Setting Up a Systemd Service

Overview

This guide provides the main points for setting up a systemd service with a working directory, an ExecStart command, and automatic restart functionality.

Steps

1. Create a Systemd Service File

• Location: /etc/systemd/system/<service_name>.service
• Example: /etc/systemd/system/myapp.service

2. Define Service Configuration

In the service file, include the following sections:

[Unit]

• Description: Brief description of the service.
• After: Specify the order of service startup. Commonly network.target for network-dependent services.

[Service]

• WorkingDirectory: The directory from which the service should be executed.
• ExecStart: The command to start the service, usually the path to the executable.
• User: (Optional) The user under which the service will run.
• Restart: Define restart behavior, typically on-failure.
• RestartSec: (Optional) Time to wait before restarting the service after a failure.

[Install]

• WantedBy: Define the target that the service should be attached to, usually multi-user.target.

3. Enable and Start the Service

• Reload systemd: sudo systemctl daemon-reload
• Enable the service: sudo systemctl enable <service_name>.service
• Start the service: sudo systemctl start <service_name>.service

4. Monitoring and Maintenance

• Check status: sudo systemctl status <service_name>.service
• Restart service: sudo systemctl restart <service_name>.service
• View logs: journalctl -u <service_name>.service

Example

Here's an example of a systemd service file for a Node.js application:

[Unit]
Description=Node.js Example App
After=network.target

[Service]
WorkingDirectory=/path/to/nodejs/app
ExecStart=/usr/bin/node /path/to/nodejs/app/app.js
User=nodeuser
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

• WorkingDirectory: This is the directory where your Node.js app resides, e.g., /path/to/nodejs/app.
• ExecStart: This is the command to start your Node.js app, e.g., node app.js.
• Replace /path/to/nodejs/app and nodeuser with the actual path to your application and the username under which it should run.