The installation and usage of NixOSCompose differs in function of the state at which the project you are working on is. In the case of a new project you will want to install the nxc command line tool as it is described in Local Installation. If the project you are working on is already using NixOSCompose because you are developing it or in the case of the re-run of an experiment conducted in the past, you will prefer to use the version of nxc link to the project. Invoking nxc in an embedded way is described in Linked/project embedded nxc

Requirements

Quick note from NixOS wiki to activate flake feature

  • Non-NixOS

    Edit ~/.config/nix/nix.conf to add this line :

    experimental-features = nix-command flakes

  • NixOS

    Edit your configuration by adding the following options

    { pkgs, ... }: {
    nix = {
        package = pkgs.nixFlakes; # or versioned attributes like nixVersions.nix_2_8
        extraOptions = ''
            experimental-features = nix-command flakes
        '';
    };
}

`

Configuration requirements

On NixOS you need to enable Docker. To avoid compatibility issue with cgroupv2, it is also needed to force cgroupv1 with the option systemd.enableUnifiedCgroupHierarchy.

# Docker enabled + cgroup v1
virtualisation.docker.enable = true;
systemd.enableUnifiedCgroupHierarchy = false;

Local installation

The following commands will drop you in a shell where the nxc command is available and all required runtime dependencies (docker, vde2, tmux, qemu_kvm).

git clone https://gitlab.inria.fr/nixos-compose/nixos-compose.git
cd nixos-compose
nix develop .#nxcShell

Alternative

You can take advantage of the full potential of Nix's flakes. The following command will drop you in the same shell without having to clone the repository.

nix develop https://gitlab.inria.fr/nixos-compose/nixos-compose.git#nxcShell

Tip

Writting the full url is not really practical, an "alias" can be used.

nix registry add nxc git+https://gitlab.inria.fr/nixos-compose/nixos-compose.git

The command becomes :

nix develop nxc#nxcShell

`

Project embedded nxc

A project that is already using NixOSCompose in its experiments process provides an easy access to a shell that gives access to the nxc tool and its runtime dependencies if needed. This is achieved thanks to Nix and its flakes feature. By default, a project has a line in its flake.nix similar to this :

devShell.${system} = nxc.devShells.${system}.nxcShell;

It exposes the shell of NixOSCompose as in the previous section but with the specific revision thanks to the flake.lock file. The shell is accessible with the command nix develop. It is useful to explore what shells are available in the project, to list them you use nix flake show. Then to access the devShell of your choice use this command :

nix develop .#nxcShell

Info

Two shells availables :

  • nxcShellLite

    • python app nxc

  • nxcShell

    • python app nxc
    • docker
    • vde2
    • tmux
    • qemu_kvm