Add virtualisation.vmVariantWithDisko option

docs/interactive-vm.md

@@ -12,6 +12,16 @@ afterwards you can run the interactive VM with:
 result/bin/disko-vm
 ```
 
+You can configure the VM using the `virtualisation.vmVariantWithDisko` NixOS option:
+
+```nix
+{
+  virtualisation.vmVariantWithDisko = {
+    virtualisation.fileSystems."/persist".neededForBoot = true;
+  };
+}
+```
+
 extraConfig that is set in disko.tests.extraConfig is also applied to the interactive VMs.
 imageSize of the VMs will be determined by the imageSize in the disk type in your disko config.
 memorySize is set by disko.memSize

lib/default.nix

@@ -16,7 +16,7 @@ let
     # a version of makeDiskImage which runs outside of the store
     makeDiskImagesScript = args: (import ./make-disk-image.nix ({ inherit diskoLib; } // args)).impure;
 
-    makeVMRunner = args: (import ./interactive-vm.nix ({ inherit diskoLib; } // args)).pure;
+    makeVMRunner = args: import ./interactive-vm.nix ({ inherit diskoLib; } // args);
 
     testLib = import ./tests.nix { inherit lib makeTest eval-config; };
     # like lib.types.oneOf but instead of a list takes an attrset

lib/interactive-vm.nix

@@ -1,8 +1,6 @@
 { nixosConfig
 , diskoLib
 , pkgs ? nixosConfig.pkgs
-, name ? "${nixosConfig.config.networking.hostName}-disko-images"
-, extraConfig ? { }
 }:
 let
   lib = pkgs.lib;
@@ -47,34 +45,22 @@ let
       driveExtraOpts.werror = "report";
     })
     (builtins.tail disks);
-  vm = (nixosConfig.extendModules {
+in nixosConfig.extendModules {
   modules = [
-      ({ modulesPath, ... }: {
+    ({ modulesPath, config, pkgs, ... }: {
       imports = [
         (modulesPath + "/virtualisation/qemu-vm.nix")
       ];
-      })
-      {
-        virtualisation.useEFIBoot = nixosConfig.config.disko.tests.efi;
-        virtualisation.memorySize = nixosConfig.config.disko.memSize;
+
+      virtualisation.useEFIBoot = config.disko.tests.efi;
+      virtualisation.memorySize = config.disko.memSize;
       virtualisation.useDefaultFilesystems = false;
       virtualisation.diskImage = null;
       virtualisation.qemu.drives = [ rootDisk ] ++ otherDisks;
       boot.zfs.devNodes = "/dev/disk/by-uuid"; # needed because /dev/disk/by-id is empty in qemu-vms
       boot.zfs.forceImportAll = true;
-      }
-      {
-        # generated from disko config
-        virtualisation.fileSystems = cfg_.disko.devices._config.fileSystems;
-        boot = cfg_.disko.devices._config.boot or { };
-        swapDevices = cfg_.disko.devices._config.swapDevices or [ ];
-      }
-      nixosConfig.config.disko.tests.extraConfig
-    ];
-  }).config.system.build.vm;
-in
-{
-  pure = pkgs.writers.writeDashBin "disko-vm" ''
+
+      system.build.vmWithDisko = pkgs.writers.writeDashBin "disko-vm" ''
         set -efux
         export tmp=$(mktemp -d)
         trap 'rm -rf "$tmp"' EXIT
@@ -84,6 +70,15 @@ in
           -F qcow2 "$tmp"/${disk.name}.qcow2
         '') disks}
         set +f
-    ${vm}/bin/run-*-vm
+        ${config.system.build.vm}/bin/run-*-vm
       '';
+    })
+    {
+      # generated from disko config
+      virtualisation.fileSystems = cfg_.disko.devices._config.fileSystems;
+      boot = cfg_.disko.devices._config.boot or { };
+      swapDevices = cfg_.disko.devices._config.swapDevices or [ ];
+    }
+    nixosConfig.config.disko.tests.extraConfig
+  ];
 }

module.nix

@@ -7,6 +7,11 @@ let
     eval-config = import (pkgs.path + "/nixos/lib/eval-config.nix");
   };
   cfg = config.disko;
+
+  vmVariantWithDisko = diskoLib.makeVMRunner {
+    inherit pkgs;
+    nixosConfig = args;
+  };
 in
 {
   options.disko = {
@@ -137,6 +142,16 @@ in
       };
     };
   };
+
+  options.virtualisation.vmVariantWithDisko = lib.mkOption {
+    description = ''
+      Machine configuration to be added for the vm script available at `.system.build.vmWithDisko`.
+    '';
+    inherit (vmVariantWithDisko) type;
+    default = {};
+    visible = "shallow";
+  };
+
   config = lib.mkIf (cfg.devices.disk != { }) {
     system.build = (cfg.devices._scripts { inherit pkgs; checked = cfg.checkScripts; }) // {
 
@@ -161,10 +176,7 @@ in
         extraTestScript = cfg.tests.extraChecks;
       };
 
-      vmWithDisko = diskoLib.makeVMRunner {
-        inherit pkgs;
-        nixosConfig = args;
-      };
+      vmWithDisko = lib.mkDefault config.virtualisation.vmVariantWithDisko.system.build.vmWithDisko;
     };