Post summary: Code snippet how to start Java application as a Linux service.
The code below can be found in GitHub sample-dropwizard-rest-stub repository in linux_service_file file. This post is related to Build a RESTful stub server with Dropwizard post. REST server builds there is being set up to run as Linux service with the code snippet shown below.
Service snippet
This snippet can be used for other applications to be run as Linux service, not only Java.
#!/bin/bash
BASE_DIR=/var/dropwizard-rest-stub
START_COMMAND="java -jar $BASE_DIR/dropwizard-rest-stub.jar server $BASE_DIR/config.yml"
PID_FILE=$BASE_DIR/dropwizard-rest-stub.pid
LOG_DIR=$BASE_DIR/logs
start() {
PID=`$START_COMMAND > $LOG_DIR/init.log 2>$LOG_DIR/init.error.log & echo $!`
}
case "$1" in
start)
if [ -f $PID_FILE ]; then
PID=`cat $PID_FILE`
if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
start
else
echo "Already running [$PID]"
exit 0
fi
else
start
fi
if [ -z $PID ]; then
echo "Failed starting"
exit 1
else
echo $PID > $PID_FILE
echo "Started [$PID]"
exit 0
fi
;;
status)
if [ -f $PID_FILE ]; then
PID=`cat $PID_FILE`
if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
echo "Not running (process dead but PID file exists)"
exit 1
else
echo "Running [$PID]"
exit 0
fi
else
echo "Not running"
exit 0
fi
;;
stop)
if [ -f $PID_FILE ]; then
PID=`cat $PID_FILE`
if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
echo "Not running (process dead but PID file exists)"
rm -f $PID_FILE
exit 1
else
PID=`cat $PID_FILE`
kill -term $PID
echo "Stopped [$PID]"
rm -f $PID_FILE
exit 0
fi
else
echo "Not running (PID not found)"
exit 0
fi
;;
restart)
$0 stop
$0 start
;;
*)
echo "Usage: $0 {status|start|stop|restart}"
exit 0
esac
Install as a Linux service
In order to make it a Linux service following file has to be copied into /etc/init.d/ Linux folder with the name that you want your service to be. If you want your service to be named service_name then you put the same name as filename: /etc/init.d/service_name.
Nota bene: If you are creating the service and copying the file from Windows machine it has different new line endings (CR + LF) than Linux (LF). Also by default Git amends line endings on a pull and push depending on the OS. If you receive message: env: /etc/init.d/service_name: No such file or directory then you have to replace CR+LF to LF only. This can be done with following command: sed -i -e ‘s/\r//g’ /etc/init.d/service_name.
Manage service
Assume you have named your file dropwizard then you manage your service with that name. Service has 4 commands: status, start, stop and restart. You start the service with service dropwizard start command. If you input something different than 4 options given above service will output its usage pattern.
Conclusion
In current post I have provided sample bash script that is used to install Java or any other application as a Linux service and then start, stop or restart it.
