Python • GPIO trouble when running as a service:

Code:

set -eSCRIPT_PATH="/usr/local/bin/power_button.py"SERVICE_PATH="/etc/systemd/system/power-button.service"echo "Installing Python script..."install -m 0755 power_button.py "$SCRIPT_PATH"echo "Creating systemd service..."cat > "$SERVICE_PATH" <<'UNIT'[Unit]Description=CM4 Power Button & Status LEDWants=dev-gpiomem.device dev-gpiochip0.deviceAfter=dev-gpiomem.device dev-gpiochip0.device multi-user.targetConditionPathExists=/dev/gpiochip0[Service]Type=simpleWorkingDirectory=/home/pilotEnvironment=PYTHONUNBUFFERED=1Environment=GPIOZERO_PIN_FACTORY=lgpioExecStart=/usr/bin/python3 -u /usr/local/bin/power_button.pyRestart=on-failureRestartSec=2User=pilotSupplementaryGroups=gpioPrivateDevices=noStandardOutput=journalStandardError=journal[Install]WantedBy=multi-user.targetUNITecho "Reloading systemd and enabling service..."systemctl daemon-reloadsystemctl enable --now power-button.serviceecho "Service installed and started."systemctl status power-button.service --no-pager

Code:

from gpiozero import LED, Buttonimport timeimport threadingimport subprocessimport sys# --- begin: service-sanity ---import os, timeprint(f"[boot] uid={os.getuid()} gid={os.getgid()} groups={os.getgroups()}", flush=True)for path in ("/dev/gpiochip0", "/dev/gpiomem"):    for _ in range(50):        if os.path.exists(path):            break        time.sleep(0.1)# --- end: service-sanity ---LED_PIN = 21BUTTON_PIN = 20led = LED(LED_PIN)button = Button(BUTTON_PIN, pull_up=True, bounce_time=0.05, hold_time=3.0)shutdown_triggered = threading.Event()def forever_pulse_led():    print("[worker] awaiting btn...", flush=True)    while not shutdown_triggered.is_set():        led.toggle()        time.sleep(0.1 if button.is_pressed else 0.5)def on_button_held():    # handling continuous long press    print("[event] Button longpress -> SHUTDOWN requested", flush=True)    shutdown_triggered.set()    led.on()    time.sleep(0.5)    try:        subprocess.run(["sudo", "poweroff"], check=False)    except Exception as e:        print(f"[error] poweroff failed: {e}", file=sys.stderr, flush=True)button.when_held = on_button_heldtry:    print("[main] Starting...", flush=True)    led.off()    pulse_thread = threading.Thread(target=forever_pulse_led)  # non-daemon    pulse_thread.start()    # Keep main alive until shutdown    while not shutdown_triggered.is_set():        time.sleep(0.5)except KeyboardInterrupt:    print("[main] KeyboardInterrupt", flush=True)