Fix/datastore vars optional

[sophie-daintta]

Context

Update datastore variables to optional to allow for automatic boto3 credentials:

• All datastore variable made optional apart from bucket name.

Guidance to review

Declared but empty environment variables cause empty string inputs which errors on datastore port input, should this be accounted for explicitly?

Checklist:

• My code follows the style guidelines of this project
• New and existing unit tests pass locally with my changes

[wpfl-dbt]

I think we should use a different approach: keep those attributes as mandatory, but configure the default AWS environment variable names as custom fallback environment variable names. Pydantic documentation.

You'd do something like:

class MatchboxDatastoreSettings(BaseSettings):
    ...
    access_key_id: SecretStr = Field(..., env=["MB__DATASTORE__ACCESS_KEY_ID", "AWS_ACCESS_KEY_ID"])

You might have some trouble with how it plays with the MB__ suffix structure is the only thing.

I also don't know about how these creds are set in ECS. Would this work?

[wpfl-dbt]

Discussed, let's go for it.