Systemctl blocking when starting my deamon

Question

I have written a small daemon in Python with:

#!/usr/bin/python3

import time
import click
import daemonocle

from daemonocle.cli import DaemonCLI

@click.command(cls=DaemonCLI, daemon_params={'pidfile': '/var/run/daemon.pid'})
def main():
    while True:
        time.sleep(3)

if __name__ == '__main__':
    main()

It works great as is. If I do the following I get a good exit status 0

$ sudo ./daemon start 
Starting daemon ... OK    

$ echo $?
0

Then I wrote a systemd service file:

[Unit]
SourcePath=/home/pi/daemon/daemon
Description=My First Daemon
Before=multi-user.target
After=mosquitto.target

[Service]
Type=forking
PIDFile=/var/run/daemon.pid
Restart=no
ExecStart=/home/pi/daemon/daemon start
ExecStop=/home/pi/daemon/daemon stop
ExecReload=/home/pi/daemon/daemon reload

And if I try to run my daemon with systemctl the command remains blocking:

$ sudo systemctl start daemon
^C
$ sudo systemctl status daemon
? daemon.service - XEMWAY Demo Service
   Loaded: loaded (/home/pi/daemon/daemon; static; vendor preset: enabled)
   Active: activating (start) since Wed 2019-02-13 13:47:40 GMT; 12s ago
  Process: 13044 ExecStop=/home/pi/daemon/daemon stop (code=exited, status=0/SUCCESS)
 Main PID: 12304 (code=exited, status=143); Control PID: 13079 (daemon)
   CGroup: /system.slice/daemon.service
           +-13079 /usr/bin/python3 /home/pi/daemon/daemon start
           +-13081 /usr/bin/python3 /home/pi/daemon/daemon start

After one minute systemd says:

Feb 13 13:49:10 raspberrypi systemd[1]: daemon.service: Unit entered failed state. Feb 13 13:49:10 raspberrypi systemd[1]: daemon.service: Failed with result 'timeout'.

What's wrong with this?

Answer 1

The issue is that your service creates daemon by it's own and systemd doesn't know about it. It's just a simple program that runs and exit after little amount of time for systemd. Instead of forking you want to use simple:

Type=simple

Systemd wil still track your process as a daemon, since it knows its pid:

systemctl status test2.service

* test2.service - My First Daemon
   Loaded: loaded (/tmp/a.py; static; vendor preset: disabled)
   Active: active (running) since Wed 2019-02-13 16:06:27 EET; 5s ago
 Main PID: 18104 (python)
    Tasks: 2 (limit: 4915)
   Memory: 10.1M
   CGroup: /system.slice/test2.service
           |-18104 /usr/bin/python /tmp/a.py start
           `-18115 /usr/bin/python /tmp/a.py start