Adding IAM parameters to redshift adapter

[gfeldman]

Describe the feature

I would the arguments to get_cluster_credentials to be added to the dbt profile configuration. In particular DbGroups to allow the temporary user to be added to a group and AutoCreate to allow auto creation of users that do not exist.

Describe alternatives you've considered

Since these are IAM specific configurations the only other alternative is to not use the temporary credentials.

Additional context

This is a feature specifically for redshift users.

Who will this benefit?

This feature will be useful for dbt users who want to use temporary and dynamic credentials with redshift.

[drewbanin]

Thanks for making this issue @gfeldman!

If you're interested in contributing a code change for this feature, the relevant code should be around here:
https://github.com/fishtown-analytics/dbt/blob/40839c79fcf1854942f8db44d1a2648bffe0a2ab/plugins/redshift/dbt/adapters/redshift/connections.py#L39-L57

and here https://github.com/fishtown-analytics/dbt/blob/40839c79fcf1854942f8db44d1a2648bffe0a2ab/plugins/redshift/dbt/adapters/redshift/connections.py#L87-L128

It sounds like we'll just need to state these two configs (DbGroups and AutoCreate) in the set of whitelisted RedshiftCredentials, then pass them through to boto_client.get_cluster_credentials.