Server-In-Server

A Velocity plugin that launches and manages Minecraft server instances as child processes directly from the proxy. Configure servers in a single YAML file — the plugin handles starting, stopping, auto-restarting, port assignment, and proxy registration automatically.

How it works

When Velocity starts, the plugin reads plugins/server-in-server/config.yml. For each configured server with auto-start: true, it spawns a new Java process running the specified server jar, generates server.properties with the correct port, optionally accepts the EULA, registers the server in Velocity's proxy, and adds it to velocity.toml. If a server crashes, the plugin can auto-restart it a configurable number of times.

Quick start

1. Place the plugin jar in plugins/
2. Start Velocity — the plugin creates plugins/server-in-server/config.yml with a default config
3. Edit config.yml to match your server jars and settings
4. Run /sis reload in the Velocity console to apply changes

Configuration

Global settings

auto-eula: false
lobby-server: "lobby"

| Field | Default | Description |
|---|---|---|
| auto-eula | false | If true, creates eula.txt with eula=true automatically for every server. If false, you must accept the EULA manually. |
| lobby-server | "" | Server name to connect players to when they first join the proxy. Leave empty to disable. |

Server entries

servers:
  - name: "lobby"
    jar: "servers/lobby/server.jar"
    directory: "servers/lobby"
    port: 0
    flags: "-Xmx1G -Xms512M"
    auto:
      start: true
      restart: true
      retry-count: 0
    stop:
      command: "stop"
      wait-to-stop: true
      wait: 10

| Field | Default | Description |
|---|---|---|
| name | — | Server name used in Velocity and for routing |
| jar | — | Path to the server jar (relative to the proxy directory, or absolute) |
| directory | "servers/<name>" | Working directory for the server process |
| port | 0 | Server port. 0 = auto-assign (velocityPort + 2 + index) |
| flags | "-Xmx1G -Xms512M" | JVM arguments passed to java before -jar |
| auto.start | true | Start this server when Velocity (re)starts |
| auto.restart | false | Restart the server automatically when it stops/crashes |
| auto.retry-count | 0 | Max restart attempts. 0 = infinite restarts |
| stop.command | "stop" | Command sent via stdin to gracefully stop the server |
| stop.wait-to-stop | true | If true, wait for the process to exit before force killing |
| stop.wait | 10 | Seconds to wait before force killing (only if wait-to-stop is true) |

Commands

All commands use the /sis prefix and can be run from the Velocity console or by players with appropriate permissions.

| Command | Description |
|---|---|
| /sis start <server> | Start a configured server |
| /sis stop <server> | Gracefully stop a running server |
| /sis restart <server> | Stop then start a server |
| /sis forcestop | Kill all child processes and shut down Velocity |
| /sis reload | Reload config, stop all servers, start auto-start ones |
| /sis list | Show all configured servers with their status and ports |
| /sis com <server> <command> | Send a console command to a running server |

Port auto-assignment

If port is 0, the plugin calculates it as:

port = velocityBindPort + 2 + serverIndex

Where serverIndex is the server's position in the servers list (0-based).

Example with Velocity on port 25565:

| Index | Server | Calculated port |
|---|---|---|
| 0 | lobby | 25567 |
| 1 | survival | 25568 |
| 2 | creative | 25569 |

velocity.toml integration

On every startup and reload, the plugin scans velocity.toml for the [servers] section and adds or updates entries for all configured servers. Existing entries for other servers are preserved. If the [servers] section does not exist, it is created at the end of the file.

Requirements

• Java 21+
• Velocity 3.5.0-SNAPSHOT (or compatible 3.x)