Making and Running Services on Linux using systemd

Once I have set up a project on a server, I typically want it to run all the time, surviving across reboots and restarting if it crashes. To facilitate this, I use systemd, a Linux system manager that enables the use of daemons and other custom background tasks. Below are my notes on how to set up such a system for personal projects.

Guide permalink

First, create a .service file under /etc/systemd/system/. For the sake of this tutorial, we will create one for Minecraft and choose to call it minecraft.service. Services are owned by root, so we must sudo to create the file successfully.

sudo touch /etc/systemd/system/minecraft.service

Each .service file follows the syntax documented here. My typical use requires only a few changes to a base set of contents, so I will provide that template here. Use this template to modify minecraft.service as needed, saving as root. The purpose of each line is described below in comments.

# /etc/systemd/system/minecraft.service

[Unit]
# A description used to identify what this service does.
Description=Run Minecraft
# Ensures that the service doesn't start until after networking has started.
After=network.target

[Service]
# The working directory.
# This should be set to wherever you want to run the task.
# This is typically the directory where the executable lives.
WorkingDirectory=/home/ubuntu/minecraft

# The user and group you want to run this command as.
# Typically, I run commands as my own user (ubuntu) to simplify permissions.
User=ubuntu
Group=ubuntu

# This line ensures the program restarts on its own in case the process crashes.
Restart=always

# The actual command to execute on boot.
# We create a screen instance called mc.
# This will alow us to attach to the screen instance if necessary.
# After that is the command itself.
# In this case, we run a bash script in the working directory.
ExecStart=/usr/bin/screen -DmS mc bash minecraft.sh

[Install]
# The run level.
# Ensures the process starts at the right part of the boot process.
WantedBy=multi-user.target

Now reload systemd so it has access to your new service. This should be run whenever minecraft.service is modified.

sudo systemctl daemon-reload

Enable the service so it will run automatically at boot.

sudo systemctl enable minecraft.service

From here, you can either start the service now with sudo systemctl start minecraft.service or reboot to ensure the service starts properly.

sudo reboot now

After a reboot, you can verify that the command is executing by attaching to its screen instance.

screen -r mc

You can detach from a screen instance by pressing Ctrl+a d. A full cheat sheet of screen commands can be found via this article on Linuxize.

A Short systemctl Cheat Sheet permalink

# Reload the system manager configuration.
# Run this after performing any modifications to a .service file.
sudo systemctl daemon-reload

# Enable the service to run at boot.
sudo systemctl enable minecraft.service

# Disable the service so it no longer runs at boot.
sudo systemctl disable minecraft.service

# Start the service.
# Used if the service is not running.
# This might happen if it was manually stopped
# or if it was never enabled to run at boot.
sudo systemctl start minecraft.service

# Stop the service.
# When Restart=always is used, this command is necessary
# to prevent the killed process from restarting.
sudo systemctl stop minecraft.service

# Equivalent to running stop followed by start.
sudo systemctl restart minecraft.service