[wishlist] support of cloning recursively from non-bare submodule hierarchies?

[wishlist] support of cloning recursively from non-bare submodule hierarchies?

[Yaroslav Halchenko]

Example - on http://datasets.datalad.org we have a few hundred datasets
organized into a hierarchy as git submodules.  Each  git submodules carries its
own .git/ directory so they are "self sufficient" and we could readily assess
their sizes, and "cut the tree" at any level without looking for the
supermodule somewhere high up in the tree.

.gitmodules typically has relative paths for the url and path for the
submodules there, the form which I think we chose because it used to work (I
could be utterly wrong! but I think it was done in an informed fashion)
for git clone --recursive:

	$> curl http://datasets.datalad.org/labs/gobbini/famface/.gitmodules
	[submodule "data"]
		path = data
		url = ./data

and possibly outside:

	$> curl http://datasets.datalad.org/labs/gobbini/famface/data/.gitmodules 
	[submodule "scripts/mridefacer"]
		path = scripts/mridefacer
		url = https://github.com/yarikoptic/mridefacer

But unfortunately git doesn't even consider such (valid AFAIK) situation
while cloning where url has to have .git suffix but repository is not bare and
a relative "data" path (or "./data" url) is referring to the worktree.

	$> git clone --recursive http://datasets.datalad.org/labs/gobbini/famface/.git 
	Cloning into 'famface'...
	remote: Counting objects: 61, done.
	remote: Compressing objects: 100% (54/54), done.
	remote: Total 61 (delta 14), reused 0 (delta 0)
	Unpacking objects: 100% (61/61), done.
	Submodule 'data' (http://datasets.datalad.org/labs/gobbini/famface/.git/data) registered for path 'data'
	Cloning into '/tmp/famface/data'...
	fatal: repository 'http://datasets.datalad.org/labs/gobbini/famface/.git/data/' not found
	fatal: clone of 'http://datasets.datalad.org/labs/gobbini/famface/.git/data' into submodule path '/tmp/famface/data' failed
	Failed to clone 'data'. Retry scheduled
	Cloning into '/tmp/famface/data'...
	fatal: repository 'http://datasets.datalad.org/labs/gobbini/famface/.git/data/' not found
	fatal: clone of 'http://datasets.datalad.org/labs/gobbini/famface/.git/data' into submodule path '/tmp/famface/data' failed
	Failed to clone 'data' a second time, aborting

on the server I use the "smart HTTP" git backend, but not sure if that is the one to blame, since
I do not see in the logs any attempt to get the /data from not under .git/:

	10.31.188.88 - - [13/Dec/2018:12:18:38 -0500] "GET /labs/gobbini/famface/.git/info/refs?service=git-upload-pack HTTP/1.1" 200 681 "-" "git/2.20.0.rc2.403.gdbc3b29805"
	10.31.188.88 - - [13/Dec/2018:12:18:38 -0500] "POST /labs/gobbini/famface/.git/git-upload-pack HTTP/1.1" 200 69276 "-" "git/2.20.0.rc2.403.gdbc3b29805"

	==> datasets.datalad.org-error.log <==
	[Thu Dec 13 12:18:38.673447 2018] [core:info] [pid 7570:tid 140683541153536] [client 10.31.188.88:32794] AH00128: File does not exist: /srv/datasets.datalad.org/www/labs/gobbini/famface/.git/data/info/refs

	==> datasets.datalad.org-access-comb.log <==
	10.31.188.88 - - [13/Dec/2018:12:18:38 -0500] "GET /labs/gobbini/famface/.git/data/info/refs?service=git-upload-pack HTTP/1.1" 404 485 "-" "git/2.20.0.rc2.403.gdbc3b29805"

	==> datasets.datalad.org-error.log <==
	[Thu Dec 13 12:18:38.689277 2018] [core:info] [pid 7572:tid 140683574724352] [client 10.31.188.88:32796] AH00128: File does not exist: /srv/datasets.datalad.org/www/labs/gobbini/famface/.git/data/info/refs

	==> datasets.datalad.org-access-comb.log <==
	10.31.188.88 - - [13/Dec/2018:12:18:38 -0500] "GET /labs/gobbini/famface/.git/data/info/refs?service=git-upload-pack HTTP/1.1" 404 485 "-" "git/2.20.0.rc2.403.gdbc3b29805"


-- 
Yaroslav O. Halchenko
Center for Open Neuroscience     http://centerforopenneuroscience.org
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
WWW:   http://www.linkedin.com/in/yarik        

Re: [wishlist] support of cloning recursively from non-bare submodule hierarchies?

[Stefan Beller]

On Thu, Dec 13, 2018 at 9:19 AM Yaroslav Halchenko <yoh@onerussian.com> wrote:
>
> Example - on http://datasets.datalad.org we have a few hundred datasets
> organized into a hierarchy as git submodules.  Each  git submodules carries its
> own .git/ directory so they are "self sufficient" and we could readily assess
> their sizes, and "cut the tree" at any level without looking for the
> supermodule somewhere high up in the tree.
>
> .gitmodules typically has relative paths for the url and path for the
> submodules there, the form which I think we chose because it used to work (I
> could be utterly wrong! but I think it was done in an informed fashion)
> for git clone --recursive:
>
>         $> curl http://datasets.datalad.org/labs/gobbini/famface/.gitmodules
>         [submodule "data"]
>                 path = data
>                 url = ./data
>
> and possibly outside:
>
>         $> curl http://datasets.datalad.org/labs/gobbini/famface/data/.gitmodules
>         [submodule "scripts/mridefacer"]
>                 path = scripts/mridefacer
>                 url = https://github.com/yarikoptic/mridefacer

So far so good.

> But unfortunately git doesn't even consider such (valid AFAIK) situation
> while cloning where url has to have .git suffix but repository is not bare and
> a relative "data" path (or "./data" url) is referring to the worktree.
>
>         $> git clone --recursive http://datasets.datalad.org/labs/gobbini/famface/.git
[..]
>         Submodule 'data' (http://datasets.datalad.org/labs/gobbini/famface/.git/data) registered for path 'data'

and here it goes wrong, and you would have expected to see
.../gobbini/famface/data, eliding the .git ?

I just checked and this did not work neither in v2.18.0 nor v2.0.0 of
Git, so it is
either a real old regression in submodules, or something else.
Is it possible that the clone worked once without the additional .git
in the superproject URL?

> on the server I use the "smart HTTP" git backend, but not sure if that is the one to blame, since
> I do not see in the logs any attempt to get the /data from not under .git/:

If we want to strip off "/.git" of urls to make submodules work,
we'd want to look at builtin/submodule--helper.c::compute_submodule_clone_url
that was recently introduced.

I wonder if we'd just want to cut off the "/.git" and assume the submodule
is there in the worktree. Or if we need to see if the submodule was
absorbed into .git/modules/<name> on the remote side. (But if the
submodule is checked out both would work)