ITK/Git

ITK version tracking and development is hosted by Git.

Official Repository

One may browse the repository online using the Gitweb interface at http://itk.org/gitweb.

Cloning

Clone ITK using the command

$ git clone git://itk.org/ITK.git

If your institution's firewall blocks the Git port for outgoing connections you may see an error similar to:

Initialized empty Git repository in C:/abc/ITK/.git/itk.org[0: 66.194.253.19]:
errno=No such file or directory
fatal: unable to connect a socket (No such file or directory)

In that case, see below.

If you want to run tests, add the --recursive option to download the Testing/Data submodule.

$ git clone --recursive git://itk.org/ITK.git

This requires Git 1.6.5 or higher. If you do not have it, see below.

All further commands work inside the local copy of the repository created by the clone:

$ cd ITK

If you already cloned and want to add the Testing/Data submodule then run

$ git submodule update --init

For ITKApps, use the url

git://itk.org/ITKApps.git

instead.

Updating

If you have made no local commits and simply want to update your clone with the latest changes, run

$ git pull
$ git submodule update

If you know you do not have the Testing/Data submodule checked out then you can skip the submodule update command.

Branches

At the time of this writing the repository has the following branches:

• master: Development (default)
• release: Release maintenance
• nightly-master: Follows master, updated at 01:00 UTC
• hooks: Local commit hooks (place in .git/hooks)
• dashboard: Dashboard script (see below)

Release branches converted from CVS have been artificially merged into master. Actual releases have tags named by the release version number.

After cloning your local repository will be configured to follow the upstream master branch by default. One may create a local branch to track another upstream branch using git checkout:

$ git checkout -b release origin/release

As a shortcut with Git >= 1.6.5 one may choose a branch during the initial clone:

$ git clone -b release git://itk.org/ITK.git ITKRel

Development

We provide here a brief introduction to ITK development with Git. See the Resources page for further information such as Git tutorials.

Introduction

We require all commits in ITK to record valid author/committer name and email information. Use git config to introduce yourself to Git:

$ git config --global user.name "Your Name"
$ git config --global user.email "you@yourdomain.com"

Note that "Your Name" is your real name (e.g. "John Doe", not "jdoe"). While you're at it, optionally enable color output from Git commands:

$ git config --global color.ui auto

If less displays strange characters and no color, your LESS environment variable may already be set. You can override the less options with:

$ git config --global core.pager "less -FXRS"

The --global option stores the configuration settings in ~/.gitconfig in your home directory so that they apply to all repositories.

Hooks

The hooks branch provides local commit hooks to be placed in .git/hooks. It is shared by many public.kitware.com repositories.

See the general hooks information page to set up your local hooks.

Workflow

We've chosen to approximate our previous CVS-based development workflow after the initial move to Git, at least while things get settled. The basic rule is to rebase your work on origin/master before pushing:

git fetch origin
git rebase origin/master

or

git pull --rebase

The server will refuse your push if it contains any merges. Later we will move to a full branchy workflow based on topic branches.

Topic Stage

We provide a "ITK Topic Stage" repository to which developers may publish arbitrary topic branches and request automatic merges.

The topic stage URLs are

• git://itk.org/stage/ITK.git (clone, fetch)
• http://itk.org/stage/ITK.git (clone, fetch, gitweb)
• git@itk.org:stage/ITK.git (push)

See our Topic Stage Workflow documentation for general instructions. (Currently ITK does not have a next branch. Just skip that part of the instructions and merge directly to master.) When accessing the ITK stage, one may optionally substitute "ssh git@itk.org stage ITK ..." for "ssh git@public.kitware.com stage <repo> ..." in the ssh command-line interface.

Stage Usage Summary
Initial Setup:	$ git remote add stage git://itk.org/stage/ITK.git $ git config remote.stage.pushurl git@itk.org:stage/ITK.git
Fetch Staged Topics:	$ git fetch stage --prune
Create Local Topic:	$ git checkout -b topic-name origin/master $ edit files $ git commit
Stage Current Topic:	$ git push stage HEAD
Print Staged Topics:	$ ssh git@itk.org stage ITK print
Merge Staged Topic:	$ ssh git@itk.org stage ITK merge topic-name

Note that the stage implementation is not ITK-specific and is used for other projects too. If the merge attempt conflicts it may print instructions for performing the merge manually. Ignore these instructions; you will not be able to push the merge commit directly. Instead, identify the commit that conflicts with yours, merge it into your topic locally, push the topic to the stage again, and then repeat the merge request.

Publishing

Pushing

Authorized developers may publish work directly to itk.org/ITK.git using Git's SSH protocol. To request access, fill out the Kitware Password form.

See the push instructions for details.

For ITK, configure the push URL:

git config remote.origin.pushurl git@itk.org:ITK.git

For ITKApps, configure the push URL:

git config remote.origin.pushurl git@itk.org:ITKApps.git

Update Hook

The itk.org repository has an update hook. When someone tries to push changes to the repository it checks the commits as documented here.

Testing

Dashboard

The dashboard branch contains a dashboard client helper script. Use these commands to track it:

$ mkdir -p ~/Dashboards/ITKScripts
$ cd ~/Dashboards/ITKScripts
$ git init
$ git remote add -t dashboard origin git://itk.org/ITK.git
$ git pull origin

The itk_common.cmake script contains setup instructions in its top comments. Update the dashboard branch to get the latest version of this script by simply running

$ git pull origin

Contributing Patches

Contributions of bug fixes and features are commonly produced by the community. This section describes a convenient method for managing such contributions.

Generating a Patch

This content is based on Pro Git Book, Chapter 5: Distributed Git

The typical scenario

• You are a user
• Just found a bug
• Figured out how to fix it
• Want to contribute the fix back to the ITK repository

You can safely create your patch with the following sequence

1. Create a branch
2. Commit your changes to it
3. Generate a patch
4. Send the patch via email (or attach it to a report in the bug tracker)

This can be done with the following commands

 git checkout -b   cool_name_for_branch_for_my_bug_fix_here
 git add           name_of_the_file_that_I_changed_to_fix_the_bug
 git commit

and to generate a patch, finally you do

 git format-patch -M origin/master

This will generate a file for each one of the commits that you did in that branch. The files will have extension .patch, and if you look at their content, it will be a plain text with the format of an email that you can send to the maintainers.

NOTE: if you are a brave Linux user, you can also configure git to send email directly with the command "git send-email"

Applying a Patch

This content is based on Pro Git Book, Chapter 5: Distributed Git

We assume here that you got a .patch file from a contributor.

This file may have arrived to you as:

• A file attached to an email, or
• An email, or
• A file attached to a bug tracker report

Save this .patch file to your disk.

Then use the git command

  git  am   filename_of_cool_bug_fix.patch

Verify the patch content with

  git log --pretty-fuller -1 

Build the code in order to verify the correctness of the patch

Finally, push it to the repository where you want to publish the patch.

Troubleshooting

Firewall Blocks Port 9418

Some institutions have firewalls that block Git's native protocol port 9418. Use the "url.<base>.insteadOf" configuration option to map git URLs to http:

$ git config --global url.http://itk.org/.insteadOf git://itk.org/

This tells Git to translate URLs under the hood by replacing prefixes. After running these commands once in your home directory then you can just use the "git://" mentioned elsewhere on this page and git will use the http protocol automagically.

Git Below 1.6.5

To clone ITK using Git 1.6.4 or lower, use the commands

$ git clone git://itk.org/ITK.git
$ cd ITK
$ git submodule init
$ git submodule update

The remote end hung up unexpectedly

If git push fails with

fatal: The remote end hung up unexpectedly

check that you set the pushurl with "git config". See the push instructions.

If you suspect your ssh key may not be configured correctly, see the authentication test instructions.

Tips

Tip: Renaming

Git does not explicitly track renames. The command

$ git mv old new

is equivalent to

$ mv old new
$ git add new
$ git rm old

Neither approach records the rename outright. However, Git's philosophy is "dumb add, smart view". It uses heuristics to detect renames when viewing history after-the-fact. It even works when the content of a renamed file changes slightly.

In order to help Git efficiently detect the rename, it is important to remove the old file and add the new one in one commit, perhaps by using git mv or the above 3-step procedure. If the new file were added in one commit and the old file removed in the next, Git would report this as a copy followed by a removal. It's copy-detection heuristics are more computationally intensive and must be explicitly enabled with the -C option to relevant operations (such as git blame).

Resources

Additional information about Git may be obtained at sites listed here.