nixos/metis: add minecraft (MSD)

nixos/configurations/metis/default.nix

@@ -7,6 +7,7 @@
 {
   imports = [
     ./wireguard.nix
+    ./minecraft
   ];
   nixpkgs.hostPlatform = "x86_64-linux";
   nix.registry.sys = {

nixos/configurations/metis/minecraft/default.nix

@@ -0,0 +1,13 @@
+{ pkgs, ... }:
+{
+  imports = [
+    ./msd.nix
+  ];
+
+  lib.pkgs = {
+    authlib-injector = pkgs.fetchurl {
+      url = "https://github.com/yushijinhun/authlib-injector/releases/download/v1.2.4/authlib-injector-1.2.4.jar";
+      hash = "sha256-eVsnbLQIVe0E3H/KvCptFQ3kYAtUKHWmUi5l9rJbyp8=";
+    };
+  };
+}

nixos/configurations/metis/minecraft/msd.nix

@@ -0,0 +1,48 @@
+{ config, pkgs, ... }:
+let
+  name = "modernskyblock";
+  serviceName = "minecraft-${name}";
+  directory = "minecraft/${name}";
+  stdin = "/run/${directory}/stdin";
+
+  # https://github.com/NixOS/nixpkgs/blob/6e62521155cd3b4cdf6b49ecacf63db2a0cacc73/nixos/modules/services/games/minecraft-server.nix#L25C3-L34C1
+  stopScript = pkgs.writeShellScript "minecraft-server-stop" ''
+    echo stop > ${stdin}
+
+    # Wait for the PID of the minecraft server to disappear before
+    # returning, so systemd doesn't attempt to SIGKILL it.
+    while kill -0 "$1" 2> /dev/null; do
+      sleep 1s
+    done
+  '';
+
+in
+{
+  systemd.services.${serviceName} = {
+    after = [ "systemd-networkd-wait-online.service" ];
+    description = "Minecraft Server (Modern Skyblock 3: Departed)";
+    requires = [ "${serviceName}.socket" ];
+    serviceConfig = rec {
+      Type = "simple";
+      DynamicUser = true;
+      StateDirectory = directory;
+      WorkingDirectory = "%S/${directory}";
+      ExecStart = "${pkgs.jdk8}/bin/java -Xmx32G -Xms32G -javaagent:${config.lib.pkgs.authlib-injector}=https://hitmc.cc/api/yggdrasil -jar forge-1.12.2-14.23.5.2808-universal.jar nogui";
+      ExecStop = "${stopScript} $MAINPID";
+      Restart = "always";
+      StandardInput = "socket";
+      StandardOutput = "journal";
+      StandardError = "journal";
+    };
+  };
+
+  systemd.sockets.${serviceName} = {
+    description = "Socket for the Minecraft Server (Modern Skyblock 3: Departed)";
+    wantedBy = [ "sockets.target" ];
+    socketConfig = {
+      ListenFIFO = stdin;
+      RemoveOnStop = true;
+      FlushPending = true;
+    };
+  };
+}