Aja Hammerly (@the_thagomizer) shows you how to run rails migrations when you deploy your app with App Engine flexible environment. This video uses CloudSQL 2nd generation.
More information on running Rails on App Engine is available here: https://cloud.google.com/ruby/rails/
Information about setting up Cloud SQL and the Cloud SQL proxy: https://www.youtube.com/watch?v=25XIGXbw_GY
Publisher: Google Cloud
You can watch this video also at the source.