If your blue and green environments are in the same AWS region, and you don’t have to account for schema changes, you can have both environments tap into the same data sources, significantly simplifying your deployment process.
If you do need to account for schema changes, a simpler way to handle that is to decouple schema changes from code changes. By using decoupling, you can choose one of two approaches:
Database updates are backward compatible
Code changes are backward compatible with the old schema