Added support for git submodules.

[leander-dsouza]

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#272
Primary OS tested on	Ubuntu
Is this a breaking change?	No
Does this PR contain AI generated software?	No

---

Description of contribution in a few bullet points

• Since submodules have .git as a file instead of a folder, this change accounts for detecting it as a repository to clone into.

Description of how this change was tested

• Initialise a submodule locally within the repository under a temp folder.

  mkdir temp && cd temp
  git submodule add https://github.com/dirk-thomas/vcstool.git

• Compare the contents of repo.yaml before and after this change:

  cd vcs2l
  vcs export --nested > repos.yaml

• Final result of the YAML file:

  repositories:
    vcs2l:
      type: git
      url: [email protected]:ros-infrastructure/vcs2l.git
      version: leander-dsouza/add-submodule-support
    vcs2l/temp/vcstool:
      type: git
      url: https://github.com/dirk-thomas/vcstool.git
      version: daf389377310f7f31b2171f51a79af82c31bf3e2

  The submodule would not have been detected if this change were not present.

Signed-off-by: Leander Stephen Desouza [email protected]

[claraberendsen]

Thanks for porting this over.
I think we should approach submodules by recognizing them by .gitsubmodules instead of checking if the .git is a file or a dir.
Additionally I have questions on how this behaves when doing a vcs pull and vcs import since there is no specific recognition on the output that these are submodules directories.

[claraberendsen]

I think we should conform to recognizing submodules as how they are defined in the parent repository. On git this is by using the .gitmodules file in the parent repository. See https://git-scm.com/docs/gitmodules.

If you check the contents of the .git file that you are recognizing it is a link to the git dir on ../../.git/modules.

With the example from the test of this PR:

cat .git
gitdir: ../../.git/modules/temp/vcstool

[leander-dsouza]

Currently, the --nested flag for vcs export, recursively searches all the subdirectories of the parent directory and determines if the directory is a repository by using the is_repository function.

I guess when the --nested flag is active, instead of using recursion, this would be cleaner to determine all the submodules from the .gitmodules file.

[christophebedard]

@leander-dsouza just a thought, but you might want to ping the original author of PRs that you port over. They may have been using a given feature internally and could have interesting feedback to share.

[leander-dsouza]

Additionally I have questions on how this behaves when doing a vcs pull and vcs import since there is no specific recognition on the output that these are submodules directories.

• vcs pull also uses the same --nested flag to search for submodules to pull from. Therefore, this would rectify the behaviour of this command as well.

• vcs import, however, uses a different --recursive flag to import submodules, and is unaffected by this change.

[leander-dsouza]

Hello @varunsairam, just a gentle ping on this PR :)

I was wondering if you could take a look at this PR and probably describe an internal use case for the change, as this is a direct port of your contribution over at vcstools.

[leander-dsouza]

@leander-dsouza just a thought, but you might want to ping the original author of PRs that you port over. They may have been using a given feature internally and could have interesting feedback to share.

Thank you for the advice, Christophe :)