We switched over a lot of our operations to open source alternatives around a year ago as well (a writeup is still in the works). We were partially motivated by

We switched over a lot of our operations to open source alternatives around a year ago as well (a writeup is still in the works). We were partially motivated by the money, but more so by the control over our's and our clients' data. One thing to note though is that there are a few things that just make much more sense as a service, or take more effort to actually run yourself than expected. For example, the way they set up Uptime. They moved a lot of stuff over to Digital Ocean, but it sounds like they still have a lot running on Heroku (e.g. all the apps mentioned in the post). But you need your availability monitoring app running on completely separate servers than everything else you run, otherwise it can't tell you when the service behind your apps goes down. In this case, if Heroku or EC2 go down, then the app that is supposed to alert them will also go down, and thus no alerts.