBuildInputs = with pkgs; [
+            parted
+            libguestfs
+          ];
+          LIBGUESTFS_PATH = pkgs.libguestfs-appliance;
+        }
+        ''
+          # kernel + initrd + slack, in sectors
+          EFI_SIZE=$(( ( ( $(stat -c %s ${kernelPath}) + $(stat -c %s ${initrdPath}) + 16 * 4096 ) / ( 2048 * 512 ) + 1 ) * 2048 ))
+
+          truncate -s $(( ( $EFI_SIZE + 2048 + 33 ) * 512 )) $out
+          echo Creating partition table
+          parted --script $out -- \
+            mklabel gpt \
+            mkpart ESP fat32 2048s $(( $EFI_SIZE + 2048 - 1 ))"s" \
+            set 1 boot on
+
+          echo Creating EFI partition
+          export HOME=`pwd`
+          guestfish --add $out run \: mkfs fat /dev/sda1
+          guestfs() {
+            guestfish --add $out --mount /dev/sda1:/ $@
+          }
+          guestfs mkdir /loader
+          echo 'default *.conf' > loader.conf
+          guestfs copy-in loader.conf /loader/
+          guestfs mkdir /loader/entries
+          cat > entry.conf <<EOF
+          title microvm.nix (${config.system.nixos.label})
+          linux /${kernelFile}
+          initrd /${baseNameOf initrdPath}
+          EOF
+          guestfs copy-in entry.conf /loader/entries/
+          guestfs copy-in ${kernelPath} /
+          guestfs copy-in ${initrdPath} /
+        '';
+  };
+}