nixos/stage-1-systemd: Add mdraid support (+ test)

nixos/modules/module-list.nix

@@ -1186,6 +1186,7 @@
   ./system/boot/systemd/tmpfiles.nix
   ./system/boot/systemd/user.nix
   ./system/boot/systemd/initrd.nix
+  ./system/boot/systemd/initrd-mdraid.nix
   ./system/boot/timesyncd.nix
   ./system/boot/tmp.nix
   ./system/etc/etc-activation.nix

nixos/modules/system/boot/stage-1.nix

@@ -355,7 +355,7 @@ let
       [ { object = bootStage1;
           symlink = "/init";
         }
-        { object = pkgs.writeText "mdadm.conf" config.boot.initrd.mdadmConf;
+        { object = pkgs.writeText "mdadm.conf" config.boot.initrd.services.mdraid.mdadmConf;
           symlink = "/etc/mdadm.conf";
         }
         { object = pkgs.runCommand "initrd-kmod-blacklist-ubuntu" {
@@ -505,14 +505,6 @@ in
       '';
     };
 
-    boot.initrd.mdadmConf = mkOption {
-      default = "";
-      type = types.lines;
-      description = ''
-        Contents of <filename>/etc/mdadm.conf</filename> in stage 1.
-      '';
-    };
-
     boot.initrd.preLVMCommands = mkOption {
       default = "";
       type = types.lines;
@@ -736,6 +728,9 @@ in
     ];
 
     boot.initrd.supportedFilesystems = map (fs: fs.fsType) fileSystems;
-
   };
+
+  imports = [
+    (mkRenamedOptionModule [ "boot" "initrd" "mdadmConf" ] [ "boot" "initrd" "services" "mdraid" "mdadmConf" ])
+  ];
 }

nixos/modules/system/boot/systemd/initrd-mdraid.nix

@@ -0,0 +1,32 @@
+{ config, pkgs, lib, ... }: let
+
+  cfg = config.boot.initrd.services.mdraid;
+
+in {
+  options.boot.initrd.services.mdraid = {
+    enable = (lib.mkEnableOption "mdraid support in initrd") // {
+      visible = false;
+    };
+
+    mdadmConf = lib.mkOption {
+      description = "Contents of <filename>/etc/mdadm.conf</filename> in initrd.";
+      type = lib.types.lines;
+      default = "";
+    };
+  };
+
+  config = lib.mkIf (config.boot.initrd.systemd.enable && cfg.enable) {
+    boot.initrd.systemd = {
+      contents."/etc/mdadm.conf" = lib.mkIf (cfg.mdadmConf != "") {
+        text = cfg.mdadmConf;
+      };
+
+      initrdBin = [ pkgs.mdadm ];
+    };
+
+    boot.initrd.services.udev.packages = [ pkgs.mdadm ];
+    boot.initrd.systemd.packages = [ pkgs.mdadm ];
+
+    boot.kernelModules = [ "dm-raid" ];
+  };
+}

nixos/tests/all-tests.nix

@@ -518,6 +518,7 @@ in
   systemd-confinement = handleTest ./systemd-confinement.nix {};
   systemd-cryptenroll = handleTest ./systemd-cryptenroll.nix {};
   systemd-escaping = handleTest ./systemd-escaping.nix {};
+  systemd-initrd-mdraid = handleTest ./systemd-initrd-mdraid.nix {};
   systemd-initrd-simple = handleTest ./systemd-initrd-simple.nix {};
   systemd-journal = handleTest ./systemd-journal.nix {};
   systemd-machinectl = handleTest ./systemd-machinectl.nix {};

nixos/tests/systemd-initrd-mdraid.nix

@@ -0,0 +1,50 @@
+import ./make-test-python.nix ({ lib, pkgs, ... }: {
+  name = "systemd-initrd-mdraid";
+
+  nodes.machine = { pkgs, ... }: {
+    # Use systemd-boot
+    virtualisation = {
+      emptyDiskImages = [ 512 512 ];
+      useBootLoader = true;
+      useEFIBoot = true;
+    };
+    boot.loader.systemd-boot.enable = true;
+    boot.loader.efi.canTouchEfiVariables = true;
+
+    environment.systemPackages = with pkgs; [ mdadm e2fsprogs ]; # for mdadm and mkfs.ext4
+    boot.initrd = {
+      systemd = {
+        enable = true;
+        emergencyAccess = true;
+      };
+      services.mdraid = {
+        enable = true;
+        mdadmConf = ''
+          ARRAY /dev/md0 devices=/dev/vdc,/dev/vdd
+        '';
+      };
+      kernelModules = [ "raid0" ];
+    };
+
+    specialisation.boot-mdraid.configuration.virtualisation.bootDevice = "/dev/disk/by-label/testraid";
+  };
+
+  testScript = ''
+    # Create RAID
+    machine.succeed("mdadm --create --force /dev/md0 -n 2 --level=raid0 /dev/vdc /dev/vdd")
+    machine.succeed("mkfs.ext4 -L testraid /dev/md0")
+    machine.succeed("mkdir -p /mnt && mount /dev/md0 /mnt && echo hello > /mnt/test && umount /mnt")
+
+    # Boot from the RAID
+    machine.succeed("bootctl set-default nixos-generation-1-specialisation-boot-mdraid.conf")
+    machine.succeed("sync")
+    machine.crash()
+    machine.wait_for_unit("multi-user.target")
+
+    # Ensure we have successfully booted from the RAID
+    assert "(initrd)" in machine.succeed("systemd-analyze")  # booted with systemd in stage 1
+    assert "/dev/md0 on / type ext4" in machine.succeed("mount")
+    assert "hello" in machine.succeed("cat /test")
+    assert "md0" in machine.succeed("cat /proc/mdstat")
+  '';
+})