You need to provide a migration account with a copy of a production RDS database snapshot. The RDS instance is encrypted with a KMS key (alias production-rds-key). What is the approach with the LEAST administrative overhead to share the snapshot with the migration account?

The correct approach involves creating a snapshot of the RDS instance in the production account, then updating the KMS key policy for production-rds-key to grant the migration account's root principal access. Finally, share the snapshot with the migration account. This method is efficient because it directly leverages existing encryption and sharing mechanisms. The migration account can then copy the shared snapshot, re-encrypting it with their own KMS key if desired. Creating an RDS read replica in the migration account is not a direct snapshot sharing mechanism and involves more setup. Taking a snapshot, sharing it, and then creating a new KMS key with the same alias in the migration account doesn't directly facilitate the re-encryption process required for cross-account sharing of an encrypted snapshot. Exporting the database to S3 and then importing it is a data migration strategy, not a snapshot sharing strategy, and involves significantly more administrative overhead and potential downtime.