Building custom NixOS images

[c0c0n3]

Look into building custom NixOS images to hit the ground running in a cloud deployment scenario. Not needed for now, but easily achievable with

• https://github.com/nix-community/nixos-generators

We can have a custom OS image for each kind of node we need to operate, e.g.

• Dev VM
• K8s master
• K8s slave
• etc.

Each image packs all the tools, services, etc. we need so after installation the node is ready to rock & roll.

[c0c0n3]

Going to sketch out how to build a custom image for the dev VM. Other images (e.g. AWS, GCE, etc.) can be built in the same way.

Create a devm-iso.nix file that bolts the teadal modules we want to enable on top of a bare-bones NixOS install.

{ config, pkgs, modulesPath, ... }:

{
  imports = [
    "${modulesPath}/installer/cd-dvd/installation-cd-minimal.nix"
  ];

  system.stateVersion = "22.11";

  teadal.devm.enable = true;
  teadal.swapfile.enable = true;
}

Then hook it up into our main flake.nix

{
  description = "Teadal cluster OS & tools.";

  inputs = {
    # ...
  };

  outputs = { self, nixos, nixpkgs, nixie }:
  let
     ...
  in
    { inherit overlay; } // pkgs // modules //
    {
      packages.x86_64-linux = {
        devm-iso = nixpkgs.nixos-generators.nixosGenerate {
          system = "x86_64-linux";
          modules = [
            ({ config, pkgs, ... }: { nixpkgs.overlays = [ overlay ]; })
            modules.nixosModules
            ./devm-iso.nix
          ];
          format = "install-iso";
        };
      };
    };
}

Build with

$ nix build .#devm-iso