Automating Python Execution on a Raspberry Pi with a virtual environment

26 Aug 2024

In this guide, you will learn how to automate the execution of a Python script on your Raspberry Pi using a systemd service. This can be particularly useful for running scripts automatically at startup without any manual intervention.

Step 1: Create a systemd Service File

First, create a new service file in the /etc/systemd/system/ directory. You can name this file anything you like, but for this guide, we’ll use mygoodcode.service.

sudo nano /etc/systemd/system/mygoodcode.service

Step 2: Add the Following Content to the Service File

Replace the paths and script names as needed for your setup. This service will activate a Python virtual environment and run a Python script.

[Unit]
Description=mygoodcode Python Script Service
After=network.target

[Service]
User=iot
WorkingDirectory=/home/iot/mygoodcode
ExecStart=/bin/bash -c 'source /home/iot/mygoodcode/bin/activate; /usr/bin/python3 /home/iot/mygoodcode/app.py'
Restart=always
Environment=PYTHONUNBUFFERED=1

[Install]
WantedBy=multi-user.target

To exit nano after pasting use ctrl+x choose yes (Y) when asked to save modified buffer. Hit the Enter key to confirm the file name and you should be back in the terminal.

Explanation:

User: This specifies the user under which the script will run (replace iot with your actual username if different).
WorkingDirectory: The directory where your script and virtual environment are located.
ExecStart: This is the command to start your script. It first activates the virtual environment and then runs the Python script.
Restart: Ensures that the service is always restarted if it fails.
Environment: The PYTHONUNBUFFERED=1 setting makes sure that the Python output is flushed immediately, which can be useful for logging.

Step 3: Reload systemd Configuration

After creating the service file, reload the systemd configuration to apply the changes:

sudo systemctl daemon-reload

Step 4: Enable the Service to Start on Boot

Enable the service to automatically start at boot:

sudo systemctl enable mygoodcode.service

Step 5: Start the Service Manually to Test It

Start the service manually to ensure everything is working correctly:

sudo systemctl start mygoodcode.service

You can check the status of the service to verify that it’s running:

sudo systemctl status mygoodcode.service

Step 6: Troubleshooting

If the service fails to start, check the logs for more details:

journalctl -u mygoodcode.service -b

This will show you the full log of the service, which may provide more insight into any issues.

Conclusion

By following this guide, you’ve successfully automated the execution of your Python script using systemd. Your script will now run automatically on boot and restart if it ever crashes.