Table of Contents

Options for replacing CVS for Horde Development

Decision

We have decided to keep the current history and structure in CVS, and create a new Git repository. Code will be committed to the Git repository as it is cleaned up for PHP 5 and Horde 4.

Introduction to distributed version control systems

• http://betterexplained.com/articles/intro-to-distributed-version-control-illustrated/
• http://www.infoq.com/articles/dvcs-guide

Description

This project is to determine what the next generation of the Horde will use to store and organize source code.
Some initial work has been done with Git and SVN conversions of the current CVS repository.

Requirements

Must-haves

• Offline review of local changes
• Ability to hook into Whups for ticket updates from commit messages
• Stable, mature codebase
• Functional, usable user interface

Nice-to-haves

• Submodule support

Today checking out a Horde app within an existing Horde checkout works fine. This includes making single-commit changes across applications.

* Browseable by Chora

Naturally no matter what we choose Chora support will either be added or will improve. However if it is already supported by Chora all the better.

The Contenders

In alphabetical order...

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Bazaar

Bazaar from Canonical (i.e. the ubuntu company)

• http://bazaar-vcs.org/

Advantages

• Seems to preserve the most metadata per-commit of any SCM listed here

Disadvantages

• Somewhat specific to Launchpad/Ubuntu development process

Well-known users

• Canonical/Ubuntu

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Git

http://git.or.cz/
http://www.opensolaris.org/os/community/tools/scm/git-report-final.txt
http://www.gitcasts.com/git-talk

Setup

#!/usr/bin/env sh

cd /var/www/git/horde/
export CVSROOT=":pserver:cvsread@anoncvs.horde.org:/repository"

FILES="agora
ansel
chora
<SNIP>
whups
wicked"

for FILE in $FILES
do
    echo $FILE": "
    git-cvsimport -C$FILE $FILE
done

Submodules

I added a git submodule for every horde module inside the horde/horde
repository. Now you can do:

git clone git://git.koch.ro/git/horde/horde
cd horde
git submodule init

foreach modules as MODULE // Only those you want to use
  git submodule update $MODULE      // checks out the module

Now there are some more things[1] to think about when actually developing, but
that's one way it could be done.

• http://git.or.cz/gitwiki/GitSubmoduleTutorial
• http://www.kernel.org/pub/software/scm/git/docs/git-submodule.html

Disk space

ls -C -w60
agora      goops      jonah      nag            swoosh
ansel      groupware  juno       nic            trean
chora      hermes     klutz      occam          turba
CVSROOT    horde      kronolith  passwd         ulaform
dimp       hordedoc   luxor      pearweb        update.sh
forwards   hordeweb   merk       presentations  vacation
framework  imp        midas      sam            vilma
genie      incubator  mimp       scry           volos
gitgc.sh   ingo       mnemo      sesha          whups
gollem     jeta       mottle     skeleton       wicked

/var/www/git/horde$ du -hs
928M

Advantages

• Distributed nature allows offline commits and easy branching

Disadvantages

• Does not preserve history across file or directory renames
• Aimed at large-scale codebases with emphasis on features for those users (ie. Linux Kernel)

Well-known users

• Linux Kernel

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Mercurial

Alternative distributed versioning control system.

Advantages

• Distributed nature allows offline commits and easy branching

Disadvantages

• Toolset possibly less mature than other products

Well-known users

• OpenSolaris

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Subversion

• Chuck Hagenbuch has done some work on writing svn post-commit hooks. These likely can be reused for other SCM systems as well.
• Ben Klang has dome some test conversions of the CVS repository to SVN. The repository size is indeed much larger. In addition submodule support (as we use it today) has not been proven to the satisfaction of the developers.

Well-known users

• Asterisk
• KDE

Previous discussion re: migrating Horde to SVN: http://bugs.horde.org/ticket/5284

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People

While all Horde developers are interested in this project's final recommendation the following people have done work toward making a decision on the next SCM to be used for Horde:

• Ben Klang
• Chuck Hagenbuch

Resource Utilization Comparison

Ingo

SCM	Full (Server) Repository Size	Branch Checkout
CVS	51MB	7MB
SVN	31MB	16MB
git*	18MB	18MB

Beatnik

SCM	Full (Server) Repository Size	Branch Checkout
CVS	736KB	700KB
SVN		1.7MB
Mercurial		724KB

• Note that for Git, repo size and checkout size are the same.

Resources

Bazaar Links

• http://www.markshuttleworth.com/archives/125

Git Links

• http://git.or.cz/gitwiki/GitSvnComparsion
• http://git.or.cz/course/svn.html
• http://www.kernel.org/pub/software/scm/git/docs/gitcvs-migration.html
• http://www.kernel.org/pub/software/scm/git/docs/gittutorial.html
• http://www.kernel.org/pub/software/scm/git/docs/gittutorial-2.html
• http://www.kernel.org/pub/software/scm/git/docs/user-manual.html
• http://www.kernel.org/pub/software/scm/git/docs/glossary.html
• http://www.kernel.org/pub/software/scm/git/docs/everyday.html
• http://blog.moertel.com/articles/2007/12/10/how-i-stopped-missing-darcs-and-started-loving-git
• http://hopper.squarespace.com/blog/2008/7/5/converting-mercurial-to-git.html
• http://bergie.iki.fi/blog/feature_branches_in_midgard_development_with_git/
• http://stackoverflow.com/questions/101752/aborting-a-merge-in-git

Mercurial Links

• http://www.selenic.com/mercurial/wiki/
• http://www.linux.com/feature/121157
• http://www.opensolaris.org/os/community/tools/scm/dcm_evaluation_mercurial/
• http://www.selenic.com/mercurial/wiki/index.cgi/HgWebDirStepByStep
• http://www.selenic.com/mercurial/wiki/index.cgi/PublishingRepositories

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