Run a Java Application as a Service on Linux

Question

I have written a Java server application that runs on a standard virtual hosted Linux solution. The application runs all the time listening for socket connections and creating new handlers for them. It is a server side implementation to a client-server application.

The way I start it is by including it in the start up rc.local script of the server. However once started I do not know how to access it to stop it and if I want to install an update, so I have to restart the server in order to restart the application.

On a windows PC, for this type of application I might create a windows service and then I can stop and start it as I want. Is there anything like that on a Linux box so that if I start this application I can stop it and restart it without doing a complete restart of the server.

My application is called WebServer.exe. It is started on server startup by including it in my rc.local as such:

java -jar /var/www/vhosts/myweb.com/phpserv/WebServer.jar &

I am a bit of a noob at Linux so any example would be appreciated with any posts. However I do have SSH, and full FTP access to the box to install any updates as well as access to a Plesk panel.

Answer 1

To run Java code as daemon (service) you can write JNI based stub.

http://jnicookbook.owsiak.org/recipe-no-022/

for a sample code that is based on JNI. In this case you daemonize the code that was started as Java and main loop is executed in C. But it is also possible to put main, daemon's, service loop inside Java.

https://github.com/mkowsiak/jnicookbook/tree/master/recipeNo029

Have fun with JNI!

Answer 2

Linux service init script are stored into /etc/init.d. You can copy and customize /etc/init.d/skeleton file, and then call

service [yourservice] start|stop|restart

see http://www.ralfebert.de/blog/java/debian_daemon/. Its for Debian (so, Ubuntu as well) but fit more distribution.

Answer 3

From Spring Boot Reference Guide

Installation as an init.d service (System V)

Simply symlink the jar to init.d to support the standard start, stop, restart and status commands. Assuming that you have a Spring Boot application installed in /var/myapp, to install a Spring Boot application as an init.d service simply create a symlink:

$ sudo ln -s /var/myapp/myapp.jar /etc/init.d/myapp

Once installed, you can start and stop the service in the usual way. For example, on a Debian based system:

$ service myapp start

If your application fails to start, check the log file written to /var/log/<appname>.log for errors.

Continue reading to know how to secure a deployed service.

After doing as written I've discovered that my service fails to start with this error message in logs: start-stop-daemon: unrecognized option --no-close. And I've managed to fix it by creating a config file /var/myapp/myapp.conf with the following content

USE_START_STOP_DAEMON=false

Answer 4

From Spring Boot application as a Service, I can recommend the Python-based supervisord application. See that stack overflow question for more information. It's really straightforward to set up.

Answer 5

A simple solution is to create a script start.sh that runs Java through nohup and then stores the PID to a file:

nohup java -jar myapplication.jar > log.txt 2> errors.txt < /dev/null &
PID=$!
echo $PID > pid.txt

Then your stop script stop.sh would read the PID from the file and kill the application:

PID=$(cat pid.txt)
kill $PID

Of course I've left out some details, like checking whether the process exists and removing pid.txt if you're done.

Answer 6

Referring to Spring Boot application as a Service as well, I would go for the systemd version, since it's the easiest, least verbose, and best integrated into modern distros (and even the not-so-modern ones like CentOS 7.x).