sqlserver: add IAM authentication support

[danielnelson]

Current Behavior

The sqlserver connectors have support for username/password authentication.

Desired Behavior

Add IAM support to the source-sqlserver and materialize-sqlserver connectors. Ideally, this would be across all supported cloud providers, similar to the the postgres connector.

• SQL Server
  • source-sqlserver
    • Azure
    • GCP
    • AWS IAM
  • materialize-sqlserver
    • Azure
    • GCP
    • AWS IAM

[danielnelson]

I don't think it will be possible to support IAM authentication in GCP. Cloud SQL does not support IAM authentication to SQL Server:

Cloud SQL for SQL Server supports IAM authentication for instance and backup operations only. IAM authentication isn't supported for database operations. Use the following authentication options for database operations and queries:¹

I looked into using Cloud SQL Auth Proxy in a similar setup to RDS Proxy, but it doesn't appear to allow IAM to the proxy and then mapping to database credentials in a similar way to RDS Proxy, only end-to-end IAM auth with Postgres and MySQL.

Footnotes

1. https://docs.cloud.google.com/sql/docs/sqlserver/iam-authentication ↩

[dyaffe]

Cool, makes sense -- is it possible to not have us show that tab?

[danielnelson]

Yes, that's no problem.