Question

I’d like to create a new repository as a submodule of my project.

Usually, I create a Github repo and then add it as a submodule using the command
git submodule add url_to_repo.git

Is there a way to create a new repo directly as a submodule without creating the repo somewhere else first (neither locally nor remote e.g. on Github)?

Answer 1

I don’t see how you could: a submodule is by definition a SHA1 from another repo (ie the other repo must exist for the parent repo to extract said SHA1): you must have its address referenced in the .gitmodules file that you keep in the parent repo.

Submodules are composed from a so-called gitlink tree entry in the main repository that refers to a particular commit object within the inner repository that is completely separate.

submodule.<name>.url

Defines a URL from which the submodule repository can be cloned. This may be either an absolute URL ready to be passed to git-clone(1) or (if it begins with ./ or ../) a location relative to the superproject’s origin repository.

So you could create the submodule repo locally, but you must create it anyway.