I understand this might be an easy solution, but I am very new to this so any help would be appreciated.
I have been running through the hello world application for node.js with managed vms on google compute engine, and I have just done this stage
gcloud preview app deploy app.yaml --promote
Which has allowed me to put up the app, and it works.
BUT HOW do I now update that code? If I run that command again it starts up new instances and essentially treats it like a new upload.