sensorpajen/systemd/README.md

Systemd Service Installation

Installing Sensorpajen as a User Service

This allows sensorpajen to run automatically on boot as your user (no sudo required for management).

Installation Steps

1. Install the Service File

cd ~/sensorpajen

# Create user systemd directory if it doesn't exist
mkdir -p ~/.config/systemd/user/

# Copy service file
cp systemd/sensorpajen.service ~/.config/systemd/user/

# Reload systemd to recognize the new service
systemctl --user daemon-reload

2. Enable Lingering (Run Without Login)

This allows your user services to run even when you're not logged in:

# Enable lingering for your user
sudo loginctl enable-linger $USER

# Verify it's enabled
loginctl show-user $USER | grep Linger
# Should show: Linger=yes

3. Start and Enable the Service

# Start the service now
systemctl --user start sensorpajen

# Enable it to start on boot
systemctl --user enable sensorpajen

# Check status
systemctl --user status sensorpajen

Service Management Commands

# Start the service
systemctl --user start sensorpajen

# Stop the service
systemctl --user stop sensorpajen

# Restart the service
systemctl --user restart sensorpajen

# Check status
systemctl --user status sensorpajen

# View logs (all)
journalctl --user -u sensorpajen

# View logs (follow/tail)
journalctl --user -u sensorpajen -f

# View logs (last 100 lines)
journalctl --user -u sensorpajen -n 100

# View logs (since specific time)
journalctl --user -u sensorpajen --since "1 hour ago"
journalctl --user -u sensorpajen --since "2025-12-27 10:00"

# Enable service (start on boot)
systemctl --user enable sensorpajen

# Disable service (don't start on boot)
systemctl --user disable sensorpajen

Viewing Logs

The service logs to systemd journal. View them with:

# Live view (like tail -f)
journalctl --user -u sensorpajen -f

# With timestamps
journalctl --user -u sensorpajen -f -o short-iso

# Just today's logs
journalctl --user -u sensorpajen --since today

Updating the Service

After making changes to the code:

# Pull latest changes
cd ~/sensorpajen
git pull origin master

# Restart the service to apply changes
systemctl --user restart sensorpajen

# Check it started correctly
systemctl --user status sensorpajen

After editing sensorpajen.service:

# Copy updated service file
cp systemd/sensorpajen.service ~/.config/systemd/user/

# Reload systemd configuration
systemctl --user daemon-reload

# Restart the service
systemctl --user restart sensorpajen

After editing configuration files:

# Edit config
nano ~/sensorpajen/config/sensorpajen.env
# or
nano ~/sensorpajen/config/sensors.json

# Restart service to reload config
systemctl --user restart sensorpajen

Troubleshooting

Permission Denied Errors

If you see PermissionError: [Errno 1] Operation not permitted in the logs:

# Verify Bluetooth capabilities are set on Python binary
getcap ~/.local/share/virtualenvs/*/bin/python3.*

# If not set, apply capabilities (adjust path to your venv):
sudo setcap 'cap_net_raw,cap_net_admin+eip' $(readlink -f ~/sensorpajen/.venv/bin/python3)

# Verify it was set:
getcap $(readlink -f ~/sensorpajen/.venv/bin/python3)
# Should show: cap_net_admin,cap_net_raw+eip

# Restart the service
systemctl --user restart sensorpajen

Important: Capabilities must be set on the actual Python binary, not symlinks. Use readlink -f to resolve the real path.

Service Won't Start

# Check detailed status
systemctl --user status sensorpajen

# Check logs for errors
journalctl --user -u sensorpajen -n 50

# Test the command manually
cd ~/sensorpajen
source .venv/bin/activate
export $(cat config/sensorpajen.env | grep -v '^#' | xargs)
python -m sensorpajen.main

Bluetooth Permission Errors

Make sure capabilities are set on the Python binary:

getcap $(readlink -f ~/.venv/bin/python3)
# Should show: cap_net_raw,cap_net_admin+eip

# If not set:
sudo setcap 'cap_net_raw,cap_net_admin+eip' $(readlink -f ~/sensorpajen/.venv/bin/python3)

Service Doesn't Start on Boot

# Check if service is enabled
systemctl --user is-enabled sensorpajen
# Should show: enabled

# Check if lingering is enabled
loginctl show-user $USER | grep Linger
# Should show: Linger=yes

# If not enabled:
systemctl --user enable sensorpajen
sudo loginctl enable-linger $USER

Environment Variables Not Loading

# Verify environment file exists and is readable
cat ~/sensorpajen/config/sensorpajen.env

# Check file permissions
ls -la ~/sensorpajen/config/sensorpajen.env

# Test loading manually
export $(cat ~/sensorpajen/config/sensorpajen.env | grep -v '^#' | xargs)
env | grep MQTT

Verifying Everything Works

After installation:

# 1. Check service is running
systemctl --user status sensorpajen

# 2. Check logs show sensor data
journalctl --user -u sensorpajen -f

# 3. Check MQTT messages are being published
mosquitto_sub -h 192.168.0.114 -u hasse -P casablanca -t "MiTemperature2/#" -v

# 4. Reboot and verify it starts automatically
sudo reboot
# After reboot:
systemctl --user status sensorpajen

Uninstalling the Service

If you need to remove the service:

# Stop and disable
systemctl --user stop sensorpajen
systemctl --user disable sensorpajen

# Remove service file
rm ~/.config/systemd/user/sensorpajen.service

# Reload systemd
systemctl --user daemon-reload

# Optionally disable lingering
sudo loginctl disable-linger $USER

Notes

• User Service: Runs as your user, not root - more secure and easier to manage
• Lingering: Required for services to run when not logged in
• Logs: All output goes to systemd journal (journalctl)
• Auto-restart: Service restarts automatically on crashes
• Environment: Config loaded from config/sensorpajen.env
• Working Directory: Service runs from ~/sensorpajen

Next Steps

Once the service is working:

1. Monitor for a few days to ensure stability
2. Check logs occasionally: journalctl --user -u sensorpajen --since yesterday
3. Service will survive reboots and automatically restart on failures