Systemd Service (Linux)

Joular Core ships with a ready-to-use systemd unit file located at systemd/joularcore.service. It lets you run Joular Core as a background daemon that starts on boot and restarts automatically if it crashes.

Default Service Configuration

The included unit file looks like this:

[Unit]
Description=Joular Core service

[Service]
Type=simple
Restart=always
User=root
ExecStart=/usr/bin/joularcore -o -f /tmp/joularcore-service.csv

[Install]
WantedBy=multi-user.target

By default it runs Joular Core as root (required for RAPL access on Linux), writes the latest power reading to /tmp/joularcore-service.csv in overwrite mode (-o), and restarts automatically on failure.

Installation

Copy the unit file to the systemd directory and reload the daemon:

sudo cp systemd/joularcore.service /etc/systemd/system/
sudo systemctl daemon-reload

Enable automatic start on boot and then start the service immediately:

sudo systemctl enable joularcore
sudo systemctl start joularcore

Check that it is running:

sudo systemctl status joularcore

Customisation

You can edit the ExecStart line to pass any Joular Core arguments. For example, to also expose an HTTP API and monitor a specific application:

ExecStart=/usr/bin/joularcore -o -f /tmp/joularcore-service.csv --api-port 8080

Or to write to a ring buffer without any file output:

ExecStart=/usr/bin/joularcore -s -r

After editing the file, reload systemd for the change to take effect:

sudo systemctl daemon-reload
sudo systemctl restart joularcore

Reading the Output File

When using the default -o -f /tmp/joularcore-service.csv configuration, the file always contains exactly one data row — the most recent measurement. Any script or tool can poll this file at its own pace:

cat /tmp/joularcore-service.csv

Example output:

Timestamp,Total Power (W),CPU Power (W),GPU Power (W),CPU Usage (%)
1712345678,18.45,15.20,3.25,24.60

Stopping and Disabling

sudo systemctl stop joularcore
sudo systemctl disable joularcore