Nixpkgs is an ever-increasing assortment of software program packages for Nix and NixOS. Even with greater than 80,000 packages, you simply run in a scenario the place there’s a performance that’s not but applied.
Earlier this yr, we wrote a tutorial on tips on how to implement your individual package deal in NixOS. The implementation of the package deal within the system was tedious and required holding observe of the package deal you needed to implement.
Let’s dive right into a sensible instance: LXD is a container and digital machine supervisor. It endorses digital machines natively since LXD 4.0. Nevertheless, operating on NixOS breaks the characteristic, and we have now to seek out workarounds to make use of it. To permit LXD to begin digital machines on NixOS, we want a repair, and we wish it to be each reproducible and moveable.
To take action, we’re utilizing the lxd-agent characteristic which successfully repair the aforementionned subject. It was launched by astridyu, a contributor to nixpkgs. It has not but been applied within the Grasp department of nixpkgs and is, as of 19/04/2022, a pull request.
Our aim is to combine the pull request to our nixpkgs to have the ability to begin digital machines. For this, we’ll use Flakes. It’s an experimental characteristic of the Nix package deal supervisor that enables reproducibility within the deployment of dependencies. We use it to assemble totally different nixpkgs collectively. It’s a trait often called composability.
If the pull request has been merged, this tutorial turns into irrelevant. To get the performance, replace your Nix or NixOS to the present model of the grasp department.
Stipulations
Step 1 – Putting in ZFS
ZFS is a filesystem that we use to generate storage swimming pools in LXD. It’s the solely filesystem supported by this methodology, for now.
ZFS should be put in on the NixOS machine previous to the set up of LXD. To take action, go to your configuration.nix file situated in /and so forth/nixos/ and add the next strains to your configuration.
boot = {
initrd.supportedFilesystems = [ "zfs" ];
supportedFilesystems = [ "zfs" ];
zfs.requestEncryptionCredentials = true;
loader.grub.copyKernels=true;
kernelParams= [ "nohibernate" ];
};
providers.zfs = {
autoScrub.allow = true;
autoSnapshot.allow = true;
};Within the file, the networking.hostId property should be set. It’s a bit tough as a result of it solely accepts 32bit ID that you simply generate on the terminal with head -c 8 /and so forth/machine-id.
With this ID, go to your configuration file and set it.
networking = {
hostId = "" ;
};Now, rebuild the swap drive. That is achieved by doing sudo nixos-rebuild swap.
If the construct fails as a result of you have already got LXD put in, seek advice from this section of the article.
Step 2 – Putting in Flakes
To put in Flakes, merely put, in configuration.nix:
nix = {
package deal = pkgs.nixFlakes;
extraOptions = ''experimental-features = nix-command flakes'';
};It’s essential to rebuild your swap drive once more.
Getting began with Flakes
We are going to draw on the facility of Flakes to patch our system by combining totally different variations of nixpkgs. The variations we’ll use are:
You possibly can observe the pull request with its quantity: #166858.
Then, we’ll proceed to override the LXD package deal from the nixpkgs grasp department model with astridyu’s nixpkgs lxd-vms department model to get the lxd-agent characteristic utilized onto LXD.
To make use of Flakes, it’s required to create a flake.nix file in /and so forth/nixos. That is carried out by doing sudo nano /and so forth/nixos/flake.nix.
On this file, we describe which nixpkgs repository we wish to add to our configuration, and tips on how to merge them.
Be aware: Confirm that your hostname, is outlined below the
networking.hostNamediscipline in your configuration. It’s required.
{
description = "NixOS Configuration of LXD";
inputs = {
nixpkgs.url = "nixpkgs/grasp";
nixpkgs-lxdvm = {
url = "github:astridyu/nixpkgs/lxd-vms";
};
};
outputs = { self, nixpkgs, nixpkgs-lxdvm }:
let
system = "x86_64-linux";
overlay-lxdvm = remaining: prev: {
lxdvm = import nixpkgs-lxdvm {
inherit system;
config.allowUnfree = true;
};
};
in {
nixosConfigurations."" = nixpkgs.lib.nixosSystem {
inherit system;
modules = [
({ config, pkgs, ... }: { nixpkgs.overlays = [ overlay-lxdvm ]; })
./configuration.nix
];
};
};
}Putting in LXD
We should modify our configuration.nix to allow LXD virtualization.
boot.kernelModules = ["vhost_vsock"];
virtualisation = {
lxd = {
allow=true;
package deal = pkgs.lxdvm.lxd.override {useQemu = true;};
recommendedSysctlSettings=true;
};
};We rebuild the swap drive. It’s required to make use of the --impure choice upon rebuilding whether it is requested by the system.
The rationale behind that is that Flakes runs in pure analysis mode which is underdocumented. Flakes forbids the utilization of absolute paths, which might trigger the analysis to be impure. This may increasingly occur as a result of we’re operating unsupported packages.
Getting began with LXD and Digital Machines
To get began with LXD, we advocate that you simply initialize a storage pool. That is carried out by sudo lxd init.
Afterwards, questions are requested regarding the first storage pool that LXD creates. We advocate this configuration for the primary utilization.
Would you want to make use of LXD clustering? (sure/no) [default=no]: no
Do you wish to configure a brand new storage pool? (sure/no) [default=yes]: sure
Title of the brand new storage pool [default=default]: test-storage
Title of the storage backend to make use of (btrfs, dir, zfs) [default=zfs]: zfs
Create a brand new ZFS pool? (sure/no) [default=yes]:
Would you want to make use of an current empty block machine (e.g. a disk or partition)? (sure/no) [default=no]:
Dimension in GB of the brand new loop machine (1GB minimal) [default=30GB]:
Would you want to hook up with a MAAS server? (sure/no) [default=no]:
Would you prefer to create a brand new native community bridge? (sure/no) [default=yes]:
What ought to the brand new bridge be known as? [default=lxdbr0]: test-bridge
What IPv4 handle ought to be used? (CIDR subnet notation, “auto” or “none”) [default=auto]:
What IPv6 handle ought to be used? (CIDR subnet notation, “auto” or “none”) [default=auto]:
Would you just like the LXD server to be obtainable over the community? (sure/no) [default=no]:
Would you want stale cached pictures to be up to date routinely? (sure/no) [default=yes]:
Would you want a YAML "lxd init" preseed to be printed? (sure/no) [default=no]:When there is no such thing as a response, default is assumed.
As soon as the storage pool is configured, new digital machines may be initialized with lxc launch . It routinely downloads the picture of your digital machine and units one up.
To examine your digital machines, do lxc ls.
Widespread points
If the rebuild fails, it is because of LXD already being put in. This results in nixos-rebuild swap not succeeding as a result of an LXD storage pool already exists. It signifies that volumes are nonetheless mounted, and it’s essential to delete them as a result of it’s essential to rebuild LXD from scratch.
Begin by regenerating your hardware-configuration.nix by doing nixos-generate-config.
On this file, the trail to your mounted volumes is talked about, and it’s essential to dismount and take away them within the following method:
sudo umount -v /var/lib/lxd/storage-pools/to dismount the storage pool.sudo rm -r /var/lib/lxdto delete the entire LXD folder.
Rebuilding your system is critical once more.
Conclusion
Congratulations! You are actually capable of launch digital machines utilizing LXD on NixOS, and also you realized tips on how to use flakes to create an overlay on your nixpkgs.
This methodology will turn into out of date as soon as the pull request is merged, but it surely stays related if you wish to combine options that aren’t within the grasp department.
