Minecraft Bedrock Server NixOS module

minecraft-bedrock-server.nix

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

let

  libCrypto = with pkgs; stdenv.mkDerivation rec {
    name = "${pname}-${version}";
    pname = "minecraft-bedrock-server-libcrypto";
    version = "1.16-201.02";
    src = fetchurl {
      url = "https://minecraft.azureedge.net/bin-linux/bedrock-server-1.16.201.02.zip";
      sha256 = "7213784b7d321044fee0ae89c781a3a3cd189dbfcb4911a959f11ee8a876b0cb";
    };
    sourceRoot = ".";
    nativeBuildInputs = [
      autoPatchelfHook
      curl
      gcc-unwrapped
      openssl
      unzip
    ];
    installPhase = ''
      install -m755 -D libCrypto.so  $out/lib/libCrypto.so
    '';
    fixupPhase = ''
      autoPatchelf $out/lib/libCrypto.so
    '';
  };

  minecraft-bedrock-server = with pkgs; stdenv.mkDerivation rec {
    name = "${pname}-${version}";
    pname = "minecraft-bedrock-server";
    version = "1.16-201.02";
    src = fetchurl {
      url = "https://minecraft.azureedge.net/bin-linux/bedrock-server-1.16.201.02.zip";
      sha256 = "7213784b7d321044fee0ae89c781a3a3cd189dbfcb4911a959f11ee8a876b0cb";
    };
    sourceRoot = ".";
    nativeBuildInputs = [
      (patchelf.overrideDerivation(old: {
        postPatch = ''
          substituteInPlace src/patchelf.cc \
            --replace "32 * 1024 * 1024" "512 * 1024 * 1024"
        '';
      }))
      autoPatchelfHook
      curl
      gcc-unwrapped
      libCrypto
      openssl
      unzip
    ];
    installPhase = ''
      install -m755 -D bedrock_server $out/bin/bedrock_server
      rm bedrock_server
      rm libCrypto.so
      rm server.properties
      mkdir -p $out/var
      cp -a . $out/var/lib
    '';
    fixupPhase = ''
      autoPatchelf $out/bin/bedrock_server
    '';
  };

in

with lib;

let
  cfg = config.services.minecraft-bedrock-server;

  cfgToString = v: if builtins.isBool v then boolToString v else toString v;

  serverPropertiesFile = pkgs.writeText "server.properties" (''
    # server.properties managed by NixOS configuration
  '' + concatStringsSep "\n" (mapAttrsToList
    (n: v: "${n}=${cfgToString v}") cfg.serverProperties));

  defaultServerPort = 19132;

  serverPort = cfg.serverProperties.server-port or defaultServerPort;

in {
  options = {
    services.minecraft-bedrock-server = {

      enable = mkOption {
        type = types.bool;
        default = false;
        description = ''
          If enabled, start a Minecraft Bedrock Server. The server
          data will be loaded from and saved to
          <option>services.minecraft-bedrock-server.dataDir</option>.
        '';
      };

      dataDir = mkOption {
        type = types.path;
        default = "/var/lib/minecraft-bedrock";
        description = ''
          Directory to store Minecraft Bedrock database and other state/data files.
        '';
      };

      serverProperties = mkOption {
        type = with types; attrsOf (oneOf [ bool int str ]);
        default = {
            server-name = "Dedicated Server";
            gamemode = "survival";
            difficulty = "easy";
            allow-cheats = false;
            max-players = 10;
            online-mode = false;
            white-list = false;
            server-port = 19132;
            server-portv6 = 19133;
            view-distance = 32;
            tick-distance = 4;
            player-idle-timeout = 30;
            max-threads = 8;
            level-name = "Bedrock level";
            level-seed = "";
            default-player-permission-level = "member";
            texturepack-required = false;
            content-log-file-enabled = false;
            compression-threshold = 1;
            server-authoritative-movement = "server-auth";
            player-movement-score-threshold = 20;
            player-movement-distance-threshold = 0.3;
            player-movement-duration-threshold-in-ms = 500;
            correct-player-movement = false;
        };
        example = literalExample ''
          {
            server-name = "Dedicated Server";
            gamemode = "survival";
            difficulty = "easy";
            allow-cheats = false;
            max-players = 10;
            online-mode = false;
            white-list = false;
            server-port = 19132;
            server-portv6 = 19133;
            view-distance = 32;
            tick-distance = 4;
            player-idle-timeout = 30;
            max-threads = 8;
            level-name = "Bedrock level";
            level-seed = "";
            default-player-permission-level = "member";
            texturepack-required = false;
            content-log-file-enabled = false;
            compression-threshold = 1;
            server-authoritative-movement = "server-auth";
            player-movement-score-threshold = 20;
            player-movement-distance-threshold = 0.3;
            player-movement-duration-threshold-in-ms = 500;
            correct-player-movement = false;
          }
        '';
        description = ''
          Minecraft Bedrock server properties for the server.properties file.
        '';
      };

      package = mkOption {
        type = types.package;
        default = minecraft-bedrock-server;
        defaultText = "pkgs.minecraft-bedrock-server";
        example = literalExample "pkgs.minecraft-bedrock-server-1_16";
        description = "Version of minecraft-bedrock-server to run.";
      };

    };
  };

  config = mkIf cfg.enable {

    users.users.minecraft = {
      description     = "Minecraft server service user";
      home            = cfg.dataDir;
      createHome      = true;
      uid             = config.ids.uids.minecraft;
    };

    systemd.services.minecraft-bedrock-server = {
      description   = "Minecraft Bedrock Server Service";
      wantedBy      = [ "multi-user.target" ];
      after         = [ "network.target" ];

      serviceConfig = {
        ExecStart = "${cfg.package}/bin/bedrock_server";
        Restart = "always";
        User = "minecraft";
        WorkingDirectory = cfg.dataDir;
      };

      preStart = ''
        cp -a -n ${cfg.package}/var/lib/* .
        cp -f ${serverPropertiesFile} server.properties
        chmod +w server.properties
      '';
    };

    networking.firewall = {
      allowedUDPPorts = [ serverPort ];
    };
  };
}