I am wondering if you can provide some information on how various companies are deploying Spring Boot FATJAR into their production environments? Are people using init.id, docker, etc..? If so what seems to be the most popular deployment mechanism?
Anywhere an executable JAR can run is a candidate for running JAR-based Spring Boot apps. The two most common I hear about are in Docker containers and in CloudFoundry. But if you can run an executable JAR, then any environment will work.
That said, you can still use Spring Boot in more traditional containers by building them into WAR files. Truly, the only major differences between a Spring Boot app in a JAR vs. one in a WAR is that the WAR version has an additional class that extends SpringBootServletInitializer and has a build file that produces a WAR instead of a JAR. The rest of the code can be pretty much the same. The subclass of SpringBootServletInitializer serves as the app's web.xml file, so there's no need to create a web.xml file...but this also means that you must deploy into a Servlet 3.0 (or higher) container. That shouldn't be much of an issue as Servlet 3.0 has been around for over 6 years. Only if you're working in an older container will that be a problem (and you should really consider updating).