How to restart kivy app after updating (exit old version & execute new version)

Question

How can I have a kivy app restart after downloading a new version of itself?

I'm developing a python GUI app that uses the kivy framework, I just added an auto-update feature to my app that securely downloads, verifies, and extracts a newer version of itself. After these upgrade steps are complete, I present the user with a modal dialog asking them to click a button to restart the app to the newer version.

How can I get that button to actually close the window and execute the new kivy app?

Answer 1

In python, you can use os.execv() to exit the current process and replace it with another execution.

The following commands demonstrate how to do this with kivy in Debian 10:

sudo apt-get -y install python3 python3-pip python3-virtualenv python3-setuptools
sudo dpkg -l | grep python

python3 -m virtualenv --python=python3.7 /tmp/virtualenv/kivy_test
/tmp/virtualenv/kivy_test/bin/python3 -m pip install --upgrade pip kivy
/tmp/virtualenv/kivy_test/bin/python3 -m pip list
source /tmp/virtualenv/kivy_test/bin/activate

tmpDir=`mktemp -d`
pushd "${tmpDir}"

cat << EOF > helloWorldOne.py
#!/usr/bin/env python3
import kivy, os
from kivy.app import App
from kivy.uix.label import Label
from kivy.clock import Clock

class MyApp(App):
    def build(self):
        Clock.schedule_once( self.restart, 1 )
        return Label(text='Hello World One!')

    def restart(self, dt):
        os.execv( 'helloWorldTwo.py', ['helloWorldTwo.py'] )

if __name__ == '__main__':
    MyApp().run()
EOF

cat << EOF > helloWorldTwo.py
#!/usr/bin/env python3
import kivy, os
from kivy.app import App
from kivy.uix.label import Label
from kivy.clock import Clock

class MyApp(App):
    def build(self):
        return Label(text='Hello World Two!')

if __name__ == '__main__':
    MyApp().run()
EOF

chmod +x helloWorld*.py
./helloWorldOne.py

popd

When ./helloWorldOne.py is executed above, a window (the "old version") appears. After a 1 second delay, the restart() function is executed (which instead could be bound to a button)--which calls os.execv().

The helloWorldOne.py app window is closed and replaced with the helloWorldTwo.py app window.