Linux Git and Trac Server Integration

Git Installation and Initialization:

Installation:

Red Hat Enterprise/CentOS: Git is included with Workstation and Server installation DVD. RPM package "git" although the version is often a little behind the current release: yum install git
For the current version of Git see RHEL 6 x86_64 or RHEL 7 x86_64 RPMs (yum install git2u-all)
Ubuntu/Debian: sudo apt-get install git
Installs packages: git-doc git-el git-arch git-cvs git-svn git-email git-daemon-run git-gui gitk gitweb

Git is a distributed CM system with user local repositories with the capability for pier to pier repository synchronization. It is often favorable to have an "origin" server with a "master branch" to represent the release baseline. A Git server can be configured for access via ssh or by http. Ssh requires a user system account and gives users complete unrestricted access to the repository while http access can give complete access or limited read only access. This tutorial will outline the configuration of a Linux based Git server accessed by users via ssh.

SSH and HTTP Git server configuration

Git SSH Server:

A Git repository configured for a server will not require a working directory of checked-out code or a staging area as would a developer, thus it will only require a "bare" repository. Users will make git pull/push requests to the server to sync code. The server will be known as the "origin" repository.

The use of ssh to access the repository will require that each user have a system login.
For information on user accounts, see creating a new user system login.

Create Git repository:

Set user identity:
- git config --global user.name "John Doe"
- git config --global user.email john.doe@megacorp.com
This configures user preferences: ~/.gitconfig
```
[user]
        name = John Doe
        email = john.doe@megacorp.com
    
```
Generate Repository:
- mkdir /srv/git/projectx
- cd /srv/git/projectx
- git init --bare --shared=group application1.git

Interface with Git repository:

Use ssh-keygen to set up account keys
git clone ssh://user@hostname:/srv/git/projectx/application1.git

Git User Configuration:

Git client proxy configuration:

git --global http.proxy http://proxy.megacorp.com:80
or
export HTTP_PROXY=proxy.megacorp.com:80

Test: config --get http.proxy

Configure repository:

Make everything group readable and writable: git config core.sharedrepository 1
Make sure that merges can't happen when you push to the repo. You have to do the merges on your local machine, and then push the result:
git config receive.denyNonFastforwards true

Git client: gitk

Red Hat: Note that Red Hat does not have a package for Gitk. The latest version is available from github.com: gitk
wget https://raw.github.com/gitster/git/master/gitk-git/gitk
chmod +x gitk
This application requires Tcl/tk.
Mint/Ubuntu/Debian: apt-get install gitk
May also install dependency tk

Git-web Installation:

Git-web is a Perl cgi web front-end to Git which allows one to view the Git repository.

Git-web Installation:

Red Hat/CentOS: The RPM package gitweb-caching is available from the Extra Packages for Enterprise Linux (EPEL) website and YUM repository
rpm -ivh gitweb-caching-1.6.5.2-8.b1ab8b5.el6.noarch.rpm
Installs to /var/www/gitweb-caching/...
Mint/Ubuntu/Debian: apt-get gitweb
CGI installs to /usr/lib/cgi-bin/gitweb.cgi

Configuration:

Configure git-web by creating the file /etc/gitweb.conf and place all changes to the configuration here. Do not edit the installation configuration.

File: /etc/gitweb.conf

$projectroot = "/srv/git/projectx/git";
$site_name = "cm2.megacorp.com";
#$home_link_str = "http://cm2.megacorp.com/git-caching/"
$home_link_str = "GIT-Web";
# This just makes the description field wider so you can read # it better 
$projects_list_description_width = 100;
# enable blame
$feature{'blame'}{'default'} = [1];
$feature{'patches'}{'default'} = [512];

If this is your command: git ls-remote userx@cm2.megacorp.com:/srv/git/projectx/git/master note that the "project root" is one directory higher.

Apache web server configuration file:

Red Hat: /etc/httpd/conf.d/gitweb-caching.conf
Mint/Ubuntu/Debian: /etc/apache2/conf.d/gitweb

Add the necessary authentication and authorization. See the YoLinux Apache authentication and authorization tutorial

[Potential Pitfall]: If you get the error in your Apache logs:

"... File does not exist: /var/www/gitweb-caching/gitweb.js, referer:. ..."

Download the file from the Git repo: git-1.7.6.1/gitweb/static/gitweb.js

Gitweb Configuration For Multiple Git Repositories:

File: /etc/gitweb.conf

$projectroot = "/srv/git";

...
...

Note:

The project root is just defined at a higher point in the directory tree. This will cover the repositories held in /srv/git/projectx/git and /srv/git/projecty/.git (for example).
Use symbolic links to place all repositories under the same heirarchy if the repositories are scattered throughout the file system.

Trac and the Git plugin:

Trac Installation:

Red Hat EPEL RPM downloads: https://fedoraproject.org/wiki/EPEL
Download the following RPM packages:
- trac
  Requires: python-genshi06
- trac-git-plugin
Note: many of these RPM packages are listed as "x86_64" 64 bit packages but still have 32 bit "i686" dependencies. The "i686" RPM dependencies are available on the RHEL installation DVD.
RPM package trac installs to:
```
/usr/bin/trac-admin
/usr/sbin/tracd
/var/www/cgi-bin/trac.cgi
/var/www/cgi-bin/trac.fcgi
/etc/trac/...
/usr/lib/python2.6/site-packages/Trac-0.12.2-py2.6.egg-info/...
/usr/lib/python2.6/site-packages/trac/...
/usr/lib/python2.6/site-packages/tracopt/...
/usr/share/doc/trac-0.12.2/...
```
Mint/Ubuntu/Debian:
- apt-get install trac
  This will also install the packages: libsvn1 python-genshi python-pygments python-setuptools python-subversion python-tz subversion
- apt-get install trac-git

Trac Configuration:

Location of Trac configuration: mkdir /srv/trac

Initialize the Trac configuration: trac-admin /srv/trac/projectx initenv

Project Name [My Project]> projectx
Database connection string [sqlite:db/trac.db]>

Give yourself admin privileges: trac-admin /srv/trac/midas/ permission add userx TRAC_ADMIN
Allow the web server to own and access Trac: chown -R apache:apache /srv/trac
SELinux:
- chcon -R -t httpd_sys_content_t /usr/share/trac/
- chcon -R -t httpd_sys_content_t /srv/trac/

Trac-git integration: also see the Trac GitPlugin wiki page

mkdir /srv/trac

Trac configuration file: /srv/trac/projectx/conf/trac.ini

[trac]
...
## Best to use Trac with a "bare" and up to date repo.
repository_dir = /srv/git/projectx/git/master
## repository_sync_per_request = (default)
repository_type = git

...

[git]
cached_repository = true
persistent_cache = true
git_bin = /usr/bin/git
split_page_names = false
## length revision sha-sums should be tried to be abbreviated to (must be >= 4 and <= 40); default: 7
shortrev_len = 40
## (0.12.0.3+) minimum length for which hex-strings will be interpreted as commit ids in wiki context
wiki_shortrev_len = 40

[header_logo]
alt = Megacorp ProjectX
height = -1
link = /
src = /images/ProjectX_logo.png
width = -1

[attachment]
max_size = 8388608
render_unsafe_content = false

# place at end of file
[components]
tracext.git.* = enabled

Note:

Change default for logo and attachement max_size (I use 8388608)
Use 40 char Git object IDs. The reason for this is because the Trac ticket reference to a commit must use all 40 characters in order to generate a proper hyperlink to the checked-in code.
Thus specify: shortrev_len = 40
Example:
[d64582ec9bf6e1bee0ee2e7084739be9c552614f]
or
rd64582ec9bf6e1bee0ee2e7084739be9c552614f (prefixed with "r")
This "wiki format" will generate hyperlinks to the Git commit info. Partial Git object IDs will not work.

Trac Configuration For Multiple Git Repositories:

This capability is only available in Trac 0.12 and later.

Trac configuration file: /srv/trac/projectx/conf/trac.ini

[trac]
repository_sync_per_request =
...


[repositories]
projectx.description=Project X
projectx.dir = /srv/git/projectx/git/master
projectx.type = git
projectx.url = ssh://localhost/srv/git/projectx/git/master
projecty.description=Project Y
projecty.dir = /srv/git/projecty/.git
projecty.type = git
projecty.url = ssh://localhost/srv/git/projecty/.git


[git]
cached_repository = false

...

Note:

Use 40 char Git object IDs and the repository identifier assigned when referencing the Git check-in hash code. The repository identifier is required to distinguish which repository to use.
Example:
[d64582ec9bf6e1bee0ee2e7084739be9c552614f/projectx]
or
[changeset:d64582ec9bf6e1bee0ee2e7084739be9c552614f/projectx]
This "wiki format" will generate hyperlinks to the Git commit info. Partial Git object IDs will not work. The "r" prefix also does not seem to work as it does with a single repository.
Set cached_repository = false for a repository with more than 500 commits. Caching seems to bog things down as a repo grows.
A default code tree can be displayed by adding:
```
.alias = projectx
    
```
This will display the projectx code tree when you go to the source browser. The default without this line is to show only the top starting link. This may be omitted to keep the page simple if the page is too cluttered.
The single repository references in the [trac] section are removed:
- Remove repository_dir = /srv/git/projecx/git/master
- Remove repository_type = git
The repositories in a multi-repository configuration are all defined under [repositories] exclusively.

Git post-commit hooks to update Trac:

File: /srv/git/projectx/git/master/hooks/post-commit

#!/bin/sh
REV=$(git rev-parse HEAD)
trac-admin /srv/trac/projectxy changeset added projectx $REV

File: /srv/git/projecty/.git/hooks/post-commit

#!/bin/sh
REV=$(git rev-parse HEAD)
trac-admin /srv/trac/projectxy changeset added projecty $REV

Note:

there is a single Trac instance /srv/trac/projectxy but two Git repositories: projectx and projecty.
These are executable scripts to be executed by Git.

Trac Admin page for defining multiple repositories:

Trac Admin page for defining multiple repositories

Trac - Apache httpd web server integration:

Trac can be run using the stand-alone Trac daemon "tracd". This configuration shows the use of Apache with Trac.

File: /etc/httpd/conf.d/trac.conf
(Red Hat location)

This example performs no authentication:

Alias /trac/ /var/www/cgi-bin/trac.cgi
<LocationMatch /cgi-bin/trac\.f?cgi">
   SetEnv TRAC_ENV_PARENT_DIR "/srv/trac"
</LocationMatch>
<IfModule mod_python.c>
<Location /trac>
    SetHandler mod_python
    PythonInterpreter main_interpreter
    PythonHandler trac.web.modpython_frontend
    PythonOption TracEnvParentDir /srv/trac
</Location>
</IfModule>

Note: The path /var/www/cgi-bin/ is Red Hat specific.

Restart Apache: service httpd restart

For more on Apache authentication see:

YoLinux Apache Authentication

Repository Home Page:

The final touch is to create a homepage for your repositories so that they are easy to find, especially if you are hosting multiple reporitories. The default homepage for most major Linux distributions (Red Hat, Fedora, CentOS, Ubuntu, Debian) is /var/www/html/index.html Create a home page here or create a redirect to the Trac Wiki home page and post links there.

Redirect to the Trac Wiki

   
<META HTTP-EQUIV="Refresh" Content="0; URL=/trac/projectx">

Sample home page:

   
<html>
<head>
<title>Welcome to Project X</title>
</head>
<body>
<h1>Welcome to Project X</h1>

<ul>
<li> <a href="/trac/projectx">Trac Wiki</a> </li>
<li> <a href="/git-caching/">Git-web</a> </li>
<li> <a href="/jenkins">Jenkins</a> </li>
</ul>

</body>
</html>

Now add Continuous Build and Integration. See the YoLinux Jenkins tutorial.

Links:

Git home page
Trac home page
Git Plugin for Trac - Trac-Hacks
YoLinux.com Subversion and Trac tutorial - lots of Trac administration information. Hosting multiple Trac projects, etc.
YoLinux.com Jenkins tutorial - will require the use of the Jenkins "git" plugin.

Books:

	Distributed Version Control with Git [Kindle Edition] Lars Vogel (Author) A practical introduction into the Git version control system.
	Version Control with Git Jon Loeliger (Author) Powerful Tools and Techniques for Collaborative Software Development Step-by-step ways to track, merge, and manage software projects, using Git.
	Pro Git Scott Chacon (Author) Visual explanations of the git concepts and methodology. Step-by-step ways to track, merge, and manage software projects, using Git.
	Defect Tracking Tools Product Comparison Guide: Large Enterprise Edition TiPS-IT Ziff Davis Media Digital PDF Download
	Defect Tracking Tools Product Comparison Guide: Small / Mid Enterprise Edition TiPS-IT Ziff Davis Media Digital PDF Download