The applications update is manual. You will need to SSH into the VM and run following commands in sequence. Once updated, you will have to clear browser cache so that new contents can be shown (Follow this link to reload application in the browser - https://fabricdigital.co.nz/blog/how-to-hard-refresh-your-browser-and-clear-cache)
gcloud auth --quiet configure-docker
The following steps are needed to be done only once (if missing)
... ... ChrootDirectory %h/gcs ... ...