RDS to S3 using pg_dump directly (without intermediary)
The AWS CLI added support for uploads from stdin, so you now have the option of doing something like this:
pg_dump ...dbargs... | aws s3 cp - s3://my-bucket/backup-$(date "+%Y-%m-%d-%H-%M-%S")It's not ideal, as you are streaming to your local machine and then into s3 - but it's at least a single command.
You should be able to access it as long as your db security group allows external access to port 5432 (default for postgres). Then you can just run:
pg_dump -h <database_host> -U <username> <database>Keep in mind that your connection will not be encrypted.
AFAIK, there is no interface in AWS between RDS and S3, so you would have to use an intermediary to transfer the data to S3.