Engineering Posted 6/16/15 Eric Holmes Full-stack & Infrastructure Today, Remind is open sourcing our self-hosted PaaS called Empire . Empire provides a 12 factor-compatible , Docker-based container cluster built on top of Amazon’s robust EC2 Container Service (ECS), complete with a full-featured command line interface. Why build Empire when Heroku already exists (and works well for so many)? Well, here’s the story of why we decided to move off of Heroku, the challenges we encountered along the way, and how we built Empire as a solution for making the migration to Amazon ECS as painless as possible. Back in 2011, Remind started as a single monolithic Rails app, hosted on Heroku. Things were simpler then: one app with a couple of dynos was more than enough to handle our trickle of traffic. We chose Heroku because it allowed us to focus on building product rat...