Make migrations path relative to ini

[dstandish]

This makes it so that we can alembic commands from the root repo dir.

E.g.

alembic -c airflow/alembic.ini revision --autogenerate -m "Do something"

Sometimes when running from airflow subfolder we get errors.

[ephraimbuddy]

I had instructed contributors to copy the airflow’s alembic.ini here https://github.com/apache/airflow/blob/main/contributing-docs/13_metadata_database_updates.rst#create-alembic-migration-scripts. Maybe we should also update there

[dstandish]

I had instructed contributors to copy the airflow’s alembic.ini here https://github.com/apache/airflow/blob/main/contributing-docs/13_metadata_database_updates.rst#create-alembic-migration-scripts. Maybe we should also update there

I don't really understand the implications re what that section is about and how this would impact that. Can you possibly make a suggestion re what I should change?

[ephraimbuddy]

https://github.com/apache/airflow/blob/main/contributing-docs/13_metadata_database_updates.rst#create-alembic-migration-scripts

This line in the doc:
Replace the content of your application's alembic.ini file with Airflow's alembic.ini copy..

I'm not sure it will work if copied over. WDYT?

[ephraimbuddy]

Tested and it works

[ephraimbuddy]

We can also update the one at airflow/providers/fab/alembic.ini

[dstandish]

Tested and it works

Thanks a bunch Ephraim 🙏