Stop paying for empty Minecraft servers

AutoStopper puts idle Docker-based backends to sleep and wakes them the moment a player connects through Velocity. Players keep using your network normally. You stop running servers nobody is playing on.

Install it on Velocity, list the containers you want managed, and let quiet servers sleep.

Why you will like it

• It wakes servers for you. A player picks a sleeping server through normal Velocity routing. AutoStopper starts the container and connects them as soon as it is ready. No client mod, no replacement /server command.
• It waits for Minecraft, not just Docker. A running container is not a ready server. AutoStopper waits for a real Minecraft status reply, Docker health, or either one, with a bounded deadline on every probe and command.
• It handles the rush back in. If ten players arrive at once they share one start and are connected together when the server answers.
• It only touches what you map. Hubs, lobbies and anything not listed in monitored_servers are never started, stopped or intercepted.
• It fails clearly. Failed stops retry with capped backoff and never pretend the server stopped. An invalid reload keeps the previous configuration running. Players see short, friendly messages; raw Docker output stays in your logs.

What your players see

Quick start

1. Pick a complete, pinned example and copy it: Java 21 / Velocity 3.5.1, Java 25 / Velocity 4.2 (recommended), or Java 25 / Velocity 4.2.1 preview.

2. Put the downloaded, unchanged JAR in velocity_server/plugins/AutoStopper.jar.

3. Start the stack once, then edit velocity_server/plugins/autostopper/config.yml.

4. Map each Velocity server name to its existing Docker container:

   monitored_servers:
     - server_name: survival
       container_name: survival-server
   

5. Restart Velocity or run /autostopper reload, then check /autostopper status.

Managed containers must already exist and use restart: "no", otherwise Docker can undo a successful idle stop. Leave always-on servers out of monitored_servers.

Docker security warning. The tested install mounts /var/run/docker.sock into Velocity. Access to that socket is effectively root on the Docker host, and adding the proxy user to the socket group is not ordinary non-root isolation. Prefer a dedicated host or VM, install only trusted plugins, and read the security guidance first.

Sensible defaults

Setting	Default
Inactivity timeout	5 minutes
Readiness	Minecraft status reply, 120 second overall deadline
Automatic stop attempts	3, with 60 to 300 second capped backoff
Plugin shutdown deadline	10 seconds
Managed servers	none until you add mappings

Every value is configurable and validated as one atomic snapshot. See the configuration reference.

Commands

Command	Permission
/autostopper, /as	Everyone
/autostopper help	Everyone, filtered to what you can use
/autostopper status [server]	autostopper.command.status
/autostopper start, stop, restart <server>	autostopper.command.start, .stop, .restart
/autostopper hold, release <server>	autostopper.command.hold, .release
/autostopper reload	autostopper.command.reload

autostopper.admin grants all of them. AutoStopper never replaces Velocity's /server command.

Tested support

One Java 21 JAR is tested on five complete runtime lines. Keep the proxy image and Velocity build from one row together.

Line	Proxy image	Java	Velocity
Legacy (minimum)	itzg/mc-proxy:2026.8.0-java21	21	3.5.1 build 615
Stable 4.0 (production)	itzg/mc-proxy:2026.8.0-java25	25	4.0.0 build 6
Stable 4.1 (production)	itzg/mc-proxy:2026.8.0-java25	25	4.1.0 build 22
Stable 4.2 (recommended)	itzg/mc-proxy:2026.8.0-java25	25	4.2.0 build 30
Preview (snapshot)	itzg/mc-proxy:2026.8.0-java25	25	4.2.1-SNAPSHOT build 41

Velocity 4 needs Java 25. The preview line tracks a PaperMC snapshot and is not a production baseline. The full release candidate runs against a real Purpur 1.21.4 backend with actual protocol clients, simultaneous joins, idle stop, restart, never-ready servers and failed-stop retry. Minecraft versions 1.7.2 through 26.2 are listed because AutoStopper uses only Velocity events and a generic status request, but only that backend is exercised directly.

Help and docs

• Troubleshooting covers every failure outcome you can see in chat or logs
• Configuration reference
• Security guidance
• Migrating from 1.1.2 to 2.0.0
• Full installation guide
• Changelog
• Report an issue

Ready to let empty servers sleep? Pick an example, review the Docker security boundary, and install the same validated JAR that is published on GitHub Releases.