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Re: [RFC 00/10] Make .the gitmodules file path configurable

From
Antonio Ospite <ao2@ao2.it>
Date
Apr 30, 2018, 12:51 UTC
Message-ID
<20180430145114.3c68c026b1e2844aaa9d4b6d@ao2.it>
In-Reply-To
<20180423174709.GA25128@aiede.svl.corp.google.com>

On Mon, 23 Apr 2018 10:47:09 -0700 Jonathan Nieder <jrnieder@gmail.com> wrote:

> Hi,
>
Hi Jonathan, thank you for your comment.
Show 8 quoted lines
> Antonio Ospite wrote:
> 
> > vcsh[1] uses bare git repositories and detached work-trees to manage
> > *distinct* sets of configuration files directly into $HOME.
> 
> Cool!  I like the tooling you're creating for this, though keep in mind
> that Git has some weaknesses as a tool for deployment.
>

I am not the author BTW, just a user trying to address the remaining corner cases.

> In particular, keep in mind that when git updates a file, there is a
> period of time while it is missing from the filesystem, which can be
> problematic for dotfiles.
>

Thanks for the reminder, it may be worth mentioning this in vcsh documentation, however I don't have knowledge of users experiencing problems related to that.

Show 36 quoted lines
> [...]
> > However when multiple repositories take turns using the same directory
> > as their work-tree, and more than one of them want to use submodules,
> > there could still be conflicts about the '.gitmodules' file because git
> > hardcodes this path.
> >
> > For comparison, in case of '.gitignore' a similar conflict might arise,
> > but git has alternative ways to specify exclude files, so vcsh solves
> > this by setting core.excludesFile for each repository and track ignored
> > files somewhere else (in ~/.gitignore.d/$VCSH_REPO_NAME).
> 
> For reference:
> 
> 	core.excludesFile
> 		Specifies the pathname to the file that contains
> 		patterns to describe paths that are not meant to be
> 		tracked, in addition to .gitignore (per-directory) and
> 		.git/info/exclude. Defaults to
> 		$XDG_CONFIG_HOME/git/ignore. If $XDG_CONFIG_HOME is
> 		either not set or empty, $HOME/.config/git/ignore is
> 		used instead. See gitignore(5).
> 
> Using this as a substitute for <worktree>/.gitignore is a bit of a
> hack.  It happens to work, though, so reading on. :)
> 
> [...]
> > So this series proposes a mechanism to set an alternative path for the
> > submodules configuration file (from now on "gitmodules file").
> 
> I am nervous about this.  I wonder if there is another way to
> accomplish the goal.
>
> One possibility would be to handle the case where .gitmodules is
> excluded by a sparse checkout specification and use .gitmodules from
> the index in that case.  Would that work for you?
>

Since part of the problem is that .gitmodules *collide* between repositories, a sparse-checkout approach make sense indeed.

As discussed[1] with Stefan Beller having git use .gitmodules from the index without the need to have it checked out should work for us.

[1] https://www.spinics.net/lists/git/msg329153.html

Ideally git should also be able to write to that file when it's not checked out (e.g. when running "git submodule add"), to save the user from tedious sparse/unsparse rounds when operating with submodules.

As suggested by Stefan I'll first try to remove the hardcoded references to .gitmodules in git-submodule.sh adding a helper sub-command to access .gitmodules in a more robust way, and after that git could be taught to use the file from the index, but this second part is currently beyond my current git knowledge.

If this mechanism of using unchecked-out files from the index could be extended to .gitignore (and .gitattributes), then vcsh might even stop abusing core.excludesFile; sparse checkouts seem the more natural git way to deal with colliding files in a shared-workdir scenario.

However, having users *write* to .gitignore and .gitattributes while they are not checked out still sounds quite problematic to me, but maybe this could be handled by vcsh itself, similarly to what is done for the file pointed by core.excludesFile.

Ciao,
   Antonio
-- 
Antonio Ospite
https://ao2.it
https://twitter.com/ao2it

A: Because it messes up the order in which people normally read text.
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Previous: Jonathan Nieder
Message 28 of 28 in “[RFC 00/10] Make .the gitmodules file path configurable”
  1. Antonio OspiteApr 12, 2018
  2. 03/10 submodule: use the 'submodules_file' variable in output messagesAntonio Ospite, Apr 12, 2018
  3. 02/10 submodule: fix getting custom gitmodule file in fetch commandAntonio Ospite, Apr 12, 2018
  4. Stefan BellerApr 12, 2018
  5. Antonio OspiteApr 16, 2018
  6. Stefan BellerApr 16, 2018
  7. Antonio OspiteApr 16, 2018
  8. 01/10 submodule: add 'core.submodulesFile' to override the '.gitmodules' pathAntonio Ospite, Apr 12, 2018
  9. Stefan BellerApr 12, 2018
  10. Antonio OspiteApr 16, 2018
  11. Stefan BellerApr 16, 2018
  12. Antonio OspiteApr 18, 2018
  13. Stefan BellerApr 18, 2018
  14. 04/10 submodule: document 'core.submodulesFile' and fix references to '.gitmodules'Antonio Ospite, Apr 12, 2018
  15. 05/10 submodule: adjust references to '.gitmodules' in commentsAntonio Ospite, Apr 12, 2018
  16. 06/10 completion: add 'core.submodulesfile' to the git-completion.bash fileAntonio Ospite, Apr 12, 2018
  17. Stefan BellerApr 12, 2018
  18. Antonio OspiteApr 16, 2018
  19. Stefan BellerApr 16, 2018
  20. Antonio OspiteApr 13, 2018
  21. 07/10 FIXME: wrap-for-bin.sh: set 'core.submodulesFile' for each git invocationAntonio Ospite, Apr 13, 2018
  22. 09/10 FIXME: submodule: pass custom gitmodules file to 'test-tool submodule-config'Antonio Ospite, Apr 13, 2018
  23. 10/10 FIXME: add a hacky script to test the changes with a patched test suiteAntonio Ospite, Apr 13, 2018
  24. 08/10 FIXME: submodule: fix t1300-repo-config.sh to take into account the new configAntonio Ospite, Apr 13, 2018
  25. Stefan BellerApr 13, 2018
  26. Antonio OspiteApr 16, 2018
  27. Jonathan NiederApr 23, 2018
  28. Antonio OspiteApr 30, 2018

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