deprecated: nixos-generators

Starting with NixOS 25.05, most of nixos-generators has been upstreamed into nixpkgs.

So we believe it's time to retire nixos-generators, a good 8 years after its initial commit and after countless built images. Please let us know if you run into any trouble, such as missing features, during the migration.

The main, user-visible difference is the new nixos-rebuild build-image command, which replaces the venerable nixos-generate. Check its manual section or below to see how it works.

Usage of nixos-rebuild build-images

To build an ISO image, using the new nixos-rebuild build-image, run:

nixos-rebuild build-image --image-variant iso

Or to explicitly specifiy the path to your NixOS configuration as well as the nixpkgs checkout to use:

NIX_PATH=nixpkgs=../nixpkgs NIXOS_CONFIG="/etc/nixos/nixos-configuration.nix" nixos-rebuild build-image --image-variant iso

...with Flakes

To build a simple ISO image, from a nixosConfigurations.myhost output of your flake, run:

nixos-rebuild build-image --image-variant iso --flake .#myhost

Or, if you prefer to expose an installable similar to the old nixos-generators.nixosGenerate nix function, you could use the right attribute of system.build.images:

packages.x86_64-linux.myhost-iso = self.nixosConfigurations.myhost.config.system.build.images.iso

Formats of nixos-generators

The third column describes whether they are supported image variants in nixos-rebuild build-image:

format	description	supported in nixpkgs
amazon	Amazon EC2 image	✅
azure	Microsoft azure image (Generation 1 / VHD)	✅
cloudstack	qcow2 image for cloudstack.	✅
do	Digital Ocean image	✅
docker	Docker image (uses systemd to run, probably only works in podman)
gce	Google Compute image	✅
hyperv	Hyper-V Image (Generation 2 / VHDX)	✅
install-iso	Installer ISO	✅ (called iso-installer)
install-iso-hyperv	Installer ISO with enabled hyper-v support	use the hyperv variant and customize it.
iso	ISO	✅
kexec	kexec tarball (extract to / and run /kexec_nixos)	✅
kexec-bundle	same as before, but it's just an executable	Use the kexec variant above.
kubevirt	KubeVirt image	✅
linode	Linode image	✅
lxc	create a tarball which is importable as an lxc container, use together with lxc-metadata	✅
lxc-metadata	the necessary metadata for the lxc image to start, usage: lxc image import $(nixos-generate -f lxc-metadata) $(nixos-generate -f lxc)	✅
openstack	qcow2 image for openstack	✅
proxmox	VMA file for proxmox	✅
proxmox-lxc	LXC template for proxmox	✅
qcow	qcow2 image	✅
qcow-efi	qcow2 image with efi support	✅
raw	raw image with bios/mbr. for physical hardware, see the 'raw and raw-efi' section	✅
raw-efi	raw image with efi support. for physical hardware, see the 'raw and raw-efi' section	✅
sd-aarch64	Like sd-aarch64-installer, but does not use default installer image config.	use sd-card and set system to aarch64-linux
sd-aarch64-installer	create an installer sd card for aarch64. For cross compiling use --system aarch64-linux and read the cross-compile section.	use sd-card and set system to aarch64-linux
sd-x86_64	sd card image for x86_64 systems	use sd-card and set system to x86_64-linux
vagrant-virtualbox	VirtualBox image for Vagrant	✅
virtualbox	virtualbox VM	✅
vm	only used as a qemu-kvm runner	use nixos-rebuild build-vm
vm-bootloader	same as vm, but uses a real bootloader instead of netbooting	use nixos-rebuild build-vm-with-bootloader
vm-nogui	same as vm, but without a GUI	use nixos-rebuild build-vm and customize it.
vmware	VMWare image (VMDK)	✅