Is it possible to configure a Postgres 9.1 database running in EC2 to be the source for a Heroku Postgres follower database? In other words:
$ heroku config:set MY_DATABASE_URL=postgres://my_user:my_pass@my_ec2_server:5432/my_db
$ heroku addons:add heroku-postgresql:ronin --follow MY_DATABASE_URL
What settings would be required on the source database to allow for this?
No, sorry, not possible. We are only able to fork or follow databases that we provision.