mc-rtc-nix : the mc_rtc ecosystem in Nix

Warning

While being used daily by core maintainers of the framework, this is still considered a work-in-progress and usage / design choice may chage without notice.

This project contains:

• Package definitions for most of the mc_rtc ecosystem:
  • core framework mc_rtc and its dependencies
  • tools (mc-rtc-magnum for vizualisation, etc)
  • most robots supported by the framework, in particular those used at LIRMM and JRL
  • a limited set of downstream controllers and plugins
  • and more
• They are:
  • exposed in an overlay…
  • …with a reusable flake module built on top of flakoboros for easy integration in your projects with:
    • options to control how to build the framework in mc-rtc-nix.<option> (e.g with-ros=false, overlays.private=true, etc)
    • a superbuild module similar to mc-rtc-superbuild to configure the runtime dependencies of your project in mc-rtc-superbuild.<options>

Here is a quick primer on how to use its features:

Setup Nix

If you are here and don’t have nix yet, here is probably the easiest and fastest way to get started on ubuntu >= 24.04 “noble” / debian >= 13 “trixie” (because we need nix >= 2.18):

# 1. install the right apt package
sudo apt install -y nix-setup-systemd

# 2. activate the new CLI and flake features
echo 'experimental-features = nix-command flakes' | sudo tee -a /etc/nix/nix.conf

# 3. (optional) if you trust us, add our binary caches to avoid recompiling everything
echo 'extra-substituters = https://gepetto.cachix.org https://attic.iid.ciirc.cvut.cz/ros https://mc-rtc-nix.cachix.org' | sudo tee -a /etc/nix/nix.conf
echo 'extra-trusted-public-keys = gepetto.cachix.org-1:toswMl31VewC0jGkN6+gOelO2Yom0SOHzPwJMY2XiDY= ros:JR95vUYsShSqfA1VTYoFt1Nz6uXasm5QrcOsGry9f6Q= mc-rtc-nix.cachix.org-1:5M3sLvHXJCep4wc1tQl7QuFWL2eH2I0jkuvWtqJDYQs=' | sudo tee -a /etc/nix/nix.conf

# 4. activate your new nix.conf
sudo systemctl restart nix-daemon

# 5. allow yourself to use nix
sudo usermod -aG nix-users $(whoami)
newgrp nix-users

# 6. test everything is fine
nix run nixpkgs#ponysay it works

Other setup methods

If you don’t want this nix-setup-systemd apt package, other options include:

• Nix installer: https://nixos.org/download/
• Nix installer beta: https://github.com/NixOS/nix-installer
• Lix installer: https://lix.systems/install/

Use mc-rtc-nix directly

This [mc-rtc/nixpkgs] repository exposes packages, some of which may be used directly. To try out mc_rtc, you can use:

nix develop github:mc-rtc/nixpkgs#mc-rtc-superbuild-default

This will put you in a shell with mc_rtc and its default robots/controllers installed. To get started, use

(mc-rtc-magnum &) # run visualizer in the background
mc_rtc_ticker # run an open-loop controller

You should see the JVRC1 robot appear in the visualizer. If that is not the case and you are not on NixOS, you may need to configure Nix to use your graphics drivers. This can be achieved with

sudo nix run github:gepetto/nix#system-manager -- switch --flake github:gepetto/nix

Warning

This will install configurations system-wide (hence the sudo). If you are ensure about it, please read about system-manager