Difference between revisions of "ITK/Git"

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One may browse the repository online using the [http://git.wiki.kernel.org/index.php/Gitweb Gitweb] interface at http://itk.org/gitweb.
 
One may browse the repository online using the [http://git.wiki.kernel.org/index.php/Gitweb Gitweb] interface at http://itk.org/gitweb.
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==Quick Start Guide==
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There is a [[ITK/Git/Simple|quick start guide]] to getting up and running with ITK development. This does not go into any of the background, and makes use of simple Git aliases to simplify operations such as staging topic branches and pushing changes to Gerrit for review.
  
 
==Cloning==
 
==Cloning==

Revision as of 14:26, 21 October 2010

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.

Quick Start Guide

There is a quick start guide to getting up and running with ITK development. This does not go into any of the background, and makes use of simple Git aliases to simplify operations such as staging topic branches and pushing changes to Gerrit for review.

Cloning

These instructions assume a command prompt is available with git in the path. See our Git download instructions for help installing Git.

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

ITK development uses a branchy workflow based on topic branches. Currently we use a single master integration branch for development and one release branch for release maintenance.

Workflow

Our collaboration workflow consists of three main steps:

  1. Create Topics: Develop Locally
  2. Share Topics: Code Review with Gerrit
  3. Integrate Topics: Merge using Topic Stage

ITK-Git-Gerrit-Stage-Workflow-A.png

Local Development

We provide here a brief introduction to local ITK development with Git. See the Resources page for further information such as Git tutorials. Configuration for local development described below can quickly be achieved by executing the Utilities/SetupForDevelopment.sh script.

Introduction

These steps are a one-time setup per-user per-machine.

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.

Local Clone

Create a local clone of the repository to get a work tree for local development. See instructions above.

Hooks

This step should be done once for each local clone of the ITK repository. The Utilities/SetupForDevelopment.sh script will install and configure the hooks. If you forget this step instructions will be printed on the first attempt to "git commit".

The hooks branch provides local commit hooks to be placed in .git/hooks. It is shared by many public.kitware.com repositories. To setup or update the Git hooks, run the script

Utilities/DevelopmentSetupScripts/SetupHooks.sh

This script will setup the hooks and configure the KWStyle and uncrustify pre-commit hooks. The KWStyle hook is enabled by default while the uncrustify hook must be enabled manually. See the general hooks information page for details.

Local Commits

Develop locally on a well-named topic branch:

$ git checkout -b my-cool-feature origin/master
$ edit files
$ git add files
$ git commit

Use the editor to enter a descriptive message (leave the message blank to abort the commit). Start with a one-line summary (suitable for use as an email subject line), then leave a blank line, then use free-form paragraph text to describe the change.

Code Review

We use Gerrit Code Review to perform online code reviews. See these pages for details:

Once a change is reviewed and approved in Gerrit, an ITK developer with access to the upstream repository must integrate the change using the ITK Topic Stage, covered in the following.

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

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.

Release Bug Fix

Bug fixes should be developed directly on the latest release for which they are intended. Follow the above Workflow, but when you get to the Local Commits step, start work from the release branch instead:

$ git checkout -b my-bug-fix origin/release
$ edit files
$ git add files
$ git commit

This topic (my-bug-fix) is built on top of the release branch and so it represents the "release+fix" version. From this point forward the topic should be treated like any other change. Contribute it to be merged directly to master. Continue normally to Code Review:

$ git push gerrit HEAD:refs/for/master/my-bug-fix

Once the code review step is done and the fix has been merged to master, post a message to the insight-developers mailing list to ask the release manager to merge the fix to the release branch. Since the work was based on the release branch and the "release+fix" version is already available it is trivial for the release manager to merge without bringing in any other changes from master.

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.

Patches

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

One may send patches to one of our mailing lists:

See our patch instructions for details.

Submodules

In the ITK.git repository, Testing/Data is not really a directory. It is a submodule, meaning that its content does not actually appear in ITK.git, but in the ITKData.git repository. In ITK.git Git stores in the Testing directory an entry called "Data" that refers to a commit from the ITKData repository. Indeed, one can see this using a low-level "git ls-tree" command:

$ git ls-tree -r 9ec7c03d -- Testing/Data
160000 commit bc9550f3215104818f0464fd6ede7c8ea3462aeb  Testing/Data
              ^^^^^^^^

We can view this commit from ITKData.git: http://itk.org/gitweb?p=ITKData.git;a=commitdiff;h=bc9550f3.

This approach allows us to keep the bulky data out of the main repository and version it separately. Every version of ITK throughout history refers to the exact version of ITKData that it needs using this submodule link.

Updating Data

One can think of the Testing/Data entry in ITK's tree kind of like a file that tells Git which version of ITKData.git we want. If we want to change the version of ITKData.git to which we refer from ITK (perhaps because we've created a new commit in ITKData with some updated images), we commit a change to ITK that updates the Testing/Data "file" to refer to the new version.

First, make the changes to ITK needed to use the new data correctly:

$ git checkout -b my-new-test origin/master
$ git submodule update
$ edit files

Then, make the change to Testing/Data and publish it:

$ cd Testing/Data
$ git checkout master
$ git pull --rebase origin master
$ edit data-files
$ git add -- data-files
$ git commit
$ git config remote.origin.pushurl git@itk.org:ITKData.git
$ git push origin master
$ cd ../..

Finally, update ITK to reference the new version of ITKData. Our work tree already has the new version checked out in Testing/Data so we just need to tell Git to include this change in the next commit.

$ git add -- Testing/Data

The commit may also include the files edited above to use the new data:

$ git add -- files
$ git commit

Now publish the ITK commits as you would any other topic.

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

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

Tips and Tricks for using Git and Gerrit can be found here. Feel free to add your own!

Resources

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