nixos/modules/virtualization/default.nix

inputs:
{
	options.nixos.virtualization = let inherit (inputs.lib) mkOption types; in
	{
		waydroid.enable = mkOption { default = false; type = types.bool; };
		docker.enable = mkOption { default = false; type = types.bool; };
		kvmHost =
		{
			enable = mkOption { default = false; type = types.bool; };
			gui = mkOption { default = false; type = types.bool; };
			autoSuspend = mkOption { type = types.listOf types.string; };
		};
	};
	config = let inherit (inputs.lib) mkMerge mkIf; in mkMerge
	[
		# waydroid
		(mkIf inputs.config.nixos.virtualization.waydroid.enable { virtualisation = { waydroid.enable = true; }; })
		# docker
		(
			mkIf inputs.config.nixos.virtualization.docker.enable { virtualisation.docker =
			{
				enable = true;
				rootless = { enable = true; setSocketVariable = true; };
				enableNvidia = true;
				storageDriver = "overlay2";
			};}
		)
		# kvmHost
		(
			mkIf inputs.config.nixos.virtualization.kvmHost.enable
			{
				boot =
				{
					kernelModules = 
						let
							modules =
							{
								intel = [ "kvm-intel" ];
								amd = [];
							};
						in
							builtins.concatLists (builtins.map (cpu: modules.${cpu}) inputs.config.nixos.hardware.cpu);
					extraModprobeConfig =
						let
							configs =
							{
								intel = "options kvm_intel nested=1";
								amd = "";
							};
						in
							builtins.concatStringsSep "\n" (builtins.map (cpu: configs.${cpu}) inputs.config.nixos.hardware.cpu);
				};
				virtualisation =
				{
					libvirtd = { enable = true; qemu.runAsRoot = false; onBoot = "ignore"; onShutdown = "shutdown"; };
					spiceUSBRedirection.enable = true;
				};
				environment.systemPackages = with inputs.pkgs; [ qemu_full win-spice ] ++
					(if (inputs.config.nixos.virtualization.kvmHost.gui) then [ virt-manager ] else []);
				systemd.services =
					let
						virsh = "${inputs.pkgs.libvirt}/bin/virsh";
						hibernate = inputs.pkgs.writeShellScript "libvirt-hibernate" (inputs.localLib.stripeTabs
						''
							if [ "$(LANG=C ${virsh} domstate $1)" = 'running' ]
							then
								if ${virsh} dompmsuspend "$1" disk
								then
									echo "Waiting for $1 to suspend"
									while ! [ "$(LANG=C ${virsh} domstate $1)" = 'shut off' ]
									do
										sleep 1
									done
									echo "$1 suspended"
									touch "/tmp/libvirt.$1.suspended"
								else
									echo "Failed to suspend $1"
								fi
							fi
						'');
						resume = inputs.pkgs.writeShellScript "libvirt-resume" (inputs.localLib.stripeTabs
						''
							if [ "$(LANG=C ${virsh} domstate $1)" = 'shut off' ] && [ -f "/tmp/libvirt.$1.suspended" ]
							then
								if ${virsh} start "$1"
								then
									echo "Waiting for $1 to resume"
									while ! [ "$(LANG=C ${virsh} domstate $1)" = 'running' ]
									do
										sleep 1
									done
									echo "$1 resumed"
									rm "/tmp/libvirt.$1.suspended"
								else
									echo "Failed to resume $1"
								fi
							fi
						'');
						makeHibernate = machine:
						{
							name = "libvirt-hibernate-${machine}";
							value =
							{
								description = "libvirt hibernate ${machine}";
								wantedBy = [ "systemd-hibernate.service" "systemd-suspend.service" ];
								before = [ "systemd-hibernate.service" "systemd-suspend.service" ];
								serviceConfig = { Type = "oneshot"; ExecStart = "${hibernate} ${machine}"; };
							};
						};
						makeResume = machine:
						{
							name = "libvirt-resume-${machine}";
							value =
							{
								description = "libvirt resume ${machine}";
								wantedBy = [ "systemd-hibernate.service" "systemd-suspend.service" ];
								after = [ "systemd-hibernate.service" "systemd-suspend.service" ];
								serviceConfig = { Type = "oneshot"; ExecStart = "${resume} ${machine}"; };
							};
						};
						makeServices = serviceFunction: builtins.map serviceFunction
							inputs.config.nixos.virtualization.kvmHost.autoSuspend;
					in
						builtins.listToAttrs (makeServices makeHibernate ++ makeServices makeResume);
			}
		)
	];
}

# sudo waydroid shell wm set-fix-to-user-rotation enabled