202

I have two SVN projects in use from another SVN repository using svn:externals.

How can I have the same repository layout structure in Git?

Improve this question
5
  • You should look into Git submodules. It should allow almost exactly what you're looking for. Commented Feb 20, 2009 at 21:32
  • 11
    Anyone have a new answer to this in the last 4 years, or is the world of git the same today? Commented Apr 19, 2013 at 23:37
  • 5
    @DougW Yes, I have a new answer below: git submodule can now emulate svn:external (since March 2013). Commented Aug 6, 2013 at 18:58
  • For the latest version of Git I'd suggest to read about Git submodules in the official Git documentation. Commented Jan 7, 2015 at 9:54
  • stackoverflow.com/questions/6500524/… Commented Jul 10 at 11:24

3 Answers 3

Reset to default
145

Git has two approaches similar to, but not exactly equivalent to svn:externals:

  • Subtree merges insert the external project's code into a separate sub-directory within your repo. This has a detailed process to set up and then is very easy for other users, because it is automatically included when the repository is checked out or cloned. This can be a convenient way to include a dependency in your project.
    It is easy to pull changes from the other project, but complicated to submit changes back. And if the other project have to merge from your code, the project histories get merged and the two projects effectively become one.

  • Git submodules (manual) link to a particular commit in another project's repository, much like svn:externals with an -r argument. Submodules are easy to set up, but all users have to manage the submodules, which are not automatically included in checkouts (or clones).
    Although it is easy to submit changes back to the other project, doing so may cause problems if the repo has changed. Therefore it is generally not appropriate to submit changes back to a project that is under active development.

Improve this answer
Sign up to request clarification or add additional context in comments.

6 Comments

FYI, it is now possible to specify specific revisions with svn:externals now (since 1.5 or 1.6 I believe?)
FYI, git submodules can be automatically managed and commited. git creates a .gitmodules file that can/should be commited just like the .gitignore file. See [git-scm.com/book/en/Git-Tools-Submodules] for more information.
@NateParsons It has always been possible to specify exact revision numbers with svn:externals. With revision 1.5, the syntax was changed to a more flexible format. What was added was relative URL addressing.
I think it is not possible to git submodule single files like with svn:externals
This sounds like something almost, but not entirely unlike, tea.
|
47

As I mention in "Git submodule new version update", you can achieve the same SVN external feature with Git 1.8.2 submodules:

git config -f .gitmodules submodule.<path>.branch <branch>

This is enough for a submodule to follow a branch (as in the LATEST commit of a remote branch of a submodule upstream repo). All you need to do is a:

git submodule update --remote

That will update the submodule.

More details are in "git submodule tracking latest".

To convert an existing submodule into one tracking a branch: see all the steps in "Git submodules: Specify a branch/tag".

Improve this answer

6 Comments

Can you do partial checkout like with svn:externals?
@nowox Yes, you can have sparse checkout (git 1.7+ stackoverflow.com/a/2372044/6309) associated to submodules (stackoverflow.com/a/17693008/6309)
unfortunately all the sparse checkout related answers never give any example :( I'll try to write a Gist example for this...
There is still an issue with this. You still have to get the whole history of a repository where you only need one small part. In my case is 100kB over 2GB. I can of course use --depth but it doesn't really address the problem.
@nowox It is best to ask a new question explaining exactly what your use case is: I have no idea if your 2GB repo is a submodule, or a main repo with submodule, and what exactly you need to extract from it.
|
11

I'm the author of gil (git links) tool

I have an alternative solution for the problem - gil (git links) tool

It allows to describe and manage complex git repositories dependencies.

Also it provides a solution to the git recursive submodules dependency problem.

Consider you have the following project dependencies: sample git repository dependency graph

Then you can define .gitlinks file with repositories relation description:

# Projects CppBenchmark CppBenchmark https://github.com/chronoxor/CppBenchmark.git master CppCommon CppCommon https://github.com/chronoxor/CppCommon.git master CppLogging CppLogging https://github.com/chronoxor/CppLogging.git master # Modules Catch2 modules/Catch2 https://github.com/catchorg/Catch2.git master cpp-optparse modules/cpp-optparse https://github.com/weisslj/cpp-optparse.git master fmt modules/fmt https://github.com/fmtlib/fmt.git master HdrHistogram modules/HdrHistogram https://github.com/HdrHistogram/HdrHistogram_c.git master zlib modules/zlib https://github.com/madler/zlib.git master # Scripts build scripts/build https://github.com/chronoxor/CppBuildScripts.git master cmake scripts/cmake https://github.com/chronoxor/CppCMakeScripts.git master

Each line describe git link in the following format:

  1. Unique name of the repository
  2. Relative path of the repository (started from the path of .gitlinks file)
  3. Git repository which will be used in git clone command Repository branch to checkout
  4. Empty line or line started with # are not parsed (treated as comment).

Finally you have to update your root sample repository:

# Clone and link all git links dependencies from .gitlinks file gil clone gil link # The same result with a single command gil update

As the result you'll clone all required projects and link them to each other in a proper way.

If you want to commit all changes in some repository with all changes in child linked repositories you can do it with a single command:

gil commit -a -m "Some big update"

Pull, push commands works in a similar way:

gil pull gil push

Gil (git links) tool supports the following commands:

usage: gil command arguments Supported commands: help - show this help context - command will show the current git link context of the current directory clone - clone all repositories that are missed in the current context link - link all repositories that are missed in the current context update - clone and link in a single operation pull - pull all repositories in the current directory push - push all repositories in the current directory commit - commit all repositories in the current directory

More about git recursive submodules dependency problem.

Improve this answer

1 Comment

You should put a disclaimer at the top of the post saying that you're the author of gil.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.