git bug: Including a git repository in a directory

git bug: Including a git repository in a directory

[Steven Jonn Edlefsen]

Git cannot commit/push a directory with a git repository in
a sub-directory.

The sub-directory with the git repository and the directories below
are set to the “master” branch, while the directories above remain
set to the new branch.

When the top directory is committed, the sub-directory with the
git repository appears as an empty file.

Even when the subdirectory branch name is changed from master
to the new branch and the top directory is re-commited/pushed,
the same problem occurs.

When the git repository in the sub-directory is removed, e.g.
the .git file is removed, and top directory is committed/pushed,
the subdirectory has all the sub-directories and files.

Steve Edlefsen

Re: git bug: Including a git repository in a directory

[René Scharfe]

Am 06.06.22 um 07:43 schrieb Steven Jonn Edlefsen:
> Git cannot commit/push a directory with a git repository in
> a sub-directory.
>
> The sub-directory with the git repository and the directories below
> are set to the “master” branch, while the directories above remain
> set to the new branch.
>
> When the top directory is committed, the sub-directory with the
> git repository appears as an empty file.
>
> Even when the subdirectory branch name is changed from master
> to the new branch and the top directory is re-commited/pushed,
> the same problem occurs.
>
> When the git repository in the sub-directory is removed, e.g.
> the .git file is removed, and top directory is committed/pushed,
> the subdirectory has all the sub-directories and files.

This is intended behavior.  A repository inside another one needs
special handling.  Git provides the submodule feature for that.  A
simpler alternative for some use cases is called subtree.

That's all I can tell you, as I haven't used submodules and subtrees
myself.  At least I hope these keywords help you explore your options.
Others will probably chime in with advise on which one to use if you
explain _why_ you want to combine multiple repositories.

René

Re: git bug: Including a git repository in a directory

[Glen Choo]

Hi!

René Scharfe <l.s.r@web.de> writes:

> Am 06.06.22 um 07:43 schrieb Steven Jonn Edlefsen:
>> Git cannot commit/push a directory with a git repository in
>> a sub-directory.
>>
>> The sub-directory with the git repository and the directories below
>> are set to the “master” branch, while the directories above remain
>> set to the new branch.
>>
>> When the top directory is committed, the sub-directory with the
>> git repository appears as an empty file.
>>
>> Even when the subdirectory branch name is changed from master
>> to the new branch and the top directory is re-commited/pushed,
>> the same problem occurs.
>>
>> When the git repository in the sub-directory is removed, e.g.
>> the .git file is removed, and top directory is committed/pushed,
>> the subdirectory has all the sub-directories and files.
>
> This is intended behavior.  A repository inside another one needs
> special handling.  Git provides the submodule feature for that.  A
> simpler alternative for some use cases is called subtree.

As René described, this is intended behavior - repositories cannot
contain entire repositories with `.git` inside them [1]. As far as I
know, this is security feature because `.git` can contain sensitive
files that you wouldn't want to clone down, e.g. .git/config can make
"git" execute arbitrary code.

What happened in your case is that Git noticed that the subdirectory is
a repository and automatically 'sanitizes' it for you by converting it
into (what is essentially) a submodule [2]. When a subdirectory is a
submodule, Git stores a single commit id for the entire subdirectory -
you you can no longer change individual files inside the subdirectory.

To demonstrate this "single commit id" behavior, this is what happens if
you tried to `git init` a subdirectory in an existing project:

  $ git init foo
  Initialized empty Git repository in /Users/chooglen/Code/repo/foo/.git/
  $ git add foo
  error: 'foo/' does not have a commit checked out

Notice the line above! We can't add `foo` because it has been converted
into a (pseudo) submodule [2].

  $ (cd foo && git commit -m "foo" --allow-empty) # create a commit
  [main (root-commit) 9e27581] foo
  $ git add foo
  warning: adding embedded git repository: foo
  hint: You've added another git repository inside your current repository.
  hint: Clones of the outer repository will not contain the contents of
  hint: the embedded repository and will not know how to obtain it.
  hint: If you meant to add a submodule, use:
  hint:
  hint:   git submodule add <url> foo
  hint:
  hint: If you added this path by mistake, you can remove it from the
  hint: index with:
  hint:
  hint:   git rm --cached foo
  hint:
  hint: See "git help submodule" for more information.
  $ git diff HEAD 
  diff --git a/foo b/foo
  new file mode 160000
  index 0000000..9e27581
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1 @@
  +Subproject commit 9e27581b9eb91c0f1699eb18a2e81d758de9209d

Now that there is a commit in the subdirectory repository we can `git
add` it, but only as an entire commit. We cannot just add individual
files.

If you truly need a repository inside of another repository. You may
want to consider submodules/subtrees as René mentioned.

[1] A repository can contain a "bare" repository because a bare
repository does not have `.git`, but that isn`t relevant to the
discussion here.
[2] A submodule technically also has to have an entry in the .gitmodules
file.