启动后尝试使用 systemd 运行服务

Question

I have listed below the steps as I entered them. I cannot get the Pi (Raspbian GNU/Linux Buster (10)) to launch alarm.service after startup. When I log into the Pi and launch alarm.service manually from the GUI it works, as does the script it runs -- (The script is written to loop) Only problem is I can't get alarm.service to launch automatically without the GUI. Be great to have it launch last after all other services are up and running.

1. sudo nano /home/pi/alarm_service.py - (fyi: this script runs nicely when i launch it manually from command prompt after pi has booted and i am logged in)
2. sudo nano /etc/systemd/system/alarm.service

[Unit]
Description=Alarm Service
After=multi-user.target
Conflicts=getty@tty1.service
[Service]
Type=simple
ExecStart=/home/pi/alarm_service.py
StandardInput=tty-force
[Install]
WantedBy=multi-user.target

3. sudo chmod 644 /etc/systemd/system/alarm.service
4. sudo systemctl daemon-reload
5. sudo systemctl enable alarm.service
6. sudo systemctl start alarm.service

Error log: alarm.service - Alarm service Loaded: loaded (/etc/systemd/system/alarm.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Fri 2021-05-14 18:57:24 AEST; 1min 18s ago Process: 501 ExecStart=/home/pi/alarm_service.py (code=exited, status=1/FAILURE) Main PID: 501 (code=exited, status=1/FAILURE)

May 14 18:57:24 raspberrypi alarm_service.py[501]: File "/usr/local/lib/python2.7/dist-packages/paho/mqtt/client.py", line 10 May 14 18:57:24 raspberrypi alarm_service.py[501]: sock = self._create_socket_connection() May 14 18:57:24 raspberrypi alarm_service.py[501]: File "/usr/local/lib/python2.7/dist-packages/paho/mqtt/client.py", line 35 May 14 18:57:24 raspberrypi alarm_service.py[501]: return socket.create_connection(addr, source_address=source, timeout=sel May 14 18:57:24 raspberrypi alarm_service.py[501]: File "/usr/lib/python2.7/socket.py", line 575, in create_connection May 14 18:57:24 raspberrypi alarm_service.py[501]: raise err May 14 18:57:24 raspberrypi alarm_service.py[501]: socket.error: [Errno 101] Network is unreachable May 14 18:57:24 raspberrypi systemd[1]: alarm.service: Main process exited, code=exited, status=1/FAILURE May 14 18:57:24 raspberrypi systemd[1]: alarm.service: Failed with result 'exit-code'. May 14 18:57:24 raspberrypi systemd[1]: Failed to start Alar m service.

Answer 1

The principle I follow is to make the environment that systemd creates for the script to run as similar to what I use to develop it as possible.

For the sake of testing I just ran shutdown -r now on a VM where I do this exact thing. On boot, voila.

$ systemctl status mypython
● mypython.service
   Loaded: ...etc.

The file I have set is

less /etc/systemd/system/multi-user.target.wants/mypython.service

Content

[Unit]
        Description=mypython
        
        [Service]
        WorkingDirectory=/home/me
        ExecStart=/usr/bin/python3 /home/me/mypython.py ./config.yaml
        Restart=always
        RestartSec=5
        User=me
        Group=me

        [Install]
        WantedBy=multi-user.target