Can I use git submodule within the same repository?

Question

In my project there is a folder with common tools that I want to include in each of my app components. I just want one master version of it and I want the rest of the copies to be updated with git commands as normal. Is there a way to do this while keeping everything in the same repository? I know got submodule works with multiple repositories but it doesn't seem like it works with just a single repository. Does anyone have any insight on the matter?

Answer 1

In my project there is a folder with common tools that I want to include in each of my app components. I just want one master version of it and I want the rest of the copies to be updated with git commands as normal. Is there a way to do this while keeping everything in the same repository? I know got submodule works with multiple repositories but it doesn't seem like it works with just a single repository. Does anyone have any insight on the matter?

Answer 2

Experimenting a little, the answer seems to be "sort-of". The command supports it with something like

git submodule add -b libfoo -- ./ libs/foo

where libfoo is the name of the branch that the submodule exists in, ./ is a relative URL to the "upstream repository", and libs/foo is the "working tree" of the submodule checkout (and also the default name of the submodule; you may want to override this with --name libfoo ).

Digging around a little, it doesn't quite do what you might want:

• It seems to do a ~full checkout (with all the remote tracking branches, not just the submodule branch).
  • You can probably fix this by editing .git/modules/libs/foo/config .
• It does not share storage with the "enclosing" repo.
  • You can probably make it share storage with symlinks (as git-new-workdir does).
  • I'm less sure about making this share storage in the same way as git worktree . Maybe this is just a matter of pointing .git/modules/libs/foo/commondir at the enclosing repo?
• If you have an origin (aka upstream?) set, I think the branch must already exist on the origin repo.
• If you don't have an origin set, it uses the absolute path of the local repo as the origin "URL" of the submodule (see .git/modules/libs/foo/config ). This will break if you move your checkout somewhere else on the filesystem.

git-subtrac (from the author of git-subtree) is designed around the "submodules in the same repo" idea, but I'm not sure how much it helps with the above.