Autopause functionality (#531)

files/autopause/autopause-daemon.sh

@@ -0,0 +1,97 @@
+#!/bin/bash
+
+exec 1>/tmp/terminal-mc
+
+. /autopause/autopause-fcns.sh
+
+sudo /usr/sbin/knockd -c /autopause/knockd-config.cfg -d
+if [ $? -ne 0 ] ; then
+  while :
+  do
+    if [[ -n $(ps -o comm | grep java) ]] ; then
+      break
+    fi
+    sleep 0.1
+  done
+  echo "[Autopause loop] Failed to start knockd daemon."
+  echo "[Autopause loop] Possible cause: docker's host network mode."
+  echo "[Autopause loop] Recreate without host mode or disable autopause functionality."
+  echo "[Autopause loop] Stopping server."
+  killall -SIGTERM java
+  exit 1
+fi
+
+STATE=INIT
+
+while :
+do
+  case X$STATE in
+  XINIT)
+    # Server startup
+    if mc_server_listening ; then
+      TIME_THRESH=$(($(current_uptime)+$AUTOPAUSE_TIMEOUT_INIT))
+      echo "[Autopause loop] MC Server listening for connections - stopping in $AUTOPAUSE_TIMEOUT_INIT seconds"
+      STATE=K
+    fi
+    ;;
+  XK)
+    # Knocked
+    if java_clients_connected ; then
+      echo "[Autopause loop] Client connected - waiting for disconnect"
+      STATE=E
+    else
+      if [[ $(current_uptime) -ge $TIME_THRESH ]] ; then
+        echo "[Autopause loop] No client connected since startup / knocked - stopping"
+        /autopause/pause.sh
+        STATE=S
+      fi
+    fi
+    ;;
+  XE)
+    # Established
+    if ! java_clients_connected ; then
+      TIME_THRESH=$(($(current_uptime)+$AUTOPAUSE_TIMEOUT_EST))
+      echo "[Autopause loop] All clients disconnected - stopping in $AUTOPAUSE_TIMEOUT_EST seconds"
+      STATE=I
+    fi
+    ;;
+  XI)
+    # Idle
+    if java_clients_connected ; then
+      echo "[Autopause loop] Client reconnected - waiting for disconnect"
+      STATE=E
+    else
+      if [[ $(current_uptime) -ge $TIME_THRESH ]] ; then
+        echo "[Autopause loop] No client reconnected - stopping"
+        /autopause/pause.sh
+        STATE=S
+      fi
+    fi
+    ;;
+  XS)
+    # Stopped
+    if rcon_client_exists ; then
+      /autopause/resume.sh
+    fi
+    if java_running ; then
+      if java_clients_connected ; then
+        echo "[Autopause loop] Client connected - waiting for disconnect"
+        STATE=E
+      else
+        TIME_THRESH=$(($(current_uptime)+$AUTOPAUSE_TIMEOUT_KN))
+        echo "[Autopause loop] Server was knocked - waiting for clients or timeout"
+        STATE=K
+      fi
+    fi
+    ;;
+  *)
+    echo "[Autopause loop] Error: invalid state: $STATE"
+    ;;
+  esac
+  if [[ "$STATE" == "S" ]] ; then
+    # before rcon times out
+    sleep 2
+  else
+    sleep $AUTOPAUSE_PERIOD
+  fi
+done

files/autopause/autopause-fcns.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+current_uptime() {
+  echo $(awk '{print $1}' /proc/uptime | cut -d . -f 1)
+}
+
+java_running() {
+  [[ $( ps -a -o stat,comm | grep 'java' | awk '{ print $1 }') =~ ^S.*$ ]]
+}
+
+rcon_client_exists() {
+  [[ -n "$(ps -a -o comm | grep 'rcon-cli')" ]]
+}
+
+mc_server_listening() {
+  [[ -n $(netstat -tln | grep "0.0.0.0:$SERVER_PORT" | grep LISTEN) ]]
+}
+
+java_clients_connected() {
+  local connections
+  connections=$(netstat -tn | grep ":$SERVER_PORT" | grep ESTABLISHED)
+  if [[ -z "$connections" ]] ; then
+    return 1
+  fi
+  IFS=$'\n'
+  connections=($connections)
+  unset IFS
+  # check that at least one external address is not localhost
+  # remember, that the host network mode does not work with autopause because of the knockd utility
+  for (( i=0; i<${#connections[@]}; i++ ))
+  do
+    if [[ ! $(echo "${connections[$i]}" | awk '{print $5}') =~ ^\s*127\.0\.0\.1:.*$ ]] ; then
+      # not localhost
+      return 0
+    fi
+  done
+  return 1
+}

files/autopause/knockd-config.cfg

@@ -0,0 +1,12 @@
+[options]
+ logfile = /dev/null
+[unpauseMCServer-server]
+ sequence = 25565
+ seq_timeout = 1
+ command = /sbin/su-exec minecraft:minecraft /autopause/resume.sh
+ tcpflags = syn
+[unpauseMCServer-rcon]
+ sequence = 25575
+ seq_timeout = 1
+ command = /sbin/su-exec minecraft:minecraft /autopause/resume.sh
+ tcpflags = syn

files/autopause/pause.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+if [[ $( ps -a -o stat,comm | grep 'java' | awk '{ print $1 }') =~ ^S.*$ ]] ; then
+  # save world
+  rcon-cli save-all >/dev/null
+
+  # wait until mc-monitor is no longer connected to the server
+  while :
+  do
+    if [[ -z "$(netstat -nt | grep "127.0.0.1:$SERVER_PORT" | grep 'ESTABLISHED')" ]]; then
+      break
+    fi
+    sleep 0.1
+  done
+
+  # finally pause the process
+  echo "[$(date -Iseconds)] [Autopause] Pausing Java process" >/tmp/terminal-mc
+  killall -q -STOP java
+fi

files/autopause/resume.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+if [[ $( ps -a -o stat,comm | grep 'java' | awk '{ print $1 }') =~ ^T.*$ ]] ; then
+  echo "[$(date -Iseconds)] [Autopause] Knocked, resuming Java process" >/tmp/terminal-mc
+  killall -q -CONT java
+fi

files/sudoers-mc

@@ -0,0 +1,2 @@
+%minecraft ALL=(ALL) NOPASSWD:/usr/bin/killall
+%minecraft ALL=(ALL) NOPASSWD:/usr/sbin/knockd