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.
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
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.isoThe 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) | ✅ |
