CurseForge Server Updater

A lightweight Bash script that keeps your CurseForge modpack server up-to-date automatically.
No Docker required. Works with any server manager.

What it does

When you run it, this script:

1. Checks the CurseForge API for a new server pack release
2. Skips silently if you're already on the latest version
3. Backs up your world and key configs before touching anything
4. Downloads the new server pack via the authenticated CurseForge API
5. Stops your server (via Crafty, systemd, screen, or tmux)
6. Applies the update : overwriting mods and configs, never your world
7. Restarts the server; mods re-download automatically on first boot

Works with any CurseForge modpack that publishes a server pack file (All of Create, ATM, Vault Hunters, FTB, etc.).

Requirements

Tool	Purpose
bash >= 4	Script runtime
curl	CurseForge API + download
unzip	Extract server pack
rsync	Apply files while skipping preserved items
python3	Parse API JSON responses

All standard on Debian/Ubuntu. Install any missing:

sudo apt install curl unzip rsync python3

Getting a CurseForge API Key

You need a free CurseForge API key — takes under 2 minutes.

1. Go to console.curseforge.com and sign in.
2. In the left sidebar, click API Keys.
3. Click Generate API Key and give it a name (e.g. mc-server).
4. Copy the key immediately - it's only shown once.

Free tier: 10,000 requests/day, more than enough for daily checks.

Finding Your Project ID

Open the modpack page on CurseForge. The Project ID is in the About panel on the right side of the page.

Installation

git clone https://github.com/AzLeCurieux/curseforge-server-updater.git
cd curseforge-server-updater
chmod +x update-modpack.sh

# Pick the right template:
cp .env.example .env             # systemd, screen, or tmux
# or
cp .env.example.crafty .env      # Crafty Controller

nano .env
chmod 600 .env

Configuration

All settings live in .env. Minimum required:

CF_API_KEY=your_api_key_here
CF_PROJECT_ID=1518930
SERVER_DIR=/opt/minecraft/server
SERVER_MANAGER=systemd

Full .env reference

CurseForge

Variable	Required	Description
CF_API_KEY	yes	Your CurseForge API key
CF_PROJECT_ID	yes	Modpack project ID
CF_GAME_VERSION	yes	Minecraft version (e.g. 1.21.1)

Server

Variable	Default	Description
SERVER_DIR	yes	Absolute path to your server directory
PRESERVE_ITEMS	see below	Comma-separated files/folders to never overwrite
SERVER_USER		OS user that owns server files (for permission fix)

Default preserved items:

world, server.properties, whitelist.json, ops.json,
banned-players.json, banned-ips.json, eula.txt,
server.jar, user_jvm_args.txt

Server Manager

Variable	Default	Description
SERVER_MANAGER	none	crafty | systemd | screen | tmux | none
STOP_WAIT_SECONDS	15	Seconds to wait after stop command
SYSTEMD_SERVICE		Service name (if systemd)
SCREEN_SESSION		Session name (if screen)
TMUX_SESSION		Session name (if tmux)

Crafty Controller

Variable	Description
CRAFTY_URL	Crafty base URL, e.g. https://127.0.0.1:8443
CRAFTY_USER	Crafty admin username
CRAFTY_PASS	Crafty admin password
CRAFTY_SERVER_ID	Server UUID (from Crafty UI or database)

Backup

Variable	Default	Description
RUN_BACKUP_BEFORE	false	Create a backup before updating
BACKUP_DIR	./backups	Where to save automatic backups
BACKUP_SCRIPT		Path to a custom backup script

Notifications

Variable	Description
DISCORD_WEBHOOK	Discord webhook URL for update notifications

Usage

# Check only, nothing is changed
./update-modpack.sh --check
# exit 0 = up to date  |  exit 1 = update available

# Check and apply the update
sudo ./update-modpack.sh

Example output:

2026-05-07 10:00:01  INFO  CurseForge Server Updater - project 1518930
2026-05-07 10:00:01  INFO  Installed server pack ID: 6601234
2026-05-07 10:00:02  INFO  Querying CurseForge API...
2026-05-07 10:00:02  INFO  Latest available: All of Create Aeronautics - v1.4 (ID: 6669879)
2026-05-07 10:00:02  INFO  Updating: 6601234 -> 6669879 (All of Create Aeronautics - v1.4)
2026-05-07 10:00:03  INFO  Running backup script...
2026-05-07 10:00:45  INFO  Backup saved: pre-update-2026-05-07_10-00-03.tar.gz (118MB)
2026-05-07 10:00:45  INFO  Getting download URL...
2026-05-07 10:00:46  INFO  Downloading: https://edge.forgecdn.net/files/...
2026-05-07 10:00:49  INFO  Downloaded: 7.9M
2026-05-07 10:00:49  INFO  Stopping server (manager: crafty)...
2026-05-07 10:01:05  INFO  Extracting server pack...
2026-05-07 10:01:05  INFO  Applying update...
2026-05-07 10:01:05  INFO  Clearing old mods/ directory...
2026-05-07 10:01:06  INFO  Files updated.
2026-05-07 10:01:06  INFO  Patching variables.txt...
2026-05-07 10:01:06  INFO  Starting server (manager: crafty)...
2026-05-07 10:01:07  INFO  Update complete: All of Create Aeronautics - v1.4
2026-05-07 10:01:07  INFO  Note: mods will be re-downloaded by ServerStarterJar on next startup.

Automating with cron

sudo crontab -e

# Check and apply modpack updates every day at 04:00
0 4 * * * /path/to/curseforge-server-updater/update-modpack.sh >> /var/log/mc-updater.log 2>&1

Check-only (alert via Discord, update manually):

0 4 * * * /path/to/curseforge-server-updater/update-modpack.sh --check

How the update works

The script queries the CurseForge API for the latest server pack file ID. If it differs from what's stored in .installed-version, it downloads the pack (typically 7-15 MB), stops the server, clears the mods/ directory, and rsyncs the new files while skipping anything in PRESERVE_ITEMS. On next startup, the server launcher (ServerStarterJar or equivalent) re-downloads the actual mod JARs from CurseForge CDN.

Why only ~8 MB? Modern packs ship a lightweight bootstrap: a manifest + small launcher JAR. The mods (~300-600 MB) download on first boot. That's also why mods/ gets cleared on each update — to force the launcher to fetch the correct new versions.

Crafty Controller

Use .env.example.crafty as your starting point.

Finding your Server UUID:

From the Crafty URL:

https://your-crafty:8443/panel/server_detail?id=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

Or from the terminal:

sqlite3 /path/to/crafty/config/db/crafty.sqlite \
  "SELECT server_uuid, server_name FROM servers;"

See docs/crafty-setup.md for the full Crafty guide.

ServerStarterJar & variables.txt

Many CurseForge server packs use ServerStarterJar to bootstrap the server. Each update ships a new variables.txt that can reset settings you customized.

Use VARS_PATCHES in .env to re-apply your settings after every update:

VARS_PATCHES=SKIP_JAVA_CHECK=true
JAVA="/usr/bin/java"
SERVERSTARTERJAR_FORCE_FETCH=false
WAIT_FOR_USER_INPUT=false

Discord Notifications

Set DISCORD_WEBHOOK in .env:

DISCORD_WEBHOOK=https://discord.com/api/webhooks/YOUR_WEBHOOK_URL

You'll get a message when a new version is found, when an update completes, or when an error occurs.

Comparison with docker-minecraft-server

	docker-minecraft-server	This script
Requires Docker	yes	no
Works with Crafty Controller	no	yes
Works with systemd / screen / tmux	no	yes
Standalone (no image rebuild)	no	yes
Custom backup before update	no	yes
Discord notifications	no	yes
Update check only (--check)	no	yes

Use itzg/docker-minecraft-server if you run a pure Docker setup. Use this script if you manage your server with Crafty, systemd, or any other non-Docker tool.

Troubleshooting

No server pack found
The modpack may not publish a server pack. Check the modpack's Files page for an entry labeled "Server Pack".

Could not get download URL
Your CF_API_KEY may be invalid or expired. Regenerate it at console.curseforge.com.

Update re-applies every run
The .installed-version file is missing. Run once without --check to create it, or set it manually:

echo "CURSEFORGE_FILE_ID" > .installed-version

Mods not downloading on startup
Check that WAIT_FOR_USER_INPUT=false and RESTART=false are set in variables.txt.

Permission denied on server files
Run with sudo, or set SERVER_USER in .env.

Contributing

Issues and PRs welcome. When reporting a bug, include your SERVER_MANAGER value, relevant log lines, and the modpack project ID.

License

MIT © 2026 AzLeCurieux