How does the installation process work?

[Guelakais]

To be honest, either I don't understand it or it's not clearly described. I've read the readme and looked at the examples and unfortunately it's not clear to me. Do you know what I need to put in my config to make the ros2 installation process via sudo nixos-rebuild switch work?

{ config, pkgs, builtins,stdenv, ... }:
let
  nixvim = import (builtins.fetchGit {url = "https://github.com/nix-community/nixvim";});
in
let 
  rosDocker=import (builtins.fetchGit{url="https://gitlab.com/docker5348/ros2_main_dev_container";});
in
{
  imports = [
    /etc/nixos/hardware-configuration.nix
  ];
  nix={
    gc = {
      automatic = true;
      dates = "daily";
    };
    settings.auto-optimise-store=true;
  };

  # paste your boot config here...
  boot.loader = {
    systemd-boot.enable = true;
    efi.canTouchEfiVariables = true;
    };

  virtualisation.docker.enable = true;
  networking = {
    firewall = {
      enable = true;
      allowedTCPPorts = [];
      allowedUDPPorts = [];
    };
    hostName = "Azrael";
    networkmanager.enable = true;
  };

  # edit as per your location and timezone
  time.timeZone = "Europe/Berlin";

  i18n = {
    defaultLocale = "en_GB.UTF-8";
    extraLocaleSettings = {
      LC_ADDRESS = "de_DE.UTF-8";
      LC_IDENTIFICATION = "de_DE.UTF-8";
      LC_MEASUREMENT = "de_DE.UTF-8";
      LC_MONETARY = "de_DE.UTF-8";
      LC_NAME = "de_DE.UTF-8";
      LC_NUMERIC = "de_DE.UTF-8";
      LC_PAPER = "de_DE.UTF-8";
      LC_TELEPHONE = "de_DE.UTF-8";
      LC_TIME = "de_DE.UTF-8";
      LC_CTYPE="en_US.utf8"; # required by dmenu don't change this
    };
  };

  sound.enable = true;

    services = {

      printing.enable = true;

      xserver = {
        xkb={
          layout = "eu";
          variant = "";
          };
      libinput.enable = true;
        enable = true;
        windowManager.i3 = {
          enable = true;
          };
      desktopManager = {
            xterm.enable = true;
            xfce = {
              enable = true;
              noDesktop = true;
              enableXfwm = false;
            };
        };
        displayManager = {
            lightdm.enable = true;
            defaultSession = "xfce+i3";
        };
      }; # xserver
        gvfs.enable = true;
        gnome.gnome-keyring.enable = true;
        blueman.enable = true;
        pipewire = {
          enable = true;
          alsa = {
              enable = true;
              support32Bit = true;
          };
          pulse.enable = true;
        };
      };
      nixpkgs = {
        config = {
          allowUnfree = true;
          pulseaudio = true;
        };
      };

      users.users.azrael = {
        isNormalUser = true;
        description = "azrael";
        extraGroups = [ "networkmanager" "wheel" "docker" ];
      }; # services

    environment = {
      variables= {
        SRC_ENDPOINT = "https://sourcegraph.example.com";
        SRC_SRC_ACCESS_TOKEN="'cat ${config.users.users.azrael.home}/sourcegraphToken'";
      };
      systemPackages = with pkgs; [
        alacritty
      catimg
      curl
        cargo
        clang
        dmenu
        docker
        firefox
        fuse
        gcc
      git
      gimp
        gnome.gnome-keyring
        gr-framework
        i3
        i3status
        inkscape
        jabref
        julia
        just
        kate
        lazygit
        libclang
        nerdfonts
      networkmanagerapplet
        neovim
        nitrogen
        pasystray
        obsidian
        openjdk
        openscad-unstable
        picom
        pkg-config
        polkit_gnome
        pulseaudioFull
        python311
        python311Packages.polars
        python311Packages.numpy
      python311Packages.scipy
      python311Packages.pip
      rofi
        roboto
        rustc
        rustup
        steam
        tectonic
        thunderbird
        unrar
        unzip
        ucs-fonts
        vcstool
        vim
        vscode
        wget
        xclip
        xorg.xhost
        xorg.libX11
        x11docker
        zip
        (vscode-with-extensions.override {
        vscodeExtensions = with vscode-extensions; [
          bbenoist.nix
          ms-azuretools.vscode-docker
          ms-python.python
          ms-toolsai.jupyter
          ms-toolsai.jupyter-keymap
          ms-toolsai.jupyter-renderers
          ms-toolsai.vscode-jupyter-slideshow
          ms-toolsai.vscode-jupyter-cell-tags
          ms-vscode-remote.remote-ssh
          serayuzgur.crates
          tamasfe.even-better-toml
          ] ++ pkgs.vscode-utils.extensionsFromVscodeMarketplace [{
            name = "remote-ssh-edit";
            publisher = "ms-vscode-remote";
            version = "0.47.2";
            sha256 = "1hp6gjh4xp2m1xlm1jsdzxw9d8frkiidhph6nvl24d0h8z34w49g";
          }];
      })
      ];
  }; # environment

    programs = {
      bash.shellAliases = {
        sudo="sudo ";
        sshEval="eval $(ssh-agent -s)";
        nixos_list_generations="sudo nix-env --list-generations --profile /nix/var/nix/profiles/system";
        nixosRebuild="sudo nixos-rebuild switch";
        dockerRmContainters="docker ps -a | awk '{print $NF}' | while read -r container_name; do docker rm $container_name; done";
        dockerRmImages="docker image ls --quiet --no-trunc | while read -r image_id; do docker image rm $image_id; done";
      };
      dconf.enable = true;
      firefox={
        enable=true;

      };
      git.enable = true;
      neovim = {
        enable = true;
        defaultEditor = true;
      };
      steam = {
        enable = true;
        remotePlay.openFirewall = true;
        dedicatedServer.openFirewall = true;
      };
    thunar.enable = true;
    };

    security = {
    polkit.enable = true;
      rtkit.enable = true;
  };

  systemd={
    tmpfiles.settings = {
      "ros2_docker_folders" = {
        "${config.users.users.azrael.home}/ros2_ws/src" = {d.mode = "0777";};
        "${config.users.users.azrael.home}/microros_ws/src" = {d.mode = "0777";};
        "${config.users.users.azrael.home}/ros2_debug/src"= {d.mode = "0777";};
      };
      "projects_folders"={
        "${config.users.users.azrael.home}/projects"= {d.mode = "0777";};
        "${config.users.users.azrael.home}/projects/rust"= {d.mode = "0777";};
        "${config.users.users.azrael.home}/projects/julia"= {d.mode = "0777";};
        "${config.users.users.azrael.home}/projects/python"= {d.mode = "0777";};
        "${config.users.users.azrael.home}/projects/latex"= {d.mode = "0777";};
        "${config.users.users.azrael.home}/projects/java"= {d.mode = "0777";};
      };
    };
    user.services.polkit-gnome-authentication-agent-1 = {
      description = "polkit-gnome-authentication-agent-1";
      wantedBy = [ "graphical-session.target" ];
      wants = [ "graphical-session.target" ];
      after = [ "graphical-session.target" ];
      serviceConfig = {
        Type = "simple";
        ExecStart =
          "${pkgs.polkit_gnome}/libexec/polkit-gnome-authentication-agent-1";
        Restart = "on-failure";
        RestartSec = 1;
        TimeoutStopSec = 10;
      };
    };
  };

  hardware.bluetooth.enable = true;

  # Don't touch this
  system={
    activationScripts={
    script.text =
    ''
       echo "Udo!"
    '';
    };
    stateVersion = "unstable";
    };
}

[lopsided98]

If you are just doing development or running ROS processes manually, you don't put anything in your NixOS config. The NixOS modules are only needed if you want to start ROS processes at boot (i.e. you are running NixOS on your robot).

Otherwise, you just use a shell file like one of the examples and enter the shell using nix-shell or nix develop if using flakes.

[Guelakais]

To be honest, it's too complicated for me. I haven't dealt with flakes yet and run my ros2 applications using a Docker container that I have developed. I will look into it when the standard ros2 packages, like gazebo, rviz or the ros2 command line tool, can be included in the config as normal.