Add autoscaling documentation and examples for mc-router integration (#3826)

docs/misc/autoscale/autoscale.md

@@ -0,0 +1,39 @@
+
+# Autoscaling (sleep when idle)
+
+Autoscaling (sometimes called *sleeping*, *scale to zero* or *wake on join*) is the pattern of stopping a Minecraft server when nobody is playing and starting it again when someone tries to connect with the intention of saving resources when the server is not in use (e.g., on a VPS with limited CPU/RAM or a home server).
+
+## mc-router
+
+[mc-router](https://github.com/itzg/mc-router) is a Minecraft-aware router/multiplexer.
+
+- Routes players by the hostname they connect with (useful for multiple servers behind one port)
+- Can auto-start a backend container on join and stop it again after an idle timeout
+
+Examples:
+
+- See the mc-router section in [Examples](../examples.md#mc-router-with-auto-scale)
+
+## Lazymc
+
+[Lazymc](https://github.com/timvisee/lazymc) can keep a server “asleep” until a player connects. With Docker it’s commonly used via [lazymc-docker-proxy](https://github.com/joesturge/lazymc-docker-proxy).
+
+- Players connect to the proxy; the proxy starts/stops the server container
+- Usually requires a static IP for the Minecraft container on a user-defined network
+
+Example:
+
+- See the Lazymc section in [Examples](../examples.md#lazymc-put-your-minecraft-server-to-rest-when-idle)
+
+## Lazytainer
+
+[Lazytainer](https://github.com/vmorganp/Lazytainer) starts/stops containers based on network traffic.
+
+- Uses packet thresholds + inactivity timeouts (not Minecraft hostname aware)
+- Can be triggered by port scans/pings in noisy environments
+
+Example:
+
+- See the Lazytainer section in [Examples](../examples.md#lazytainer-stop-minecraft-container-based-on-traffic)
+
+

docs/misc/examples.md

@@ -27,6 +27,48 @@ services:
 
 [Source](https://github.com/itzg/docker-minecraft-server/blob/master/examples/geyser/docker-compose.yml)
 
+
+## mc-router with auto-scale
+
+Using [mc-router](https://github.com/itzg/mc-router) in front of one or multiple Minecraft server containers allows you to route players based on the hostname they use to connect.
+
+With `AUTO_SCALE_UP` and `AUTO_SCALE_DOWN` enabled, mc-router can automatically start a target server when a player connects and stop it again after a period of inactivity.
+
+```yaml title="compose.yaml"
+services:
+  router:
+    image: itzg/mc-router
+    environment:
+      IN_DOCKER: true
+      AUTO_SCALE_DOWN: true
+      AUTO_SCALE_UP: true
+      AUTO_SCALE_DOWN_AFTER: 2h
+      AUTO_SCALE_ASLEEP_MOTD: "Server is asleep. Join again to wake it up!"
+    ports:
+      - "25565:25565"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+
+  vanilla:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+    labels:
+      mc-router.host: "vanilla.example.com"
+
+  paper:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      TYPE: PAPER
+    labels:
+      mc-router.host: "paper.example.com"
+```
+
+[Source](https://github.com/itzg/mc-router/blob/main/examples/docker-autoscale/compose-minimal.yml)
+
+[More detailed example](https://github.com/itzg/mc-router/blob/main/examples/docker-autoscale/compose.yml)
+
 ## Lazymc - Put your Minecraft server to rest when idle
 
 With [lazymc-docker-proxy](https://github.com/joesturge/lazymc-docker-proxy) you are able to use [lazymc](https://github.com/timvisee/lazymc) with the minecraft container.

examples/mc-router-autoscale/compose-minimal.yml

@@ -0,0 +1,27 @@
+# Source: https://github.com/itzg/mc-router/blob/main/examples/docker-autoscale/compose-minimal.yml
+services:
+  router:
+    image: itzg/mc-router
+    environment:
+      IN_DOCKER: true
+      AUTO_SCALE_DOWN: true
+      AUTO_SCALE_UP: true
+      AUTO_SCALE_DOWN_AFTER: 2h
+      AUTO_SCALE_ASLEEP_MOTD: "Server is asleep. Join again to wake it up!"
+    ports:
+      - "25565:25565"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+  vanilla:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+    labels:
+      mc-router.host: "vanilla.example.com"
+  paper:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      TYPE: PAPER
+    labels:
+      mc-router.host: "paper.example.com"

examples/mc-router-autoscale/compose.yml

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+# Source: https://github.com/itzg/mc-router/blob/main/examples/docker-autoscale/compose.yml
+# This is a verbose example with comments and explanations for configuring auto-scaling behavior
+# for Docker backend servers. See compose-minimal.yml for a simple minimal example.
+services:
+  router:
+    image: itzg/mc-router
+    environment:
+      IN_DOCKER: true
+      # Global auto-scaling settings for all docker-backend servers
+      # Settings can be overridden per-backend using labels
+      # as shown in the backend services below (except for AUTO_SCALE_DOWN_AFTER which is global only)
+      # Enable auto-scaling down after inactivity for all backends by default
+      AUTO_SCALE_DOWN: true
+      # Enable auto-scaling up after player join for all backends by default
+      AUTO_SCALE_UP: true
+      # Time of inactivity after which to scale down (default: 10m) - Global only setting
+      AUTO_SCALE_DOWN_AFTER: 2h
+      # MOTD to show when server is asleep (default: empty string - don't show MOTD, show server offline instead)
+      AUTO_SCALE_ASLEEP_MOTD: "Server is asleep. Join again to wake it up!"
+    ports:
+      - "25565:25565"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+  vanilla:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+    labels:
+      # If global auto scaling settings are enabled, this backend will
+      # auto-scale without any additional auto-scale related configuration
+      mc-router.host: "vanilla.example.com"
+  fabric:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      TYPE: FABRIC
+    labels:
+      mc-router.host: "fabric.example.com"
+      # Disable auto-scaling for this backend specifically
+      mc-router.auto-scale-up: false
+      mc-router.auto-scale-down: false
+  paper:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      TYPE: PAPER
+    labels:
+      mc-router.host: "paper.example.com"
+      # Override asleep MOTD for this backend
+      mc-router.auto-scale-asleep-motd: "Paper is folded. Join to unfold!"