• Cluster mode: Raft-style leader election, heartbeat-based crash detection, automatic node pruning, cross-node event relay.
• Security: mTLS across all nodes via a shared cluster CA - token-based node joining, per-service certificates.
• Shared database: Pluggable - H2 by default; MySQL, MariaDB, PostgreSQL, MongoDB, or Redis for clusters (MySQL/MariaDB currently blocked by a known issue).
• Service management: Auto-scaling up to each group's minOnline, ordered templates, task-based config patching, live status detection, JAVA and GO service runtimes.
• Group management: Per-group memory, start threshold, static mode, fallback priority, node whitelist, ordered templates.
• Event system: Typed events relayed across the cluster over gRPC.
• Proxy bridge (Velocity): Backend registration, fallback selection, tab-complete relay.
• Addons: sign-system and server-mobs for Bukkit; hub, notify, and proxy for Velocity (proxy also supports Waterfall/BungeeCord).
• Updating: Checks GitHub releases on boot; stages self-updates when general.autoUpdate is enabled or via the update command.

• Velocity: Full support via the bridge plugin plus the hub, notify, and proxy addons. The bridge covers backend registration, fallback selection, initial server, and tab-complete relay.
• Waterfall / BungeeCord: Proxy addon only - animated tab list, MOTD, player count, maintenance mode. Bridge plugin not available yet.
• Bukkit / Spigot: sign-system and server-mobs. Sign-system shows animated server signs; server-mobs adds NPC mobs with live service status.

Run the CLI in a separate terminal and connect to the node:

java -jar polocloud-runner-<version>.jar --cli

connect <token>

The token is in config.json under cluster.cliAccess.registrationToken. On a local setup connect <token> is enough - it assumes localhost.

Multiple nodes form a cluster with cluster join:

cluster join

Every node needs the same shared external database - H2 is single-node only. cluster join only checks for it, it does not set it up. Point localNode.database in config.json at the shared database first:

{
  "localNode": {
    "database": "<shared external database settings>"
  }
}

Then restart the node and run cluster join again. See the cluster architecture for how joining and leader election work.

The Docker guide will help you get started with deploying your PoloCloud in Docker.