We have been deploying/running production applications for about two years now and the first problem that comes to mind while deploying OTP releases is Build-time vs Run-time environment configuration. While running a Mix project there isn’t much of a difference between build-time and run-time as you are running the app in the same environment in which you’re compiling (building) it. However, that might not be the case when using releases. At Annkissam, we have come up with a few solutions to that problem which I explain better in this post.