Run Alembic migrations on Google App Engine

Question

I have a Flask app that uses SQLAlchemy (Flask-SQLAlchemy) and Alembic (Flask-Migrate). The app runs on Google App Engine. I want to use Google Cloud SQL.

On my machine, I run python manage.py db upgrade to run my migrations against my local database. Since GAE does not allow arbitrary shell commands to be run, how do I run the migrations on it?

Answer 1

• Whitelist your local machine's IP: https://console.cloud.google.com/sql/instances/INSTANCENAME/access-control/authorization?project=PROJECTNAME
• Create an user: https://console.cloud.google.com/sql/instances/INSTANCENAME/access-control/users?project=PROJECTNAME
• Assign an external IP address to the instance: https://console.cloud.google.com/sql/instances/INSTANCENAME/access-control/ip?project=PROJECTNAME
• Use the following SQLAlchemy connection URI: SQLALCHEMY_DATABASE_URI = 'mysql://user:pw@ip:3306/DBNAME'
• Remember to release the IP later as you are charged for every hour it's not used

Answer 2

It's all just code you can run, so you can create an admin endpoint with which to effect an upgrade:

@app.route('/admin/dbupgrade')
def dbupgrade():
    from flask_migrate import upgrade, Migrate
    migrate = Migrate(app, db)
    upgrade(directory=migrate.directory)
    return 'migrated'

(Dropwizard, for instance, caters nicely for such admin things via tasks)