How to create systemd services for Linux

Create a service specific user

For security it is best to run a service with a specific user and group. You can create one using the following command:

sudo adduser --system  --gecos "Deluge Service" --disabled-password --group --home /var/lib/deluge deluge
usermod -u 2114 deluge
groupmod -g 2122 deluge
chmod -R deluge:deluge /var/lib/deluge

This creates a new system user and group named deluge with no login access and home directory /var/lib/deluge which will be the default location for the config files.

In addition you can add to the deluge group any users you wish to be able to easily manage or access files downloaded by Deluge, for example:

sudo adduser <username> deluge

Daemon (deluged) service

Create the file /etc/systemd/system/deluged.service containing the following:

[Unit]
Description=Deluge Bittorrent Client Daemon
Documentation=man:deluged
After=network-online.target

[Service]
Type=simple
UMask=007

ExecStart=/usr/bin/deluged -d

Restart=on-failure

# Time to wait before forcefully stopped.
TimeoutStopSec=300

[Install]
WantedBy=multi-user.target

sudo mkdir /etc/systemd/system/deluged.service.d/

# Override service user
[Service]
User=deluge
Group=deluge

sudo systemctl enable /etc/systemd/system/deluged.service
sudo systemctl start deluged
sudo systemctl status deluged

Web UI (deluge-web) service

Create the file /etc/systemd/system/deluge-web.service containing the following:

[Unit]
Description=Deluge Bittorrent Client Web Interface
Documentation=man:deluge-web
After=network-online.target deluged.service
Wants=deluged.service

[Service]
Type=simple
UMask=027

ExecStart=/usr/bin/deluge-web -d

Restart=on-failure

[Install]
WantedBy=multi-user.target

sudo mkdir /etc/systemd/system/deluge-web.service.d/

# Override service user
[Service]
User=deluge
Group=deluge

sudo systemctl enable /etc/systemd/system/deluge-web.service
sudo systemctl start deluge-web
sudo systemctl status deluge-web

Service logging

Create a log directory for Deluge and give the service user (e.g. deluge), full access:

sudo mkdir -p /var/log/deluge
sudo chown -R deluge:deluge /var/log/deluge
sudo chmod -R 750 /var/log/deluge

The deluge log directory is now configured so that user deluge has full access, group deluge read only and everyone else denied access. The umask specified in the services sets the permission of new log files.

Enable logging in the service files by editing the ExecStart line, appending -l and -L options:

ExecStart=/usr/bin/deluged -d -l /var/log/deluge/daemon.log -L warning

ExecStart=/usr/bin/deluge-web -d -l /var/log/deluge/web.log -L warning

See deluged -h for all available log-levels.

Restart the services:

sudo systemctl daemon-reload
sudo systemctl restart deluged
sudo systemctl restart deluge-web

Conditionally start deluged for mount points

If you have a USB disk drive or network drive that may not be immediately available on boot or disconnected at random then you may want the deluged service to wait for mount point to be ready before starting. If they are unmounted or disconnected then deluged is stopped. When they become available again deluged is started.

Ensure you have added the correct drive details to fstab or equivalent so they are mounted at boot.

List the available drive mounts:

sudo systemctl -t mount

Look for your mount point in the Description column. Mounts are formatted similar to the mount point with -s replacing /s in the path. e.g.: media-xyz.mount

Modify the [Unit] section of the deluged.service script by adding the details below, substituting xyz.mount for the mount you want the service to depend on:

[Unit]
Description=Deluge Bittorrent Client Daemon
# Start after network and specified mounts are available.
After=network-online.target xyz.mount
Requires=xyz.mount
# Stops deluged if mount points disconnect
BindsTo=xyz.mount

For multiple mount points add a space between additional entries. e.g.:

After=network-online.target xyz.mount abc.mount def.mount

Modify the [Install] section to ensure the deluged service is started when the mount point comes back online:

[Install]
WantedBy=multi-user.target xyz.mount

Reference: systemd.unit

https://deluge.readthedocs.io/en/latest/how-to/systemd-service.html