I've been using systemctl to manage multiple python scripts on raspberry pi 3b running jessie for a while. I recently got a rpi 3b+ and installed the lates Stretch on it. Set up the exact same way as the older one but can't get the services working properly. Below is the service and the python script i am testing just now.
[Unit] Description=Keep Alive Service After=multi-user.target [Service] Type=idle ExecStart=/usr/bin/python /home/pi/Desktop/keep_alive.py > /home/pi/Desktop/keep_alive.log 2>&1 Restart=always [Install] WantedBy=multi-user.target
import time import os while 1: command = 'sshpass -p "server_pass" ssh -N -o ExitOnForwardFailure=yes -R port:localhost:22 server_username@server_ip_address' os.system(command) time.sleep(60)
This should create a reverse ssh tunnel to a server to allow me for remote login to the pi.
Now if i enable and start the service, then check its status i get the following:
● keep_alive_service.service - Keep Alive Service Loaded: loaded (/lib/systemd/system/keep_alive_service.service; enabled; vend Active: active (running) since Fri 2018-06-15 09:44:08 BST; 12min ago Main PID: 24289 (python) CGroup: /system.slice/keep_alive_service.service └─24289 /usr/bin/python /home/pi/Desktop/keep_alive.py > /home/pi/Desktop/keep_alive.log 2>&1 Jun 15 09:44:08 M-HAS systemd: Started Keep Alive Service.
And also checking with ps -aef | grep python i see the script is running:
root 24289 1 0 09:44 ? 00:00:00 /usr/bin/python /home/pi/Desktop/keep_alive.py > /home/pi/Desktop/keep_alive.log 2>&1
However am sure the tunnel is not created. If i try to log in from the server i get connection refused. If i manually run the script it works fine.
So i tried a couple more things to udnerstand how the python script is run by systemctl (since it shows as running). First of all i tried:
- stop the service.
- disconnect the pi form the internet.
- restart the service.
Checking the status and logs i can see (as expected) an error "Network is unreachable" when the ssh command is executed, and then again every 60 seconds after since the loop keeps going.
Now, i reconnected the pi to the internet added a print line just after the ssh command within the script as follows:
import time import os while 1: command = 'sshpass -p "server_pass" ssh -N -o ExitOnForwardFailure=yes -R port:localhost:22 server_username@server_ip_address' os.system(command) print 'got here' time.sleep(60)
So again, if i run the script manually, all works well and that print never gets printed out since python doesn't get past the os.system().
However if i run the script with systemctl it seems that the os.system() somehow fails, and 'got here' is printed. The thing is, there is no actual errors shown, neither in the log or when checking the status of the service. This is way i tested without internet connection earlier to see what would happend, and did get "Network is unreachable". This just confused me even more.
Also this whole set up works fine on a rpi 3b running jessie.
Is there some difference between jessie / stretch and or rpi 3b and rpi 3b+ when using systemctl? I cant figure out what is wrong.