VTK/Git

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VTK version tracking and development is hosted by Git.

Official Repository

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

Cloning

One may clone the repository using git clone through the native git protocol: 

$ git clone git://vtk.org/VTK.git VTK

or through the (less efficient) http protocol: 

$ git clone http://vtk.org/VTK.git VTK

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

$ cd VTK

For VTKData the URLs are 

git://vtk.org/VTKData.git
http://vtk.org/VTKData.git

Branches

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

  • master: Development (default)
  • hooks: Local commit hooks (place in .git/hooks)

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

Development

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

Introduction

We require all commits in VTK 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

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.

We already provide support for topic branches and merges through the VTK Topic Stage described in the next section.

Topic Stage

We provide a "VTK 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 VTK does not have a next branch. Just skip that part of the instructions and merge directly to master.) When accessing the VTK stage, one may optionally substitute "ssh git@vtk.org stage VTK ..." for "ssh git@public.kitware.com stage <repo> ..." in the ssh command-line interface.

Stage Usage Summary

Initial Setup: 

$ git remote add stage git://vtk.org/stage/VTK.git
$ git config remote.stage.pushurl git@vtk.org:stage/VTK.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@vtk.org stage VTK print

Merge Staged Topic: 

$ ssh git@vtk.org stage VTK merge topic-name

Note that the stage implementation is not VTK-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

Authorized developers may publish work directly to vtk.org/VTK.git using Git's SSH protocol.

Note that we may not grant all contributors push access to the vtk.org repository. The distributed nature of Git allows contributors to retain authorship credit even if they do not publish changes directly.

If you are an external contributor without push access, you can submit a patch to the vtk-developers mailing list, see #Submitting_a_patch.

Authentication

All publishers share the git@vtk.org account but each uses a unique ssh key for authentication. If you do not have a public/private ssh key pair, generate one: 

$ ssh-keygen -C 'you@yourdomain.com'
Generating public/private rsa key pair.
Enter file in which to save the key ($HOME/.ssh/id_rsa):
Enter passphrase (empty for no passphrase): (use-a-passphrase!!)
Enter same passphrase again: (use-same-passphrase!!)
Your identification has been saved in $HOME/.ssh/id_rsa.
Your public key has been saved in $HOME/.ssh/id_rsa.pub.

To request access, fill out the Kitware Password form. Include your ssh public key, id_rsa.pub, and a reference to someone our administrators may contact to verify your privileges.

Generating an ssh key on Windows

If you are familiar with generating an ssh key on Linux or Mac, you can follow the same procedure on Windows in a "Git Bash" prompt. There is an ssh-keygen program installed with msysGit to help you set up an ssh identity on a Windows machine. By default it puts the ".ssh" directory in the HOME directory, which is typically "/c/Users/Username" on Vista and Windows 7; on XP, it's "/c/Documents and Settings/Username".

Alternatively, you can also set up a "normal" Windows command prompt shell such that it will work with msysGit, without ever invoking the Git Bash prompt if you like. If you install msysGit and accept all its default options, "git" will not be in the PATH. However, if you add "C:\Program Files (x86)\Git\cmd" to your PATH, then only the two commands git and gitk are available to use via *.cmd script wrappers installed by msysGit. Or, if you add "C:\Program Files (x86)\Git\bin" to your PATH, then all of the command line tools that git installs are available.

The full PuTTY suite of tools includes an application called PuTTYgen. If you already have a private key created with PuTTYgen, you may export it to an OpenSSH identity file. Open the key using PuTTYgen and choose "Conversions > Export OpenSSH key" from the menu bar. That will allow you to save an "id_rsa" file for use in the ".ssh" directory. You can also copy and paste the public key portion of the key from the PuTTYgen text field to save into an "id_rsa.pub" file if you like. Or email it to whoever needs the public side of your key pair.

If you routinely set up your own command prompt environment on Windows, using msysGit from that envrionment is a cinch: just add the full path to either Git\cmd or Git\bin to your PATH. (Or, write your own git.cmd wrapper that is in your PATH that simply calls the git.cmd installed with msysGit.) And make sure you have a HOME environment variable that points to the place where the .ssh directory is.

Pushing

Git automatically configures a new clone to refer to its origin through a remote called origin. Initially one may fetch or pull changes from origin, but may not push changes to it.

In order to publish new commits in the vtk.org repository, developers must configure a push URL for the origin. Use git config to specify an ssh-protocol URL: 

$ git config remote.origin.pushurl git@vtk.org:VTK.git

(Note that 'pushurl' requires Git >= 1.6.4. Use just 'url' for Git < 1.6.4.)

Failing to do so with result in the following error message: "fatal: The remote end hung up unexpectedly".

Once your push URL is configured and your key is installed for git@vtk.org then you can try pushing changes.

For VTKData, the push URL is 

git@vtk.org:VTKData.git

Update Hook

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

Patches

Submitting a patch

If you are an external contributor without push access, you can submit a patch to the vtk-developers mailing list.

  1. subscribe to the vtk-developers mailing list: http://www.vtk.org/mailman/listinfo/vtk-developers
  2. prepare your patch:
# 1. pull from the central repository with rebase, not merge
$ cd VTK
$ git pull --rebase

# 2. create the patch
$ git format-patch

3. send the patch to the vtk-developers list

A contributor with push access will be able to apply the patch and push it to the central repository. See the following section to apply a patch #Applying_a_patch .

ref: Everyday GIT: Individual Developer (Participant)

Applying a patch

When you receive a patch by email, you can apply it locally with: 

$ cd VTK
$ git am -3 -i -s -u patch.txt

If the following error happens: 

Patch format detection failed.

It means the patch was not generated with git format-patch but with git show

To apply a patch generated with git show, use 

$ cd VTK
$ git apply --whitespace=fix patch.txt

Now you have applied the patch, you can review it and test it.

If you are a contributor with push access, you can decide to reject or accept the patch and maybe apply additional commits. At this point, you are ready to publish the patch to the central repository #Publishing .

ref: Everyday GIT: Integrator

Troubleshooting

fatal: The remote end hung up unexpectedly

  • If git push fails with "fatal: The remote end hung up unexpectedly", you probably forgot to set the push url with "git config" see #Pushing.

Restoring files locally

Q: "I cloned the VTK repository. Now I "rm -rf Hybrid". How do I get it back?"
A: git checkout Hybrid
Q: "I modified a file locally. I want to revert it."
A: git checkout myfile.cxx

Resources

Additional information about Git may be obtained at these sites:

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