Subject: Re: Submodules and GIT_ALTERNATE_OBJECT_DIRECTORIES

From: Jens Lehmann <[email-masked]>
Date: Sat, 04 Oct 2014 20:03:51 +0200

Am 03.10.2014 um 13:56 schrieb Michal Sojka:
> On Fri, Oct 03 2014, Jens Lehmann wrote:
>> Am 30.09.2014 um 15:25 schrieb Michal Sojka:
>>> I'd like to shorten the time needed by our continuous integration (CI)
>>> tool to clone the source repositories. Currently the full clone takes
>>> about 10 minutes (even from local server). Our main repository has
>>> several submodules so the CI tool runs "git submodule update --init". My
>>> idea was to use GIT_ALTERNATE_OBJECT_DIRECTORIES to cache objects from
>>> several submodule repositories locally. However, this does not work
>>> because GIT_ALTERNATE_OBJECT_DIRECTORIES is considered local to the
>>> super-project and is not propagated to the "git clone" for submodules
>>> (git-submodule.sh calls clear_local_git_env).
>>   >
>>> My question is why is GIT_ALTERNATE_OBJECT_DIRECTORIES considered local
>>> to the repository? If I could modify the command-line I would use the
>>> "git submodule update" with the --reference option, which is propagated
>>> to clones of all submodules. Letting GIT_ALTERNATE_OBJECT_DIRECTORIES
>>> propagate to the submodules should have the same effect as --reference
>>> option. So why it is not propagated?
>>
>> Because then it would /always/ propagate? So while that would have the
>> same effect as using the --reference option, not using the --reference
>> option would behave differently, no?
>
> That's a good reason, thanks. Fortunately, I found a way how to add
> --reference to the submodule update command issued by the CI tool
> (Bamboo). Instead of calling git directly, the CI tool calls my "git"
> script, which modifies the command line in case of "submodule update"
> and then calls the real git.

Good to hear that! In the CI tool we use at $dayjob (Jenkins) we do
not use the automatic submodule update provided by the Git plugin
but call submodule update in the shell execution before building it.