Many developers don't want to think too much and generally choose Spring boot for a stable, highly-popular and well-documented framework. There is nothing wrong with this choice but I find it too bloated for lean container based micro-services.
Dropwizard and Micronaut are pretty good for getting a smaller and saner footprint. If you need more than REST, say you want a lean MVC-based web-framework, then Blade is also a good choice.
You can also choose not to use a framework and say use code-generation from a swagger/openAPI REST document and implement the remaining bits on your own. If your deployment target is AWS, you can also choose to leverage Netflix's fantastic set of libraries.
Java has tonnes of options, so you usually need to spend some time evaluating what goes into your stack.
I'm curious to hear what specifically is too bloated in Spring Boot in your opinion for container based microservices. I've been writing microservices that run in docker in Java for a few years, then moved to Kotlin recently, all using Spring Boot, and I haven't run into anything that made me feel like they were bloated. I've also written Go and Node microservices for contrast.
Spring boot has a large startup time, heavy dependency trail and a lot of dynamic class-loading based off auto-configuration. This makes it un-suitable for some areas: if you desire fast scaling micro-services that respond quickly to incoming load. Or say you want to transform your micro-service to a server-less function. One can do that with Graal VM to compile your micro-service to a single binary with microscopic start-up time. However, native-image tends to fail more often than not with Spring boot apps. (I haven't tried this recently though so my knowledge could be out of date).
Spring Boot does what it's asked to do, which is to load everything it finds. The dynamic class work has basically nil effect on load time. The core performance constraint is that classes are loaded essentially linearly. If you ship with something enormous like Hibernate, that's thousands of files read individually from a zipfile.
Spring folks are actively involved with Graal. I see a lot of excitement internally at Pivotal. Watch this space.
I'm reminded of the crazy stunts from the 1980s where people would start some big, slow program (Emacs was huge!), dump core, and then "undump" to make a pre-initialized binary that would start as fast as the OS could read it. It actually worked, as long as it wasn't relying on open file descriptors, or signal handlers, or env vars, or …
I’m pretty sure Emacs still does this. There was a patch committed to change it to use a more portable method of dumping state, but I don’t think that change made it into the 26.2 release.
Dropwizard and Micronaut are pretty good for getting a smaller and saner footprint. If you need more than REST, say you want a lean MVC-based web-framework, then Blade is also a good choice.
You can also choose not to use a framework and say use code-generation from a swagger/openAPI REST document and implement the remaining bits on your own. If your deployment target is AWS, you can also choose to leverage Netflix's fantastic set of libraries.
Java has tonnes of options, so you usually need to spend some time evaluating what goes into your stack.