Here are the steps I followed to get over this.
My requirement was to run the bookshelf python tutorial application as detailed in
https://cloud.google.com/python/getting-started/tutorial-app
and I was getting stuck at the cloud_sql_proxy error.
https://cloud.google.com/python/getting-started/using-cloud-sql
Following are the steps I did
1) I created a service account with Cloud SQL Client role as detailed in https://cloud.google.com/sql/docs/mysql/sql-proxy#create-service-account
2) I downloaded the json credential file
3) Used the command
./cloud_sql_proxy -instances=[CONNECTIONINSTANCE]=tcp:3306 -credential_file=./mycredentials.json
4) Then opened up a mysql -u root -p --host 127.0.0.1
Oh btw, I also had a problem with my date time on my virtualbox.
issue the command timedatectl to see if your local time on the virtualbox (ubuntu) is proper. If you have the habit of using hibernating the VM using "save" option instead of a shutdown, most probably the time is out of sync. you better do a restart of the VM and this problem will go away
All the best with your Google Cloud App development!
Thanks to @Fady who helped me out with this issue