RDS: Determine parameter group family from engine version

[MisterMX]

What problem are you facing?

Currently, rds.aws.crossplane.io/v1alpha1/DBParameterGroup mirrors the behaviour of the AWS API by requiring dbParameterGroupFamily as input from the user.

However, determining the actual name from the engine and engineVersion parameters can be very cumbersome in a composition. It is made even harder by the inconsistency of the AWS API:

• for SQL Server 15.00.4198.2.v1 the group family is sqlserver-se-15.0 missing the additional 0
• for Oracle 12.1.0.2.v1 its oracle-ee-12.1, but for 19.0.0.0.ru-2019-07.rur-2019-07.r1 its just oracle-ee-19 missing the minor version.

The list goes on.

How could Crossplane help solve your problem?

Instead of letting the user / composition writer deal with this problem, the provider should offer a shortcut by determining the group family by himself:

1. Make spec.forProvider.dbParameterGroupFamily optional
2. Add a new field dbParameterGroupFamilyFromEngine

spec:
  forProvider:
    dbParameterGroupFamilyFromEngine:
      engine: sqlserver-se
      engineVersion: "15.00.4198.2.v1" # optional

3. If dbParameterGroupFamily is not set the provider should take dbParameterGroupFamilyFromEngine and get the family name using

aws rds describe-engine-versions --engine ... --engine-version ...

5. If dbParameterGroupFamilyFromEngine.engineVersion is not set, the provider should use the family of the default version by calling

aws rds describe-engine-versions --engine ... --default-only