nixpkgs/nixos/modules/services/misc/redlib.nix

{
  config,
  lib,
  pkgs,
  ...
}:

let
  inherit (lib)
    concatStringsSep
    mkEnableOption
    mkIf
    mkOption
    mkPackageOption
    mkRenamedOptionModule
    types
    ;

  cfg = config.services.redlib;

  args = concatStringsSep " " ([
    "--port ${toString cfg.port}"
    "--address ${cfg.address}"
  ]);
in
{
  imports = [
    (mkRenamedOptionModule
      [
        "services"
        "libreddit"
      ]
      [
        "services"
        "redlib"
      ]
    )
  ];

  options = {
    services.redlib = {
      enable = mkEnableOption "Private front-end for Reddit";

      package = mkPackageOption pkgs "redlib" { };

      address = mkOption {
        default = "0.0.0.0";
        example = "127.0.0.1";
        type = types.str;
        description = "The address to listen on";
      };

      port = mkOption {
        default = 8080;
        example = 8000;
        type = types.port;
        description = "The port to listen on";
      };

      openFirewall = mkOption {
        type = types.bool;
        default = false;
        description = "Open ports in the firewall for the redlib web interface";
      };

    };
  };

  config = mkIf cfg.enable {
    systemd.services.redlib = {
      description = "Private front-end for Reddit";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" ];
      serviceConfig = {
        DynamicUser = true;
        ExecStart = "${lib.getExe cfg.package} ${args}";
        AmbientCapabilities = lib.mkIf (cfg.port < 1024) [ "CAP_NET_BIND_SERVICE" ];
        Restart = "on-failure";
        RestartSec = "2s";

        # Hardening
        CapabilityBoundingSet = if (cfg.port < 1024) then [ "CAP_NET_BIND_SERVICE" ] else [ "" ];
        DeviceAllow = [ "" ];
        LockPersonality = true;
        MemoryDenyWriteExecute = true;
        PrivateDevices = true;
        # A private user cannot have process capabilities on the host's user
        # namespace and thus CAP_NET_BIND_SERVICE has no effect.
        PrivateUsers = (cfg.port >= 1024);
        ProcSubset = "pid";
        ProtectClock = true;
        ProtectControlGroups = true;
        ProtectHome = true;
        ProtectHostname = true;
        ProtectKernelLogs = true;
        ProtectKernelModules = true;
        ProtectKernelTunables = true;
        ProtectProc = "invisible";
        RestrictAddressFamilies = [
          "AF_INET"
          "AF_INET6"
        ];
        RestrictNamespaces = true;
        RestrictRealtime = true;
        RestrictSUIDSGID = true;
        SystemCallArchitectures = "native";
        SystemCallFilter = [
          "@system-service"
          "~@privileged"
          "~@resources"
        ];
        UMask = "0077";
      };
    };

    networking.firewall = mkIf cfg.openFirewall {
      allowedTCPPorts = [ cfg.port ];
    };
  };

  meta = {
    maintainers = with lib.maintainers; [ Guanran928 ];
  };
}