Currently, the process is very manual though.
The manual process:
- git push will automatically create a new image on GCR
- Go to Compute Engine, and create a new machine 
- specify the image as the one we just pushed
- put the needed env variables (check the project settings.py for that)

Git push does everything automatically.
1. Google build run the CI automatically.
2. If all is well, an image is built
3. Google Run is redeployed using the new image