Create a systemd Service

Introduction

systemd is the init system used by most modern Linux distributions (Ubuntu, Debian, CentOS, Fedora, etc.). It manages system services, handling everything from starting services at boot to monitoring their status.

Service Unit Files

Service unit files define how systemd should manage a service. They’re stored in /etc/systemd/system/ for user-created services.

Basic Structure

[Unit]
Description=My Application Service
After=network.target

[Service]
Type=simple
User=learner
WorkingDirectory=/home/learner
ExecStart=/usr/bin/python3 /home/learner/myapp.py
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Sections Explained

[Unit]

• Description - Human-readable description
• After - Start after these units

[Service]

• Type - Service type (simple, forking, oneshot, etc.)
• User - Run as this user
• WorkingDirectory - Set working directory
• ExecStart - Command to start the service
• Restart - When to restart (always, on-failure, etc.)
• RestartSec - Seconds to wait before restart

[Install]

• WantedBy - Target that wants this service

Managing Services with systemctl

# Reload systemd after adding/modifying unit files
$ sudo systemctl daemon-reload

# Enable service (start on boot)
$ sudo systemctl enable myapp

# Start service now
$ sudo systemctl start myapp

# Enable and start in one command
$ sudo systemctl enable --now myapp

# Check service status
$ sudo systemctl status myapp

# Stop service
$ sudo systemctl stop myapp

# Restart service
$ sudo systemctl restart myapp

# View logs
$ sudo journalctl -u myapp -f

Your Task

A Python application is provided at /home/learner/myapp.py. Create a systemd service that:

1. Runs the application as the learner user
2. Starts automatically on boot
3. Restarts if it crashes
4. Listens on port 5000

Steps

1. Create the unit file at /etc/systemd/system/myapp.service
2. Reload systemd configuration
3. Enable the service
4. Start the service
5. Verify it’s running with curl http://localhost:5000

Template

Use this as your starting point:

[Unit]
Description=My Python App
After=network.target

[Service]
Type=simple
User=learner
WorkingDirectory=/home/learner
ExecStart=/usr/bin/python3 /home/learner/myapp.py
Restart=always
RestartSec=3

[Install]
WantedBy=multi-user.target

Launch Your Sandbox

Copy the command below to start this exercise: