My _service file works. It creates the obscpio and set_version creates the _service spec file that rpmbuild executes. What I’m struggling with is how to convince the default macros to work with it.
People tend to just suggest to avoid set_version and re-compress but that seems a bit wasteful.
I’ve seen the suggestion to call %setup with a different path which works for the %prep phase but then buildroot is still wrong for all the other phases like build install etc.
Why is that when I make a post on an issue I find a solution like 30 minutes later . So the issue was that I had the tar service still in my _service file. Now everything magically works.
I do want to note that the documentation for this is quite hard to find. The documentation for this on openSUSE:Build Service Concept SourceService - openSUSE Wiki is still assuming tar_scm is used which is deprecated. I read the deprecated bit and started using obs_scm and got stuck.
Well, after reading this topic I neither understand what problem you had nor what you did to solve this problem. What about providing description that actually helps others?
I ran into more issues since but the original issue is that obs_scm without re-compress needs to build in %_sourcedir. But by default rpmbuild/obs looks in the BUILD directory for files.
I got %prep working by using %setup -q -n %_sourcedir/%name-%version -T -D but then %build failed as it still looks in the BUILD dir. The reason I guess it was still looking in BUILD dir was because of the tar service I had in the _service file as removing the tar service %build started looking for files (like configure) in %_sourcedir`.
Current issue is that %files/%doc bits are failing as they are looking for things in BUILD again .
. So the issue was that I had the tar service still in my 
.
. It somehow knows it has to look in the source dir but then prefixes it with the buildroot path.