Proxmox Virtual Environment
The instructions should work for PVE 7.2 and later with NixOS 22.05 and later. Users of previous versions may need to patch pve-container to use NixOS LXC images (instructions are below too).
KVM
It is possible to generate generic qcow2 images and attach them to VMs with qm importdisk as shown here.
A better option is to generate a VMA image that can be imported as a VM on proxmox. With this method, many VM configuration options such as CPU, memory, netowrk interfaces, and serial terminals can be specified in nix instead of manually setting them on the proxmox UI.
Generating VMA
The first run will take some time, as a patched version of qemu with support for the VMA format needs to be built
nix run github:nix-community/nixos-generators -- --format proxmox
Pass additional nix configuration to the template with --configuration filename.nix. In addition to NixOS module options, proxmox-specific options present in nixos/modules/virtualisation/proxmox-image.nix can be used to set core, memory, disk and other VM hardware options.
Deploying on proxmox
The generated vma.zst file can be copied to /var/lib/vz/dump/ (or any other configured VM dump storage path). A new VM can be spun up from it either using the GUI or the CLI:
qmrestore /var/lib/vz/dump/vzdump-qemu-nixos-21.11.git.d41882c7b98M.vma.zst <vmid> --unique true
note: the MAC address of net0 defaults to
00:00:00:00:00:00. This must either be overriden thruoghproxmox.qemuConf.net0, or theuniqueattribute must be set to true when importing the image on proxmox.
By default, the generated image is set up to expose a serial terminal interface for ease of access.
root@proxmox-server:~# qm start <vmid> root@proxmox-server:~# qm terminal <vmid> starting serial terminal on interface serial0 (press Ctrl+O to exit) <<< NixOS Stage 1 >>> loading module dm_mod... running udev... Starting version 249.4 . . . [ OK ] Reached target Multi-User System. <<< Welcome to NixOS 21.11.git.d41882c7b98M (x86_64) - ttyS0 >>> Run 'nixos-help' for the NixOS manual. nixos login: root (automatic login) [root@nixos:~]#
Network configuration
Cloud-init can be enabled with
services.cloud-init.network.enable = true;
This will enable systemd-networkd, allowing cloud-init to set up network interfaces on boot.
LXC
Generating LXC template
nix run github:nix-community/nixos-generators -- --format proxmox-lxc
Privileged LXCs
While it’s not necessary, proxmoxLXC.privileged can be set to true to enable the DebugFS mount in privileged LXCs. If enabled on unprivileged LXCs, this will fail to mount.
Network configuration
The proxmox LXC template uses systemd-networkd by default to allow network configuration by proxmox. proxmoxLXC.manageNetwork can be set to true to disable this.
deploying on proxmox
Copy the tarball to proxmox, then create a new LXC with this template through the web UI or the CLI. The “nesting” feature needs to be enabled. Newer versions of proxmox will have it enabled by default.
As of now, not all of the configuration options on the web UI work for proxmox LXCs. Network configuration and adding SSH keys to root user work, while setting a password for the root user and setting hostname don’t.
The template built above without any options does not come with /etc/nixos/configuration.nix. A minimal working example is presented below. Be sure to run nix-channel --update before nixos-rebuild switch.
{ pkgs, modulesPath, ... }:
{
imports = [
(modulesPath + "/virtualisation/proxmox-lxc.nix")
];
environment.systemPackages = [
pkgs.vim
];
}
Patching pve-container
This is not needed on pve-container version 4.1-5 (released on 27 April 2022) and newer. If you have an older version, you will have to patch it to add NixOS LXC support. If you have a newer version, skip ahead to the next section.
- install some dependencies
apt install git devscripts gdebi - clone https://github.com/proxmox/pve-container
root@pve:~# git clone https://github.com/proxmox/pve-container ... root@pve:~# cd pve-container/
- get the installed version of pve-container
root@pve:~/pve-container# pveversion -v | grep pve-container pve-container: 4.1-2
- check out the commit of the version you want
root@pve:~/pve-container# git log --grep "4.1-2"
commit 5d5f81f645bd1e8fd0ffff878fe249253e1be777
Author: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Fri Nov 12 19:21:25 2021 +0100
bump version to 4.1-2
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
root@pve:~/pve-container# git checkout 5d5f81f645bd1e8fd0ffff878fe249253e1be777 Note: switching to '5d5f81f645bd1e8fd0ffff878fe249253e1be777'. ... HEAD is now at 5d5f81f bump version to 4.1-2
- cherry-pick the patch that adds NixOS LXC support
root@pve:~/pve-container# git cherry-pick 6226d0101652914744cb5c657414bf286ccd857d Auto-merging src/PVE/LXC/Config.pm [detached HEAD 6f3cd03] Setup: add NixOS support Author: Harikrishnan R via pve-devel <pve-devel@lists.proxmox.com> Date: Tue Feb 15 22:58:46 2022 +0530 Committer: root <root@pve> ... 4 files changed, 50 insertions(+), 1 deletion(-) create mode 100644 src/PVE/LXC/Setup/NixOS.pm
If the version of pve-container you’re applying the patch to is older than 4.1, it might encounter merge conflicts that would need to be manually resolved.
- Install build deps
root@pve:~/pve-container# mk-build-deps ... The package has been created. Attention, the package has been created in the current directory, not in ".." as indicated by the message above!
root@pve:~/pve-container# gdebi pve-container-build-deps_4.1-2_all.deb Reading package lists... Done ... Fetched 432 MB in 6s (17.8 MB/s) ... Unpacking pve-container-build-deps (4.1-2) ... Setting up pve-container-build-deps (4.1-2) ...
- build the patched pve-container
root@pve:~/pve-container# make ... dpkg-buildpackage: info: binary-only upload (no source included) lintian pve-container_4.1-2_all.deb warning: running with root privileges is not recommended!
- install the deb
root@pve:~/pve-container# dpkg -i pve-container_4.1-2_all.deb
- verify that the installed pve-container package added NixOS support
root@pve:~# ls /usr/share/perl5/PVE/LXC/Setup/NixOS.pm /usr/share/perl5/PVE/LXC/Setup/NixOS.pm