I realize that the situation on Linux is very new for Microsoft but the current state after this much time is quite sad.
In the transition to msbuild projects they mixed-up the runtime versions.
The documentation on using docker is wrong and very confusing - the Microsoft web site and the instructions on docker hub are not the same!
The SDK image is broken, it seems to assume a Windows docker host - it tries to compile with the .Net Framework on Linux!
Publish a 5 line "hello world" program to a docker core runtime and you'll get a 250MB image.
Try running more than a couple of those in a microservice configuration ... I hope you have deep pockets.
I can't say that I'm enthusiastic about the move to msbuild. After too many years of that on Windows I was hoping they would have seen the error of their ways.
I do think there's definitely an opportunity to streamline this, and separate the commit for the libraries from nuget, and the output from the build process... If they can automate this, all the better... I was pretty happy basing from the *-onbuild and it just built the project nicely and ran... but if you're constrained on space, I can definitely see this becoming wasteful very quickly.