Systemd for Self-Hosters: Managing Services on Linux

What Is Systemd?

Systemd is the init system and service manager on most modern Linux distributions. It starts services at boot, manages their lifecycle, and handles logging.

Essential Commands

Status

systemctl status service-name

Shows if a service is running, its PID, memory usage, and recent logs.

Start/Stop

systemctl start service-name

systemctl stop service-name

Restart

systemctl restart service-name (hard restart)

systemctl reload service-name (reload configuration without restart, if supported)

Enable/Disable

systemctl enable service-name (start at boot)

systemctl disable service-name (don't start at boot)

List Services

systemctl list-units --type=service

Unit Files

Service configuration lives in unit files. View with:

systemctl cat service-name

Custom Unit File

Create /etc/systemd/system/myapp.service:

[Unit]

Description=My Application

After=network.target

[Service]

ExecStart=/usr/bin/myapp

Restart=always

User=deploy

EnvironmentFile=/etc/myapp/env

[Install]

WantedBy=multi-user.target

Then:

systemctl daemon-reload

systemctl enable --now myapp

Journald (Logging)

Systemd includes journald for centralized logging.

View Logs

journalctl -u service-name (all logs for a service)

journalctl -u service-name -f (follow/tail logs)

journalctl -u service-name --since "1 hour ago"

journalctl -u service-name -p err (only errors)

Log Rotation

Configure in /etc/systemd/journald.conf:

SystemMaxUse=500M (limit total log size)

MaxRetentionSec=30day (keep logs for 30 days)

Podman and Systemd

Podman integrates beautifully with systemd. Generate a unit file from a running container:

podman generate systemd --name mycontainer > /etc/systemd/system/mycontainer.service

Now your container starts at boot, restarts on failure, and logs go to journald.

Timers (Cron Alternative)

Systemd timers are a modern alternative to cron:

[Timer]

OnCalendar=daily

Persistent=true

[Install]

WantedBy=timers.target

Advantages over cron: