How can I make a script autostart in a virtual environment in Raspbian?

Question

The script is a Python script and works in a virtual environment. Made a shell script "launch.sh" that looks like this:

cd /home/pi/test_iot
. bin/activate
python3 rtl433_to_mqtt.py

If I run this from the console it works but not from cron. Running "sudo crontab -e" and then added this line: @reboot sh /home/pi/launch.sh >/home/pi/logs/cronlog 2>&1

I get this error log:

Traceback (most recent call last):
  File "/home/pi/test_iot/rtl433_to_mqtt.py", line 120, in <module>
  File "/home/pi/test_iot/lib/python3.11/site-packages/paho/mqtt/client.py", line 914, in connect
    return self.reconnect()
           ^^^^^^^^^^^^^^^^
  File "/home/pi/test_iot/lib/python3.11/site-packages/paho/mqtt/client.py", line 1044, in reconnect
    sock = self._create_socket_connection()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/test_iot/lib/python3.11/site-packages/paho/mqtt/client.py", line 3685, in _create_socket_connection
    return socket.create_connection(addr, timeout=self._connect_timeout, source_address=source)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/socket.py", line 851, in create_connection
    raise exceptions[0]
  File "/usr/lib/python3.11/socket.py", line 836, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

I have no clue what's happening here so I hope someone here can see what's wrong.

Answer 1

It's hard to tell by the information provided. My guess is that the cron-job is firing before any network facilities are available. Instead of using @reboot from cron, try a systemd service running after networking is available.

Answer 2

Both advices I got here worked perfect but I finally decided to use the service-version as I suspect it is more safe than waiting 60 seconds.

The service defined as:

[Unit]
Description=Temperature monitoring through RTL-SDR reciever
After=network-online.target

[Service]
Type=idle
ExecStart=/home/pi/launch.sh
Restart=always

[Install]
WantedBy=multi-user.target

The running script:

enter code here
#!bin/bash
cd /home/pi/test_iot
. bin/activate
#sleep 60# Not needed as we run it as a service that delays start until network online. When run as a cron-job it is needed
python3 rtl433_to_mqtt.py