是否可以有浅子模块？我有一个包含几个子模块的 super 项目，每个子模块都有很长的历史，所以它不必要地拖着所有的历史。

我找到的只有 this unanswered thread .

我应该只是hack git-submodule实现这个？

最佳答案

即将推出的 git1.8.4 (July 2013) 中的新功能:

"git submodule update" can optionally clone the submodule repositories shallowly.

Add the --depth option to the add and update commands of "git submodule", which is then passed on to the clone command. This is useful when the submodule(s) are huge and you're not really interested in anything but the latest commit.

Tests are added and some indention adjustments were made to conform to the rest of the testfile on "submodule update can handle symbolic links in pwd".

Signed-off-by: Fredrik Gustafsson <iveqy@iveqy.com>
Acked-by: Jens Lehmann <Jens.Lehmann@web.de>

# add shallow submodule
git submodule add --depth 1 <repo-url> <path>
git config -f .gitmodules submodule.<path>.shallow true

# later unshallow
git config -f .gitmodules submodule.<path>.shallow false
git submodule update <path>

git submodule add --depth 1 git@github.com:lorem/ipsum.git path/to/submodule
git config -f .gitmodules submodule.path/to/submodule.shallow true

git config -f .gitmodules submodule.path/to/submodule.shallow true
git submodule add --depth 1 git@github.com:lorem/ipsum.git path/to/submodule

--depth

This option is valid for add and update commands.
Create a 'shallow' clone with a history truncated to the specified number of revisions.

As far as I can tell this option isn't usable for submodules which don't track master very closely. If you set depth 1, then submodule update can only ever succeed if the submodule commit you want is the latest master. Otherwise you get "fatal: reference is not a tree".

submodule: try harder to fetch needed sha1 by direct fetching sha1

When reviewing a change that also updates a submodule in Gerrit, a common review practice is to download and cherry-pick the patch locally to test it.
However when testing it locally, the 'git submodule update' may fail fetching the correct submodule sha1 as the corresponding commit in the submodule is not yet part of the project history, but also just a proposed change.

If $sha1 was not part of the default fetch, we try to fetch the $sha1 directly. Some servers however do not support direct fetch by sha1, which leads git-fetch to fail quickly.
We can fail ourselves here as the still missing sha1 would lead to a failure later in the checkout stage anyway, so failing here is as good as we can get.

It would seem to me that commit fb43e31 requests the missing commit by SHA1 id, so the uploadpack.allowReachableSHA1InWant and uploadpack.allowTipSHA1InWant settings on the server will probably affect whether this works.
I wrote a post to the git list today, pointing out how the use of shallow submodules could be made to work better for some scenarios, namely if the commit is also a tag.
Let's wait and see.

I guess this is a reason why fb43e31 made the fetch for a specific SHA1 a fallback after the fetch for the default branch.
Nevertheless, in case of “--depth 1” I think it would make sense to abort early: if none of the listed refs matches the requested one, and asking by SHA1 isn't supported by the server, then there is no point in fetching anything, since we won't be able to satisfy the submodule requirement either way.

 git config -f .gitmodules submodule.<name>.shallow true

a clone of this submodule will be performed as a shallow clone (with a history depth of 1)

shallow = true on .gitmodules only affects the reference tracked by the HEAD of the remote when using --recurse-submodules, even if the target commit is pointed to by a branch, and even if you put branch = mybranch on the .gitmodules as well.

submodule: support reading .gitmodules when it's not in the working tree

When the .gitmodules file is not available in the working tree, try using the content from the index and from the current branch.
This covers the case when the file is part of the repository but for some reason it is not checked out, for example because of a sparse checkout.

This makes it possible to use at least the 'git submodule' commands which read the gitmodules configuration file without fully populating the working tree.

Writing to .gitmodules will still require that the file is checked out, so check for that before calling config_set_in_gitmodules_file_gently.

Add a similar check also in git-submodule.sh::cmd_add() to anticipate the eventual failure of the "git submodule add" command when .gitmodules is not safely writeable; this prevents the command from leaving the repository in a spurious state (e.g. the submodule repository was cloned but .gitmodules was not updated because config_set_in_gitmodules_file_gently failed).

Moreover, since config_from_gitmodules() now accesses the global object store, it is necessary to protect all code paths which call the function against concurrent access to the global object store.
Currently this only happens in builtin/grep.c::grep_submodules(), so call grep_read_lock() before invoking code involving config_from_gitmodules().

NOTE: there is one rare case where this new feature does not work properly yet: nested submodules without .gitmodules in their working tree.

doc: mention that 'git submodule update' fetches missing commits

^{Helped-by: Junio C Hamano
Helped-by: Johannes Schindelin
Signed-off-by: Philippe Blain}

'git submodule update' will fetch new commits from the submodule remote if the SHA-1 recorded in the superproject is not found. This was not mentioned in the documentation.

The documentation and code have been taught to make more clear recommendations when the users see failures.

submodule--helper: advise on fatal alternate error

^{Signed-off-by: Jonathan Tan
Acked-by: Jeff King}

When recursively cloning a superproject with some shallow modules defined in its .gitmodules, then recloning with "--reference=<path>", an error occurs. For example:

git clone --recurse-submodules --branch=master -j8 \

  https://android.googlesource.com/platform/superproject \
  master
git clone --recurse-submodules --branch=master -j8 \
  https://android.googlesource.com/platform/superproject \
  --reference master master2

fails with:

fatal: submodule '<snip>' cannot add alternate: reference repository

'<snip>' is shallow

When a alternate computed from the superproject's alternate cannot be added, whether in this case or another, advise about configuring the "submodule.alternateErrorStrategy" configuration option and using "--reference-if-able" instead of "--reference" when cloning.

Doc: explain submodule.alternateErrorStrategy

^{Signed-off-by: Jonathan Tan
Acked-by: Jeff King}

Commit 31224cbdc7 ("clone: recursive and reference option triggers submodule alternates", 2016-08-17, Git v2.11.0-rc0 -- merge listed in batch #1) taught Git to support the configuration options "submodule.alternateLocation" and "submodule.alternateErrorStrategy" on a superproject.

If "submodule.alternateLocation" is configured to "superproject" on a superproject, whenever a submodule of that superproject is cloned, it instead computes the analogous alternate path for that submodule from $GIT_DIR/objects/info/alternates of the superproject, and references it.

The "submodule.alternateErrorStrategy" option determines what happens if that alternate cannot be referenced.
However, it is not clear that the clone proceeds as if no alternate was specified when that option is not set to "die" (as can be seen in the tests in 31224cbdc7).
Therefore, document it accordingly.

submodule.alternateErrorStrategy::

Specifies how to treat errors with the alternates for a submodule as computed via submodule.alternateLocation.
Possible values are ignore, info, die.
Default is die.
Note that if set to ignore or info, and if there is an error with the computed alternate, the clone proceeds as if no alternate was specified.

submodule update: silence underlying fetch with "--quiet"

^{Signed-off-by: Nicholas Clark}

Commands such as

$ git submodule update --quiet --init --depth=1

involving shallow clones, call the shell function fetch_in_submodule, which in turn invokes git fetch.
Pass the --quiet option onward there.

关于git - 如何制作浅的 git 子模块？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/2144406/