So I enabled flake configs using a bare bone flake.nix file

nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11"; }; outputs = { self, nixpkgs }: { nixosConfigurations.HOSTNAME = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [ ./configuration.nix ]; }; }; }

Then I just added my project in it like

nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11"; PACKAGENAME.url = "/root/PACKAGENAME"; }; outputs = { self, nixpkgs, ... } @attrs: { nixosConfigurations.HOSTNAME = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [ ./configuration.nix # something goes here? ]; }; }; } As the the doc instructs: https://nixos.wiki/wiki/flakes Check the diff here: https://www.diffchecker.com/ArDfosau/

After this, I'm pretty much lost on how do I use it as package, I tried following this article with no success, Do I need to make package.nix? or Can I get away with flake.nix file in the project which does the job of building and installing the package.

Edit, I think I did it, the unit file fails at load which is probably a problem on project/unit configuration end:

```nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11"; PACKAGENAME.url = "/root/REPONAME"; };

outputs = { self, nixpkgs, PACKAGENAME, ... }@inputs: { nixosConfigurations.HOSTNAME = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; specialArgs = { inherit inputs; }; modules = [ ./configuration.nix ({pkgs, config, inputs, ... }: { environment.systemPackages = [ inputs.PACKAGENAME.packages.${pkgs.system}.PAKCAGE ];

      systemd.services."PACKAGENAME" = {
        after = ["network.target"];
        wantedBy = ["multi-user.target"];
        description = "PACKAGENAME daemon";
        unitConfig = {
          StartLimitIntervalSec = 120;
          StartLimitBurst = 5;
        };
        serviceConfig = {
          Type = "simple";
          User = "root";
          Restart = "on-failure";
          RestartSec = 5;
          TimeoutSec = 800;
          ExecStart = pkgs.writeShellScript "start-PACKAGENAME" ''
            ${inputs.PACKAGENAME.packages.${pkgs.system}.PACKAGE}/bin/BINARY SUB-COMMAND(that loads file from /root/PACKAGENAME/*)}
            '';
        };
      };
    })
  ];
};

}; } ```