Braid is a simple tool to help track vendor branches in a Git repository.

The project homepage is here.

Vendoring allows you take the source code of an external library and ensure it's version controlled along with the main project. This is in contrast to including a reference to a packaged version of an external library that is available in a binary artifact repository such as Maven Central, RubyGems or NPM.

Vendoring is useful when you need to patch or customize the external libraries or the external library is expected to co-evolve with the main project. The developer can make changes to the main project and patch the library in a single commit.

The problem arises when the external library makes changes that you want to integrate into your local vendored version or the developer makes changes to the local version that they want integrated into the external library.

A typical "implementation" of vendoring is to simply download or checkout the source for the external library, remove the .git or .svn directories and commit it to the main source tree. However this approach makes it very difficult to update the library. When you want to update the library do you re-apply your local changes onto a new copy of the vendored library or do you re-apply the changes from the external library to local version? Both cases involve manual generation and application of patch files to source trees.

This is where Braid comes into play. Braid makes it easy to vendor in remote git repositories and use an automated mechanism for updating the external library and generating patches to upgrade the external library.

Braid creates a file .braids in the root of your repository that contains references to external libraries or mirrors. There are two types of mirrors in Braid: squashed and full. Mirrors are squashed by default, which is what you'll generally want because they're faster and don't pollute your history with commits from the mirrors.

Full mirrors are useful when you want to view imported history in your own project. You usually want this if the mirror is also a repository you have access to, for example, when using shared code across projects.

Please note that you cannot change between mirror types after the initial add. You'll have to remove the mirror and add it again.

gem install braid

Let's assume we're writing the project myproject that needs grit in lib/grit. Initialize the repo (nothing braid related here):

git init myproject
cd myproject
touch README
git add README
git commit -m "initial commit"

Now let's vendor grit:

braid add git://github.com/mojombo/grit.git lib/grit

And you're done! Braid vendored grit into lib/grit. Feel free to inspect the changes with git log or git show.

If further down the line, you want to bring new changes from grit into your repository, just update the mirror:

braid update lib/grit

If you make changes to the grit library and want to generate a patch file so that you can submit the patch file to the grit project:

braid diff lib/grit > grit.patch

Once those changes have been applied to grit you probably want to update your local version of grit again.

braid update lib/grit

Use the built in help system to find out about all commands and options:

braid help
braid help add # or braid add --help

braid add git://github.com/rails/rails.git vendor/rails

braid add --revision bf1b1e0 git://github.com/rails/rails.git vendor/rails

braid add --full git://github.com/mislav/will_paginate.git vendor/plugins/will_paginate

# Update a specific mirror
braid update vendor/plugins/cache_fu
# Update all mirrors
braid update

If a braid update creates a conflict, braid will stop execution and leave the partially committed files in your working copy, just like a normal git merge conflict would.

You will then have to resolve all conflicts and manually run git commit. The commit message is already prepared.

If you want to cancel the braid update and the merge, you'll have to reset your working copy and index with git reset --hard.

braid update --revision 6c1c16b vendor/rails
braid update --head vendor/rails

braid diff vendor/rails

We appreciate any patches, error reports and usage ideas you may have. Please submit an issue or pull request on GitHub.

While preparing to release Braid v1.0 the support for subversion repositories was removed as there was no active maintainers and inadequate test coverage. If there is anyone motivated to re-add and maintain the Subversion support, please contact the authors.

This tool is a downstream evolution of a identically named tool initially developed by Cristi Balan (evilchelu) and Norbert Crombach (norbert). All credit goes to the original for the initial code and idea. Further maintenance and bugs are courtesy of Peter Donald.

• Cristi Balan
• Norbert Crombach
• Peter Donald

• Alan Harper
• Christoph Sturm
• Dennis Muhlestein
• Ferdinand Svehla
• Michael Klishin
• Roman Heinrich
• Travis Tilley
• Tyler Rick