Introduce nixos module for tclip

[fzakaria]

• Add a nixosModule
• Add an overlay

This how I tested it:

• Created separate flake.nix
• build it via nixos-rebuild build-vm --flake ".#test"

{
  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-24.05";
  inputs.tclip.url = "path:/home/fmzakari/code/github.com/tailscale-dev/tclip";
  outputs = {
    self,
    nixpkgs,
    tclip,
    ...
  }: let
    system = "x86_64-linux";
  in {
    # test is a hostname for our machine
    nixosConfigurations.test = nixpkgs.lib.nixosSystem {
      inherit system;
      modules = [
        tclip.nixosModules.default
        ({config, ...}: {
          users.users.alice = {
            isNormalUser = true;
            extraGroups = ["wheel"]; # Enable ‘sudo’ for the user.
            initialPassword = "test";
          };
          services.tclip.enable = true;
          # just give some fake file for now
          services.tclip.tailscaleAuthKeyFile = ./flake.lock;
          system.stateVersion = "24.05";
        })
      ];
    };
  };
}

Validation

<<< Welcome to NixOS 24.05.20240811.a731b45 (x86_64) - ttyS0 >>>

Run 'nixos-help' for the NixOS manual.

nixos login: alice
Password: 

[alice@nixos:~]$ which tclip
/run/current-system/sw/bin/tclip

[alice@nixos:~]$ tclip --help
Usage: tclip [filename]

Takes a file or standard in and posts it to your tailnet's tclip service. Returns a URL on standard out for sharing.

Flags:
  -n string
    	filename to use for pastes from standard input
  -target string
    	tclip server URL (default "http://paste")

[alice@nixos:~]$ systemctl status tclip
● tclip.service
     Loaded: loaded (/etc/systemd/system/tclip.service; enabled; preset: enable>
     Active: activating (auto-restart) (Result: exit-code) since Tue 2024-08-13>
    Process: 931 ExecStart=/nix/store/qfs9i87qa3m3yx84fq2amfjaijx5s3zb-unit-scr>
   Main PID: 931 (code=exited, status=2)
         IP: 0B in, 0B out
        CPU: 39ms

fixes #63

[fzakaria]

If I look at other examples https://github.com/ryantm/agenix they are structured differently; t
the overlay defines the packages and then packages attribute just pull it out of nixpkgs itself.

This goes in the other direction; not sure how "wrong" that is.

[fzakaria]

These changes are from formatting; I added formatter as an attribute so nix fmt should keep this consistent.

[fzakaria]

I would love if someone else can test this out too; I'll post on my twitter.

[fzakaria]

@Erisa let me know what you think.
I added more description to demonstrate it running in a VM.

The systemd service was failing to run because I gave it an invalid auth key.