Autostop feature (#1212)

Dockerfile

@@ -76,7 +76,8 @@ ENV UID=1000 GID=1000 \
   TYPE=VANILLA VERSION=LATEST \
   ENABLE_RCON=true RCON_PORT=25575 RCON_PASSWORD=minecraft \
   ENABLE_AUTOPAUSE=false AUTOPAUSE_TIMEOUT_EST=3600 AUTOPAUSE_TIMEOUT_KN=120 AUTOPAUSE_TIMEOUT_INIT=600 \
-  AUTOPAUSE_PERIOD=10 AUTOPAUSE_KNOCK_INTERFACE=eth0
+  AUTOPAUSE_PERIOD=10 AUTOPAUSE_KNOCK_INTERFACE=eth0 \
+  ENABLE_AUTOSTOP=false AUTOSTOP_TIMEOUT_EST=3600 AUTOSTOP_TIMEOUT_INIT=1800 AUTOSTOP_PERIOD=10
 
 COPY --chmod=755 scripts/start* /
 COPY --chmod=755 bin/ /usr/local/bin/
@@ -84,8 +85,9 @@ COPY --chmod=755 bin/mc-health /health.sh
 COPY --chmod=644 files/server.properties /tmp/server.properties
 COPY --chmod=644 files/log4j2.xml /tmp/log4j2.xml
 COPY --chmod=755 files/autopause /autopause
+COPY --chmod=755 files/autostop /autostop
 
-RUN dos2unix /start* /autopause/*
+RUN dos2unix /start* /autopause/* /autostop/*
 
 ENTRYPOINT [ "/start" ]
 HEALTHCHECK --start-period=1m CMD mc-health

README.md

@@ -1459,6 +1459,28 @@ The following environment variables define the behaviour of auto-pausing:
 * `AUTOPAUSE_KNOCK_INTERFACE`, default `eth0`
   <br>Describes the interface passed to the `knockd` daemon. If the default interface does not work, run the `ifconfig` command inside the container and derive the interface receiving the incoming connection from its output. The passed interface must exist inside the container. Using the loopback interface (`lo`) does likely not yield the desired results.
 
+## Autostop
+
+An option to stop the server after a specified time has been added for niche applications (e.g. billing saving on AWS Fargate). The function is incompatible with the Autopause functionality, as they basically cancel out each other.
+
+Note that the docker container variables have to be set accordingly (restart policy set to "no") and that the container has to be manually restarted.
+
+A starting, example compose file has been provided in [examples/docker-compose-autostop.yml](examples/docker-compose-autostop.yml).
+
+Enable the Autostop functionality by setting:
+
+```
+-e ENABLE_AUTOSTOP=TRUE
+```
+
+The following environment variables define the behaviour of auto-stopping:
+* `AUTOSTOP_TIMEOUT_EST`, default `3600` (seconds)
+  describes the time between the last client disconnect and the stopping of the server (read as timeout established)
+* `AUTOSTOP_TIMEOUT_INIT`, default `1800` (seconds)
+  describes the time between server start and the stopping of the server, when no client connects inbetween (read as timeout initialized)
+* `AUTOSTOP_PERIOD`, default `10` (seconds)
+  describes period of the daemonized state machine, that handles the stopping of the server
+
 ## Running on RaspberryPi
 
 To run this image on a RaspberryPi 3 B+, 4, or newer, use any of the image tags [list in the Java version section](#running-minecraft-server-on-different-java-version) that specify `armv7` for the architecture, which includes `itzg/minecraft-server:latest`.

examples/docker-compose-autostop.yml

@@ -0,0 +1,20 @@
+version: '3.8'
+
+services:
+  minecraft:
+    image: itzg/minecraft-server
+    ports:
+      - "25565:25565"
+    volumes:
+      - "mc:/data"
+    environment:
+      EULA: "TRUE"
+      ENABLE_AUTOSTOP: "TRUE"
+      # More aggressive settings for demo purposes
+      AUTOSTOP_TIMEOUT_INIT: "30"
+      AUTOSTOP_TIMEOUT_EST: "20"
+    # Important not to auto-restart the server!!!
+    restart: "no"
+
+volumes:
+  mc: {}

files/autostop/autostop-daemon.sh

@@ -0,0 +1,69 @@
+#!/bin/bash
+
+# needed for the clients connected function residing in autopause
+. /autopause/autopause-fcns.sh
+
+. ${SCRIPTS:-/}start-utils
+
+# wait for java process to be started
+while :
+do
+  if java_process_exists ; then
+    break
+  fi
+  sleep 0.1
+done
+
+STATE=INIT
+
+while :
+do
+  case X$STATE in
+  XINIT)
+    # Server startup
+    if mc_server_listening ; then
+      TIME_THRESH=$(($(current_uptime)+$AUTOSTOP_TIMEOUT_INIT))
+      logAutostop "MC Server listening for connections - stopping in $AUTOSTOP_TIMEOUT_INIT seconds"
+      STATE=II
+    fi
+    ;;
+  XII)
+    # Initial idle
+    if java_clients_connected ; then
+      logAutostop "Client connected - waiting for disconnect"
+      STATE=E
+    else
+      if [[ $(current_uptime) -ge $TIME_THRESH ]] ; then
+        logAutostop "No client connected since startup - stopping server"
+        /autostop/stop.sh
+        exit 0
+      fi
+    fi
+    ;;
+  XE)
+    # Established
+    if ! java_clients_connected ; then
+      TIME_THRESH=$(($(current_uptime)+$AUTOSTOP_TIMEOUT_EST))
+      logAutostop "All clients disconnected - stopping in $AUTOSTOP_TIMEOUT_EST seconds"
+      STATE=I
+    fi
+    ;;
+  XI)
+    # Idle
+    if java_clients_connected ; then
+      logAutostop "Client reconnected - waiting for disconnect"
+      STATE=E
+    else
+      if [[ $(current_uptime) -ge $TIME_THRESH ]] ; then
+        logAutostop "No client reconnected - stopping"
+        /autostop/stop.sh
+        exit 0
+      fi
+    fi
+    ;;
+  *)
+    logAutostop "Error: invalid state: $STATE"
+    ;;
+  esac
+  sleep $AUTOSTOP_PERIOD
+done

files/autostop/stop.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+. /start-utils
+
+logAutostopAction "Stopping Java process"
+kill -SIGTERM 1

scripts/start-autostop

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+# shellcheck source=start-utils
+. "${SCRIPTS:-/}start-utils"
+
+: "${SERVER_PORT:=25565}"
+export SERVER_PORT
+
+log "Autostop functionality enabled"
+
+isDebugging && set -x
+
+if ! [[ $AUTOSTOP_PERIOD =~ ^[0-9]+$ ]]; then
+  AUTOSTOP_PERIOD=10
+  export AUTOSTOP_PERIOD
+  log "Warning: AUTOSTOP_PERIOD is not numeric, set to 10 (seconds)"
+fi
+if [ "$AUTOSTOP_PERIOD" -eq "0" ] ; then
+  AUTOSTOP_PERIOD=10
+  export AUTOSTOP_PERIOD
+  log "Warning: AUTOSTOP_PERIOD must not be 0, set to 10 (seconds)"
+fi
+if ! [[ $AUTOSTOP_TIMEOUT_EST =~ ^[0-9]+$ ]] ; then
+  AUTOSTOP_TIMEOUT_EST=3600
+  export AUTOSTOP_TIMEOUT_EST
+  log "Warning: AUTOSTOP_TIMEOUT_EST is not numeric, set to 3600 (seconds)"
+fi
+if ! [[ $AUTOSTOP_TIMEOUT_INIT =~ ^[0-9]+$ ]] ; then
+  AUTOSTOP_TIMEOUT_INIT=1800
+  export AUTOSTOP_TIMEOUT_INIT
+  log "Warning: AUTOSTOP_TIMEOUT_INIT is not numeric, set to 1800 (seconds)"
+fi
+
+/autostop/autostop-daemon.sh &

scripts/start-configuration

@@ -37,6 +37,11 @@ if isTrue "${ENABLE_AUTOPAUSE}" && isTrue "${EXEC_DIRECTLY:-false}"; then
     exit 1
 fi
 
+if isTrue "${ENABLE_AUTOPAUSE}" && isTrue "${ENABLE_AUTOSTOP}"; then
+    log "ENABLE_AUTOPAUSE=true is incompatible with ENABLE_AUTOSTOP=true"
+    exit 1
+fi
+
 if [[ $PROXY ]]; then
     export http_proxy="$PROXY"
     export https_proxy="$PROXY"
@@ -96,6 +101,10 @@ if isTrue "${ENABLE_AUTOPAUSE}"; then
   ${SCRIPTS:-/}start-autopause
 fi
 
+if isTrue "${ENABLE_AUTOSTOP}"; then
+  ${SCRIPTS:-/}start-autostop
+fi
+
 if versionLessThan 1.7; then
   echo "
 MC_HEALTH_EXTRA_ARGS=(

scripts/start-utils

@@ -93,6 +93,14 @@ function logAutopauseAction() {
   echo "[$(date -Iseconds)] [Autopause] $*"
 }
 
+function logAutostop() {
+  echo "[Autostop loop] $*"
+}
+
+function logAutostopAction() {
+  echo "[$(date -Iseconds)] [Autostop] $*"
+}
+
 function normalizeMemSize() {
   local scale=1
   case ${1,,} in