{
  description = "i2pd-exporter devshell, service and options";

  # Nixpkgs / NixOS version to use.
  inputs.nixpkgs.url = "nixpkgs/nixos-unstable";

  outputs = { self, nixpkgs }:
    let
      #version = builtins.substring 0 8 self.lastModifiedDate;

      # System types to support.
      supportedSystems =
        [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];

      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;

      nixpkgsFor = forAllSystems (system: import nixpkgs {
        inherit system;
      });

    in
    {

      packages = forAllSystems (system:
        let
          pkgs = nixpkgsFor.${system};
        in
        {
          default = pkgs.rustPlatform.buildRustPackage {
            pname = "i2pd-exporter";
            version = "0.1.1";
            src = ./.;

            nativeBuildInputs = with pkgs; [
              pkg-config
              openssl
            ];
            buildInputs = with pkgs; [
              pkg-config
              openssl
            ];
            cargoLock.lockFile = ./Cargo.lock;
          };
        });

      nixosModules.default = { config, lib, pkgs, ... }:
        with lib;
        let
          cfg = config.services.prometheus.exporters.i2pd;
        in
        {
          options.services.prometheus.exporters.i2pd = {

            enable = mkEnableOption "Enable the i2pd exporter";

            listenAddress = mkOption {
              type = types.str;
              default = "127.0.0.1";
            };

            port = mkOption {
              type = types.port;
              default = 5733;
            };

            routerAddress = mkOption {
              type = types.str;
              default = "http://127.0.0.1:7650";
            };

            openFirewall = mkOption {
              type = types.bool;
              default = false;
              description = lib.mdDoc ''
                Open the appropriate ports in the firewall for i2pd-exporter.
              '';
            };

            routerPassword = mkOption {
              type = types.str;
              default = "itoopie";
            };
          };


          config = mkIf cfg.enable {
            systemd.services.i2pd-exporter = {
              description = "Exporter for i2pd";
              wantedBy = [ "multi-user.target" ];
              environment = {
                IP = cfg.listenAddress;
                PORT = toString cfg.port;

                ROUTER = cfg.routerAddress;
                PASSWORD = cfg.routerPassword;
              };

              serviceConfig = {
                DynamicUser = "yes";
                ExecStart = "${self.packages.${pkgs.system}.default}/bin/i2pd-exporter";
                Restart = "on-failure";
                RestartSec = "5s";
              };
            };

            networking.firewall =
              mkIf cfg.openFirewall { allowedTCPPorts = [ cfg.port ] ++ optional (cfg.listenAddress != "127.0.0.1") cfg.port; };

          };
        };
      devShells.default =
        with nixpkgs; mkShell
          {
            LIBCLANG_PATH = "${pkgs.llvmPackages_17.libclang.lib}/lib";
            RUST_BACKTRACE = 1;
            RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";

            packages = with pkgs; [
              rustc
              cargo
              rustfmt
              rust-analyzer
              clippy
              rustup
              pkg-config
              openssl
            ];
          };
    };
}