Tutorial:Server startup script

Systemd Script

Installation

[Unit]
Description=Minecraft Server %i
After=network.target

[Service]
WorkingDirectory=/opt/minecraft/%i

# Solves the issue where the minecraft server will endlessly restart itself
# See https://askubuntu.com/questions/953920/systemctl-service-timed-out-during-start for more info
Type=simple

PrivateUsers=true
# Users Database is not available from within the unit, only root and minecraft is available, everybody else is nobody

User=minecraft
Group=minecraft

ProtectSystem=full
# Read only mapping of /usr /boot and /etc

ProtectHome=true
# /home, /root and /run/user seem to be empty from within the unit. It is recommended to enable this setting for all long-running services (in particular network-facing ones).

ProtectKernelTunables=true
# /proc/sys, /sys, /proc/sysrq-trigger, /proc/latency_stats, /proc/acpi, /proc/timer_stats, /proc/fs and /proc/irq will be read-only within the unit. It is recommended to turn this on for most services.
# Implies MountFlags=slave

ProtectKernelModules=true
# Block module system calls, also /usr/lib/modules. It is recommended to turn this on for most services that do not need special file systems or extra kernel modules to work
# Implies NoNewPrivileges=yes

ProtectControlGroups=true
# It is hence recommended to turn this on for most services.
# Implies MountAPIVFS=yes

# Set default memory values
Environment="MCMINMEM=512M" "MCMAXMEM=1024M" "SHUTDOWN_DELAY=5" "POST_SHUTDOWN_DELAY=10"
# Change memory values in environment file
EnvironmentFile=-/opt/minecraft/%i/server.conf

# Uncomment this to fix screen on RHEL 8
#ExecStartPre=+/bin/sh -c 'chmod 777 /run/screen'

ExecStart=/bin/sh -c \
'find -L . \
-maxdepth 1 \
-type f \
-iregex ".*/\\(FTBServer\\|craftbukkit\\|spigot\\|paper\\|forge\\|minecraft_server\\).*jar" \
-print0 \
-quit \
| xargs -0 -I{} \
/usr/bin/screen -DmS mc-%i \
/usr/bin/java \
-server \
-Xms${MCMINMEM} \
-Xmx${MCMAXMEM} \
-XX:+UseG1GC \
-XX:ParallelGCThreads=2 \
-XX:MinHeapFreeRatio=5 \
-XX:MaxHeapFreeRatio=10 \
-jar {} \
--nogui'

# Alternative to the above ExecStart. Found to work better as this creates the screen session prior to invoking java to run the server.
# Solves the problem many encountered when starting the service where it would fail with the error 'no screen session found'.
ExecStartPre=/bin/sh -c \
'find -L . \
-maxdepth 1 \
-type f \
-iregex ".*/\\(FTBServer\\|craftbukkit\\|spigot\\|paper\\|forge\\|minecraft_server\\).*jar" \
-print0 \
-quit \
| xargs -0 -I{} \
/usr/bin/screen -DmS mc-%i'
ExecStart=/bin/sh -c \
'/usr/bin/java \
-server \
-Xms${MCMINMEM} \
-Xmx${MCMAXMEM} \
-XX:+UseG1GC \
-XX:ParallelGCThreads=2 \
-XX:MinHeapFreeRatio=5 \
-XX:MaxHeapFreeRatio=10 \
-jar {} \ # insert server jar name. i.e. 'server.jar'
 --nogui' 

# Simplified of alternative
ExecStartPre=/bin/sh -c '/usr/bin/screen -dmS mc-%i'
ExecStart=/bin/sh -c '/usr/bin/java -server -Xmx${MCMAXMEM} -Xms${MCMINMEM} -jar server.jar --nogui'

ExecReload=/usr/bin/screen -p 0 -S mc-%i -X eval 'stuff "reload"\\015'

ExecStop=/usr/bin/screen -p 0 -S mc-%i -X eval 'stuff "say SERVER SHUTTING DOWN. Saving map..."\\015'
ExecStop=/bin/sh -c '/bin/sleep ${SHUTDOWN_DELAY}'
ExecStop=/usr/bin/screen -p 0 -S mc-%i -X eval 'stuff "save-all"\\015'
ExecStop=/usr/bin/screen -p 0 -S mc-%i -X eval 'stuff "stop"\\015'
ExecStop=/bin/sh -c '/bin/sleep ${POST_SHUTDOWN_DELAY}'

Restart=on-failure
RestartSec=60s

[Install]
WantedBy=multi-user.target

#########
# HowTo
#########
#
# Create a directory in /opt/minecraft/XX where XX is a name like 'survival'
# Add minecraft_server.jar into dir with other conf files for minecraft server
#
# Enable/Start systemd service
# systemctl enable minecraft@survival
# systemctl start minecraft@survival
#
# To run multiple servers simply create a new dir structure and enable/start it
# systemctl enable minecraft@creative
# systemctl start minecraft@creative
#
# To change specific server memory assignment, create file /opt/minecraft/XX/server.conf (where XX is your server name) and add below lines:
# MCMINMEM=512M
# MCMAXMEM=2048M

Setup Instance

Start/Stop Instances

Autostart

Enable

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Init.d Script

Pre-Requisites

Download

#!/bin/bash
# /etc/init.d/minecraft
# version 0.4.2 2016-02-09 (YYYY-MM-DD)
#
### BEGIN INIT INFO
# Provides: minecraft
# Required-Start: $local_fs $remote_fs screen-cleanup
# Required-Stop: $local_fs $remote_fs
# Should-Start: $network
# Should-Stop: $network
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Minecraft server
# Description: Starts the minecraft server
### END INIT INFO

#Settings
SERVICE='minecraft_server.jar'
SCREENNAME='minecraft_server'
OPTIONS='--nogui'
USERNAME='minecraft'
WORLD='world'
MCPATH='/home/minecraft'
BACKUPPATH='/minecraft/minecraft.backup'
MAXHEAP=2048
MINHEAP=1024
HISTORY=1024
CPU_COUNT=1
INVOCATION="java -Xmx${MAXHEAP}M -Xms${MINHEAP}M -XX:+UseConcMarkSweepGC \
 -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=$CPU_COUNT -XX:+AggressiveOpts \
 -jar $SERVICE$OPTIONS"

ME=`whoami`
as_user(){
if["$ME"="$USERNAME"];then
bash-c"$1"
else
su-"$USERNAME"-c"$1"
fi
}

mc_start(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is already running!"
else
echo"Starting $SERVICE..."
cd$MCPATH
as_user"cd $MCPATH && screen -h $HISTORY -dmS ${SCREENNAME}$INVOCATION"
sleep7
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is now running."
else
echo"Error! Could not start $SERVICE!"
fi
fi
}

mc_saveoff(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is running... suspending saves"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"say SERVER BACKUP STARTING. Server going readonly...\"\015'"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"save-off\"\015'"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"save-all\"\015'"
sync
sleep10
else
echo"$SERVICE is not running. Not suspending saves."
fi
}

mc_saveon(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is running... re-enabling saves"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"save-on\"\015'"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"say SERVER BACKUP ENDED. Server going read-write...\"\015'"
else
echo"$SERVICE is not running. Not resuming saves."
fi
}

mc_stop(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"Stopping $SERVICE"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"say SERVER SHUTTING DOWN IN 10 SECONDS. Saving map...\"\015'"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"save-all\"\015'"
sleep10
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"stop\"\015'"
sleep7
else
echo"$SERVICE was not running."
fi
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"Error! $SERVICE could not be stopped."
else
echo"$SERVICE is stopped."
fi
}

mc_update(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is running! Will not start update."
else
as_user"cd $MCPATH && wget -q -O $MCPATH/versions --no-check-certificate https://piston-meta.mojang.com/mc/game/version_manifest.json"
if["$1"=="snapshot"];then
JSONVERSION=`cd$MCPATH&&catversions|python-c"exec(\"import json,sys\nobj=json.load(sys.stdin)\nversion=obj['latest']['snapshot']\nfor v in obj['versions']:\n if v['id']==version:\n print(v['url'])\")"`
else
JSONVERSION=`cd$MCPATH&&catversions|python-c"exec(\"import json,sys\nobj=json.load(sys.stdin)\nversion=obj['latest']['release']\nfor v in obj['versions']:\n if v['id']==version:\n print(v['url'])\")"`
fi
as_user"cd $MCPATH && wget -q -O $MCPATH/versions --no-check-certificate $JSONVERSION"
MC_SERVER_URL=`cd$MCPATH&&catversions|python-c'import json,sys;obj=json.load(sys.stdin);print(obj["downloads"]["server"]["url"])'`
as_user"rm $MCPATH/versions"
as_user"cd $MCPATH && wget -q -O $MCPATH/minecraft_server.jar.update --no-check-certificate $MC_SERVER_URL"
if[-f$MCPATH/minecraft_server.jar.update];then
if`diff$MCPATH/$SERVICE$MCPATH/minecraft_server.jar.update>/dev/null`;then
echo"You are already running the latest version of $SERVICE."
else
as_user"mv $MCPATH/minecraft_server.jar.update $MCPATH/$SERVICE"
echo"Minecraft successfully updated."
fi
else
echo"Minecraft update could not be downloaded."
fi
fi
}

mc_backup(){
mc_saveoff

NOW=`date"+%Y-%m-%d_%Hh%M"`
BACKUP_FILE="$BACKUPPATH/${WORLD}_${NOW}.tar"
echo"Backing up minecraft world..."
#as_user "cd $MCPATH && cp -r $WORLD $BACKUPPATH/${WORLD}_`date "+%Y.%m.%d_%H.%M"`"
as_user"tar -C \"$MCPATH\" -cf \"$BACKUP_FILE\" $WORLD"

echo"Backing up $SERVICE"
as_user"tar -C \"$MCPATH\" -rf \"$BACKUP_FILE\" $SERVICE"
#as_user "cp \"$MCPATH/$SERVICE\" \"$BACKUPPATH/minecraft_server_${NOW}.jar\""

mc_saveon

echo"Compressing backup..."
as_user"gzip -f \"$BACKUP_FILE\""
echo"Done."
}

mc_command(){
command="$1";
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
pre_log_len=`wc-l"$MCPATH/logs/latest.log"|awk'{print $1}'`
echo"$SERVICE is running... executing command"
as_user"screen -p 0 -S ${SCREENNAME} -X eval 'stuff \"$command\"\015'"
sleep.1# assumes that the command will run and print to the log file in less than .1 seconds
# print output
tail-n$((`wc-l"$MCPATH/logs/latest.log"|awk'{print $1}'`-$pre_log_len))"$MCPATH/logs/latest.log"
fi
}

mc_listen(){
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
as_user"tail -f $MCPATH/logs/latest.log"
else
echo"$SERVICE is not running. Cannot listen to server."
fi
}


#Start-Stop here
case"$1"in
start)
mc_start
;;
stop)
mc_stop
;;
restart)
mc_stop
mc_start
;;
update)
mc_stop
mc_backup
mc_update$2
mc_start
;;
backup)
mc_backup
;;
status)
ifpgrep-u$USERNAME-f$SERVICE>/dev/null;then
echo"$SERVICE is running."
else
echo"$SERVICE is not running."
fi
;;
command)
if[$#-gt1];then
shift
mc_command"$*"
else
echo"Must specify server command (try 'help'?)"
fi
;;
listen)
mc_listen
;;

*)
echo"Usage: $0 {start|stop|update|backup|status|restart|command \"server command\"}"
exit1
;;
esac

exit0

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