using git-submodule without repository structure modification

Question

I have two github repository similar to the below structure as an example:

repo1: [folder_X] fileA fileB fileC fileD [folder_Y] fileE fileF

repo2: [folder_M] fileB fileC fileK [folder_N] fileO fileP

as you see in both repository we have some common files in folder_X and folder_M which are fileB and fileC. I need to have a common source for these files, so I don't need to modify them in two repository always. These common files (B and C) can be stored in a separate branch in repo1 as an example.

Is there any solution for it without modifying the repo structure?

Answer 1

If you insist on using git submodules, then note that it works on a repository basis, i.e. you can only attach the full repository tree as a subfolder of another repository. You can't filter it, i.e. you get the full repository from the root folder with all the files and subfolders. Thus a clean way would be to create a repo3 with common files, and link it as a submodule to repo1 and repo2.

Another possible way is if you treat repo1 as a provider of common files, and repo2 as a derivative project (consumer). Then you can link repo1 as a submodule of repo2, and then modify the repo2 to reference files inside repo1 subfolder. This can be either a modification of project files or build scripts, or just symlinks.

A third way is to not use git submodules, but use some package manager. For example, some package managers support creating a package with just a few files out of a repository, and then you can reuse that package from another repo.