If you want to containerize a java app check out jib. Really easy to use and integrates well with gradle
From what I can tell "containerization" is mostly just starting up a Docker image, running apt-get or equivalent to install tools (in this case, a JVM), and specifying a launch script or entry point. You might give it some arguments for what ports and volumes to mount.
Is there more to it? Because that kind of thing doesn't seem to require more than a simple script or two, and I have a hard time understanding why you need dedicated tools for this.
A few years ago I wrote up a scheme (which wasn't pursued) for automatic image construction[0]. The first half of the writeup enumerated a bunch of problems with relying purely on Dockerfiles.
[0] https://docs.google.com/document/d/1M2PJ_h6GzviUNHMPt7x-5POU...
After you run
dotnet publish
I never bothered to go through the manually steps. I used the CF template above.
Here is the complete Docker file for containerizing an ASP.Net Core API.
FROM microsoft/aspnetcore:2.0
WORKDIR /mymvcweb
COPY bin/Release/netcoreapp2.0/publish .
ENV ASPNETCORE_URLS http://+:5000
EXPOSE 5000
ENTRYPOINT ["dotnet", "mymvcweb.dll"]
Here is the CF Template:
But where that's not the operational setup, JARs on app servers are perfectly fine, IMO.