Add More Granular Check to Postgres User During setup_db

[mradamcox]

User Story
Currently, in our setup_db command, there is a check to determine whether the user is a superuser: https://github.com/archesproject/arches/blob/master/arches/management/commands/setup_db.py#L152

cursor.execute("SELECT current_setting('is_superuser')")

If the user is a superuser, then the DROP/CREATE db commands are run to make a completely fresh installation of the Arches database. This must happen the very first time that the database is setup. If the user is not a superuser, then a "reset" of the database is undertaken, where all the data is flushed, but no CREATE commands are run. This can be done over and over by a non-superuser, but only if the database has been created already.

I have found that on AWS RDS (and perhaps other hosted Postgres solutions) the "superuser" you are provided with is not actually a superuser in the proper sense, but it has a more specific set of privileges (which do include the ability to create a database).

This means that in the case of RDS, the user is not properly flagged as a "superuser" with our current code, which triggers the database reset instead of the database creation, which, in turn, fails if the database hasn't yet been created.

Proposal

I have tested and confirmed that in the case of RDS, replacing the superuser check above with this check:

cursor.execute("SELECT rolcreatedb FROM pg_roles WHERE rolname = '{}'".format(username))

does properly determine whether the user has the ability to create databases, so it can be used to trigger the database creation.

Acceptance Criteria

• Unit Tests passed
• Documentation

Definition of Done
setup_db must continue to work, but should use a more specific check for whether the user has permission to create databases on the server.

[mradamcox]

This is now addressed, in stable/4.4.x (before the 4.4.2 release) and in master.

[mradamcox]

@whatisgalen figured out this is not a sufficient fix, as the "Superuser" attribute does allow the creation of databases, but it doesn't actually bring along the "Create DB" attribute. A little more work needs to be done on this, presumably just additionally checking for rolsuper.

[mradamcox]

The fix for this is now in stable/4.4.x and master, so I'm re-closing the ticket.