GIT_WORK_TREE and GIT_DIR with git clone

GIT_WORK_TREE and GIT_DIR with git clone

[Cosmin Apreutesei]

Hi,

I would like to have git clone respect GIT_DIR (and --git-dir) so I
can clone multiple repos into the same working directory (I know there
was another request for this[1]).

The pattern here is big projects that are modularized into multiple
git repositories, but supposed to be overlaid over a common directory
structure.

I would like to be able to tell my users that they can simply do:

git clone --git-dir=_/git/module1/.git module1-url
git clone --git-dir=_/git/module2/.git module2-url

which will overlay the files from both modules into the current
directory, which from git's perspective is the work-tree for both
modules.


[1] http://article.gmane.org/gmane.comp.version-control.git/170073/match=git_work_tree+git_dir+git+clone

Re: GIT_WORK_TREE and GIT_DIR with git clone

[Junio C Hamano]

Cosmin Apreutesei <cosmin.apreutesei@gmail.com> writes:

> I would like to be able to tell my users that they can simply do:
>
> git clone --git-dir=_/git/module1/.git module1-url
> git clone --git-dir=_/git/module2/.git module2-url
>
> which will overlay the files from both modules into the current
> directory, which from git's perspective is the work-tree for both
> modules.

Would there be a sensible semantics in the resulting working tree?
Which repository would a new file in such a combined working tree
belong to?

Re: GIT_WORK_TREE and GIT_DIR with git clone

[Cosmin Apreutesei]

Hi, thanks for answering.

>> I would like to be able to tell my users that they can simply do:
>>
>> git clone --git-dir=_/git/module1/.git module1-url
>> git clone --git-dir=_/git/module2/.git module2-url
>>
>> which will overlay the files from both modules into the current
>> directory, which from git's perspective is the work-tree for both
>> modules.
>
> Would there be a sensible semantics in the resulting working tree?
> Which repository would a new file in such a combined working tree
> belong to?

The developer would have to decide by way of `git add`.

Ignoring other repos' files would be done by way of local config
option `excludesfile` (.gitignore is out).

To make it easier to work with git this way, a script that creates a
subshell in the context of a repo can be done with something like
`PS1="[$1 $PS1]" GIT_DIR=_git/$1/.git bash -i" -- git would then work
as usual in that subshell for that specific repo, never leaving the
working tree.


I successfully employed the above scheme with luapower[1] packages,
which are all different and mostly unrelated libraries, but which need
to be overlaid over a common directory structure. And that's just an
example. I can think of many projects that are modularized and yet the
modules need to place many files in many places to make a working
system (web frameworks, the linux filesystem, etc.)

Currently, to clone a repo one has to do:

export GIT_DIR=_git/submodule/.git
git init
git config --local core.worktree ../../..
git remote add origin ssh://git@github.com/luapower/submodule.git
git fetch
git branch --track master origin/master
git checkout

That's 6 commands for what could be:

    git clone --git-dir=_git/submodule/.git
ssh://git@github.com/luapower/submodule.git

Or even better:

    git clone --git-dirs=_git ssh://git@github.com/luapower/submodule.git

[1] http://luapower.com

GIT_WORK_TREE and GIT_DIR with git clone

[Kacper Kornet]

Is there a reason why git clone does not respect GIT_DIR
variable. I have found it confusing that:

GIT_WORK_TREE=repo GIT_DIR=repo/.git git clone <path>/repo.git

is not equivalent to

git clone <path>/repo.git

-- 
  Kacper

Re: GIT_WORK_TREE and GIT_DIR with git clone

[Junio C Hamano]

Kacper Kornet <kornet@camk.edu.pl> writes:

> Is there a reason why git clone does not respect GIT_DIR
> variable.

Are you sure it does "not respect GIT_DIR"?  When you are running clone
locally, like that:

> GIT_WORK_TREE=repo GIT_DIR=repo/.git git clone <path>/repo.git

you have _two_ repositories that the command operates on on your system,
the one that you are cloning _from_, and the new one that you are
creating.

Which repository does your GIT_DIR talk about?

Re: GIT_WORK_TREE and GIT_DIR with git clone

[Kacper Kornet]

On Sat, Mar 26, 2011 at 12:40:58PM -0700, Junio C Hamano wrote:
> Kacper Kornet <kornet@camk.edu.pl> writes:

> > Is there a reason why git clone does not respect GIT_DIR
> > variable.

> Are you sure it does "not respect GIT_DIR"?  When you are running clone
> locally, like that:

> > GIT_WORK_TREE=repo GIT_DIR=repo/.git git clone <path>/repo.git

> you have _two_ repositories that the command operates on on your system,
> the one that you are cloning _from_, and the new one that you are
> creating.

> Which repository does your GIT_DIR talk about?

I would expect that GIT_DIR always talks the new one. For example after:

GIT_WORK_TREE=dir GIT_DIR=dir/.git git clone git://git.kernel.org/pub/scm/gitk/gitk

I would expect to have repo in dir/.git. What happens is that in dir
there is a working tree and in local directory gitk there is a bare
repo. The following patch should fix the issue:

diff --git a/builtin/clone.c b/builtin/clone.c
index c6e10bb..082ee53 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -442,11 +442,14 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 			die("working tree '%s' already exists.", work_tree);
 	}
 
-	if (option_bare || work_tree)
-		git_dir = xstrdup(dir);
-	else {
+	git_dir = getenv("GIT_DIR");
+	if (option_bare || work_tree) {
+		if (!git_dir)
+			git_dir = xstrdup(dir);
+	} else {
 		work_tree = dir;
-		git_dir = xstrdup(mkpath("%s/.git", dir));
+		if (!git_dir)
+			git_dir = xstrdup(mkpath("%s/.git", dir));
 	}
 
 	if (!option_bare) {





-- 
  Kacper