With Heroku, they give you their user id so you can tell EC2 to only allow connections from the heroku servers. It limits it a bit more than other PaaS, but it

With Heroku, they give you their user id so you can tell EC2 to only allow connections from the heroku servers. It limits it a bit more than other PaaS, but it is still not pretty secure. See https://devcenter.heroku.com/articles/external-services https://devcenter.heroku.com/articles/external-services for details...