SLS is a declarative orchestration system for ephemeral game servers, designed especially for server networks. Everything in SLS is reproducible, isolated, and fully defined through Blueprints.

SLS runs every game server inside its own Docker container, keeping environments clean, consistent and secure.

SLS is free and open-source software licensed under AGPL-3.0.

Protocube

Protocube is the core controller for SLS, responsible for managing all server instances across the system. It provides a REST API for creating, managing, and monitoring servers.

Docs:

• API Docs (Coming Soon)
• Plugin Docs (Coming Soon)
• Setup (Coming Soon)

Daemon

The server control plane for SLS. Each Daemon is responsible for provisioning, controlling and monitoring servers inside isolated Docker containers, exactly as defined by their Blueprints.

S4J

A Java wrapper for the Protocube API, providing a clean interface for plugins and external tools.

Blueprints

Blueprints are declarative specifications describing exactly how a game server should run: its software, world, version, limits, configuration patches, and bundled content.

Below is a full example Blueprint.

# Blueprint metadata
blueprint:
  id: "blueprint"                # Unique slug ID
  name: "Blueprint Name"         # Human-readable name
  type: "game"                   # Arbitrary grouping tag

# Declarative server state
# Volumes are managed storage units.
# All volume sources are resolved relative to the sls
# configured volumes directory (e.g. /sls/volumes).
#
# Volumes cannot escape this directory and are never arbitrary host paths.
state:
  volumes:
    # Primary server filesystem
    - name: "world"
      source: "worlds/world"     # Resolved to /sls/volumes/worlds/world
      mount: "/world"            # Mount point inside the container
      mode: cow                  # cow | ro | rw (default: cow)

    # Read-only plugins or assets
    - name: "plugins"
      source: "plugins"
      mount: "/plugins"
      mode: ro

    # Example persistent data volume
    # (useful for databases, player data, etc.)
    - name: "data"
      source: "shared/data"
      mount: "/data"
      mode: rw

# Server runtime configuration
# The server base files are automatically installed or pre-installed
# at /servers/<software>/<version> (or custom path).
server:
  software: "platform"
  version: "1.0.0"
  image: "sls:java_21"

  # optional override
  # path: "custom/path"

  # Resource limits applied to the container
  limits:
    memory_limit: 4096           # MB
    swap: 1024                   # MB
    io_weight: 500
    cpu_limit: 200               # Percentage (200 = 2 cores)
    disk_space: 5120             # MB
    threads: ""
    oom_disabled: false

  # Configuration patches applied at startup
  configs:
    server.properties:
      parser: properties
      find:
        motd: "Blueprint Server"

# Explicit host mounts
# These mount arbitrary host paths directly into the container.
# They must be explicitly allowed in the daemon configuration.
# (ro = read-only) omit to allow writing to files
mounts:
  - /host/path:/home/container:ro

# Copy files into server filesystem at creation
# - Files inside the SLS folder can always be copied
# - Files outside the SLS folder require the source path to be listed in the daemon's allowed_mounts
# Destinations are always relative to the server filesystem
copy:
  - sls/files/config.yml:plugins/config.yml

# Whether servers created from this blueprint persist after shutdown.
# If false, the server instance and all non-persistent volume state
# are destroyed when the server stops.
save: false

# Arbitrary metadata for external systems
annotations:
  maintainer: "Maintainer"
  tags: ["game", "example"]

Development Status

Warning

This version of SLS is in active development and is not yet ready for use.

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