Here's another example of AWS interactions with OSS: instead of contributing a perfectly good and non-AWS dependant feature to an upstream project (PGBouncer, for a strictly PostgreSQL-level useful feature) they decided to rather stretch it and publish their changes as a _patch_ to the upstream project instead, with a different, restrictive license that only allows its usage on AWS services, together with examples on how to use it on RDS/Redshift:
https://github.com/awslabs/pgbouncer-rr-patch/
https://github.com/awslabs/pgbouncer-rr-patch/issues/3