How to Manage Java Applications as Services on Linux?

Managing Java Applications as Services on Linux

In the realm of server administration, managing applications as services ensures their reliable operation and ease of control. For Java applications deployed on Linux systems, this article explores the options available to turn them into services and effectively manage their execution.

The Challenge

Starting and stopping a Java application on a Linux server often involves modifying the rc.local script. However, this approach lacks the ability to control the application independently and can be inconvenient for updates or troubleshooting.

Creating a Linux Service

To overcome these limitations, Linux systems provide the concept of services, managed through tools like init.d or systemd. These services allow you to start, stop, and restart applications at will, independent of server restarts.

Creating a Service for a Java Application

1. Define a Service Script: Create a shell script with the following format:

<code class="sh">#!/bin/sh
SERVICE_NAME=WebServer
PATH_TO_JAR=/path/to/WebServer.jar

case  in
    start)
        echo "Starting $SERVICE_NAME ..."
        nohup java -jar $PATH_TO_JAR &
    ;;
    stop)
        echo "Stopping $SERVICE_NAME ..."
        kill $(cat /tmp/WebServer-pid)
        rm /tmp/WebServer-pid
    ;;
    restart)
        <pre class="brush:php;toolbar:false"><code class="sh">chmod +x /usr/local/bin/WebServer</code>

<code class="sh">cp /usr/local/bin/WebServer /etc/init.d/WebServer
ln -s /etc/init.d/WebServer /etc/rc?.d/S99WebServer</code>

2. Configure Permissions: Set the script's permissions to allow execution:

<code class="sh">[Unit]
Description=Web Server Service
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/WebServer start
ExecStop=/usr/local/bin/WebServer stop
Restart=on-failure
StandardOutput=syslog
StandardError=syslog

[Install]
WantedBy=multi-user.target</code>

3. Install the Service: Depending on your Linux distribution and service management system, you may have different steps.

• init.d (Legacy): Copy the script to /etc/init.d/ and create a symbolic link to /etc/rc?.d/:

• systemd (Modern): Create a unit file in /lib/systemd/system/:

Starting, Stopping, and Restarting the Service

To control the service, use the following commands:

• Start: service WebServer start
• Stop: service WebServer stop
• Restart: service WebServer restart

Additional Features

• Provide Logging: Modify the ExecStart and ExecStop lines in the unit file to specify log files for the service.
• Configure Dependencies: Add After and Before directives in the unit file to specify dependencies on other services.
• Create a Plesk Extension: For Plesk users, package the wrapper script as a Plesk extension to manage the service from the Plesk interface.

By following these steps, you can effectively manage your Java applications as Linux services, gaining the flexibility and control to ensure their reliable operation and timely maintenance.

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