Libelektra: remove entry barriers

For me it was the installing of elektra without root.
Installing without root requires a few cmake flags (KDB_DB_SYSTEM, CMAKE_INSTALL_PREFIX, ...) and env variables (LD_LIBRARY_PATH, ..) to be set. Although CMAKE_INSTALL_PREFIX is described in doc/COMPILE, it wasn't obvious to me which cmake flags and envs need to be set for this.
In doc/Testing.md in the section "You have some options to avoid running them as root:", following example cmake invocation is referenced: scripts/configure-home (should btw actually be scripts/dev/configure-home). This example only covers compiling and not installing (CMAKE_INSTALL_PREFIX flag is missing). Since kdb run_all is also described in doc/TESTING.md, it should, at least in my opinion, be also mentioned how to get this working without root.

The steps in doc/tutorials/run_all_tests_with_docker.md - which is actually referenced in doc/TESTING.md - describe how to install it as non-root user, but it is not mentioned that the docker images are run as non-root. So it was in the beginning a little unclear to me why these things needed to be set only here.

I would propose to:

• add a description that the docker images are run as non-root (and maybe also the reason for this).
• add a point to doc/INSTALL.md and/or doc/TESTING.md on how to install elektra without root privileges.

Thank you very much for this very helpful input!

Although CMAKE_INSTALL_PREFIX is described in doc/COMPILE

Yes, I fully agree, this docu must be rewritten to a style where concrete problems are solved (like installing without root). The sole description of what the flags do is better done within the CMake-cache-variable-docu.

but it is not mentioned that the docker images are run as non-root

I hope you can improve the tutorials about Docker images :sparkling_heart:, you need to adapt them anyway with the changes you make (like removing the need for the Jenkins user).

docker images are run as non-root (and maybe also the reason for this).

Do you mean the reason why they run as non-root? It is best practice to run something with the minimal amount of privileges as possible.

In general: It is good if we do not assume too much knowledge about Docker or Jenkins in our docu, as many people do not have it. So I agree, that such rationale should be given.

I hope you can improve the tutorials about Docker images 💖, you need to adapt them anyway with the changes you make (like removing the need for the Jenkins user).

Yes of course I will improve the tutorials about the Docker images.