NixOS cloud images available?

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1

Hi all!

I’ve been using NixOS on the desktop for a few months and want to use it more for servers as well. I wondered if there are original cloud images floating around? I’d like to add them to my Proxmox cluster as a template.

Currently, my workflow for deploying a Debian or Ubuntu machine is this:

  • Clone the Debian official cloud image;
  • Set cloudinit details;
  • Make disk larger;
  • Start the VM.

For NixOS, I currently don’t have a workflow like that.

Instead, I’ve done one or two VMs with nixos-generate and the minimal ISO, but it isn’t ideal. The thing is I’d like to offer the template to multiple users and things like username, ssh key and network configuration are fluid and can change with every deployment. Simply building an image with nixos-generate with hard-coded settings doesn’t cut it.

How are other people doing it? Am I missing something obvious?

2

You don’t have to hardcode the settings. We have a pve module that will let you create VMA files that can be directly restored as preconfigured VMs using qmrestore

Here’s a sample flake that shows the whole process of building and importing these cloud images:

{
        description = "A very basic flake";

        inputs.nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";

        outputs = { self, nixpkgs }: let
                pve_ssh_tgt = "root@192.168.1.150";
                vmid = "9918";
                vm_ip = "gw=192.168.1.1,ip=192.168.1.111/24";
        in {
                nixosConfigurations.test-vm = nixpkgs.lib.nixosSystem {
                        system = "x86_64-linux";
                        modules = [
                                ({lib, modulesPath, pkgs, ...}: {
                                        imports = [ "${modulesPath}/virtualisation/proxmox-image.nix" ];
                                        # These are only to populate the cloud-init default config
                                        # It can be changed on the PVE UI
                                        proxmox = {
                                                qemuConf = {
                                                        name = "test-vm";
                                                        cores = 2;
                                                        memory = 2048;
                                                };
                                                qemuExtraConf.ipconfig0 = vm_ip;
                                        };
                                        networking = {
                                                hostName = lib.mkForce "";
                                                useDHCP = false;
                                        };
                                        services = {
                                                cloud-init = {
                                                        enable = true;
                                                        network.enable = true;
                                                };
                                                getty.autologinUser = "root";
                                                sshd.enable = true;
                                        };
                                })
                        ];
                };
                packages.x86_64-linux.deploy = nixpkgs.legacyPackages.x86_64-linux.writeScriptBin "deploy" ''
                        VMA=$(tail -n1 ${
                                self.nixosConfigurations.test-vm.config.system.build.VMA
                        }/nix-support/hydra-build-products | awk '{print $NF}')
                        [ -z $VMA ] && false
                        scp $VMA ${pve_ssh_tgt}:/var/lib/vz/dump/vzdump-qemu-nixos-test.vma.zst
                        ssh ${pve_ssh_tgt} "qm stop ${vmid} && qm destroy ${vmid}; qmrestore local:backup/vzdump-qemu-nixos-test.vma.zst 9918 --unique --storage local-lvm && qm set ${vmid} --ide2 local-lvm:cloudinit && qm start ${vmid}"
                '';

        };
}

Update the parameters in the let block and run nix run .#deploy to test it out.

If you don’t want to have to build the VMA yourself, hydra builds them too. However, they don’t have cloud-init enabled, and are kinda useless out of the box. I’ll open a PR to enable cloud init by default.

EDIT: opened the PR

1 Like
3

Thank you for this!

I noticed you specified some VM specific settings in your config. Mainly a name and core count.

The goal is to create a Proxmox template that me and other users can clone, and get access to via the settings issued through cloud-init. This makes it very fast for everyone to spin up new NixOS VMs and is more akin to our current workflow for Debian and Ubuntu images.

4

Btw, this works vv well for me. it converts VMs into running NixOS. A really neat little tool.