Programming with Subversion, Trac and Buildbot
version 1.1
Date: 8th June, 2006

Olivier Ramonat <>
Pascal Obry <>


1  Introduction

This document attempts to desribe a coherent, simple and secure way to install and administrate a suite of project management tools 12 : These three tools, installed on the same server, can interact together to improve the quality and speed up software development.

2  How to configure your system

2.1  GNU/Linux and MacOS

2.1.1  Create user accounts

Three user accounts have to be created on the server. This must be done by user root with adduser command :

$ adduser svn $ adduser trac $ adduser buildbot

2.2  Cygwin/Windows

Subversion, Trac and Buildbot can be used on Windows 2000/XP thanks to Cygwin environment 5.

2.2.1  Install Cygwin

Installing Cygwin is fast and easy :

2.2.2  Create user accounts

Create users svn, trac, buildbot with the standard Windows interface. Create the files `/etc/passwd' and `/etc/group' from Cygwin command line with :

$ mkpasswd -l > /etc/passwd $ mkgroup -l > /etc/group

2.2.3  Configure SSH

This step will allow to remotely connect in a secure way to the Windows computer. It will be used later to connect to the subversion repository.

$ ssh-host-config

To the questions answer :

2.2.4  Install Trac

Installing Trac is more complex. Cygwin does not provide a binary package and Trac has several dependencies. Before building Clearsilver, be sure that the Cygwin compiler first appear in your PATH.

2.2.5  Install Buildbot

Cygwin does not provide a package for Buildbot. However the installation is simple and well describe in the INSTALL file provided by Buildbot : Before building Twisted and Buildbot, be sure that the Cygwin GCC/C compiler first appears in your PATH.

2.2.6  Run as Windows services

The next step is to run Trac and Buildbot as Windows services to automatically launched them at system start.

First, add c:\cygwin\bin to the system PATH via the Windows standard interface. You need to create a CYGWIN variable with a value of "tty ntsec".

Then use Cygwin cygrunsrv tool to create the services. This must be done after the installation of Trac and Buildbot as described in this document.

$ cygrunsrv -I buildbot -c /home/buildbot/buildroot -a "--no_save -y buildbot.tac" -e CYGWIN="tty ntsec" -p /usr/bin/twistd -u buildbot -w buildbot_pwd

Start the service :

$ cygrunsrv --start buildbot

Obtain a description of all parameters :

$ cygrunsrv --help

2.2.7  Final note

Installation of free tools, developed mainly for GNU/Linux, under Windows with Cygwin is possible and quite simple. However, some adjustments can be necessary according to the computer configuration.

This section main goal is to guide the administrator in his installation by describing the process of a Cygwin installation.

All the following sections are platforms independent.

3  Configure Subversion

All the following commands will be executed by user svn

3.1  Create a Subversion repository

Create the repository my_proj :

$ svnadmin create --fs-type=fsfs my_proj

Subversion provide two ways to store its database : Prefer FSFS which is more stable in case of Subversion crash.

3.2  Access to the repository via svn+ssh

All project's users must have a system account and the ability to SSH into the server machine.

To automate connection using scripts, create an RSA key without pass-phrase and use it to authenticate on the server.

Create a local RSA key :

$ ssh-keygen -t rsa

Copy the public key to server_addr :

$ ssh-copy-id -i /home/user/.ssh/ user@server_addr

On Cygwin ssh-copy-id doesn't exist. You'll have to manually add the key `/home/user/.ssh/' into user@server_addr:.ssh/authorized_keys.

Then check out project sources my_proj :

$ svn co svn+ssh://user@server_addr/home/svn/my_proj

You do not need to enter your pass-phrase. The connection is automatic and controlled by the SSH RSA key.

3.3  Hook Subversion

Subversion automatically executes the scripts that are placed in the repository's `hooks' directory.

3.3.1  pre-commit hook

The script hooks/pre-commit is executed before a commit. Some conditions can be checked on the committed files. For example, it is possible to test if the files follows the coding guidelines or to check for a valid syntax (if performed by the compiler6).

It is possible to prevent SVN check-in unless an *open* Trac ticket number is specified in log message. This cooperation between Trac and Subversion ensures proper tracing of all activities on the repository. Tracing is one of the most important point that leads to software quality.

3.3.2  post-commit hook

The hooks/post-commit script is often used to send mail notifications. It can also be used to record the commit log message into the corresponding Trac ticket (section 4.3) or to execute automatic compilations with Buildbot(section 5.1.4).

In the following sections, it is supposed that Subversion repository uses a standard structure :

my_proj | | - trunk | | - branches | | | | - release_1 | | - release_2

4  Trac

All the operations will be done by user trac

4.1  Create a Trac project

The creation of the project my_proj under Trac is done by the tool trac-admin.

Project creation under `/home/trac/rootenv' :

$ trac-admin rootenv/my_proj initenv Project Name [My Project]> My Project Database connection string [sqlite:db/trac.db]> Path to repository [/var/svn/test]> /home/svn/my_proj Templates directory [/opt/local/share/trac/templates]>

You only need to name the project and to point to the Subversion repository (on the same server).

4.2  Launch Trac

Trac is launched by :

$ tracd -a *,users.htdigest,TracRealm -p 8000 -e /home/trac/rootenv/

Where users.htdigest is created by :

$ htdigest -c users.htdigest TracRealm user

Force Trac authentication to have proper tracing of the activities.

The Trac server is running on my_server on port 8000. It can be accessed at URL : http://my_server:8000

4.3  From Subversion to Trac tickets

A Trac ticket can be a bug report or a feature request. Trac assigns automatically a number to each ticket.

Use a Subversion hook to link the Subversion transaction to the Trac ticket.

The scripts/trac-post-commit-hook python script looks for the string refs #11, #12 or fixes #14 in Subversion log and adds the transaction log into Trac ticket history.

When a log contains fixes the ticket is automatically marked as closed.

The `trac-pre-commit-hook' can reject all transactions that do not refer to a ticket number.

5  Automate with Buildbot

5.1  Configure Buildbot

5.1.1  Requirement

Fetch TwistedSumo archive then install : On Debian :
$ apt-get install python-twisted python-twisted-web

Get buildbot and install it.

Buildbot tested version, Buildbot-0.7.3, does not allow multiple projects on a server. If you want to use multiple projects you have to override a class in master.cfg, (see section 5.1.5). But there are some limitations as it will not be possible to create a page per project.

This feature is expected to be better integrated in future Buildbot versions.

5.1.2  Configure Buildbot server

As buildbot user, run :

$ mkdir /home/buildbot/buildroot $ buildbot master /home/buildbot/buildroot $ cd /home/buildbot/buildroot $ cp Makefile.sample makefile

Get master.cfg and edit it according to your configuration.

Define the connection parameters :
all Buildbot clients must have access to svnserver.

svnserver = 'svn+ssh://buildbot@my_server/home/svn/' port = 9989 # for slaves wport = 8010 # for web interface

Declare Buildbot client :
Set a login/password to each buildbot client. Here bot1 and bot2 :

# bot-machines used for the builds c['bots'] = [("bot1", "bot_passwd"), ("bot2", "bot_passwd")]

Project configuration :
Compile each time a change is committed :
Use RepositoryScheduler instead of Scheduler : a parameter repository is defined to allow multiple projects (see 5.1.5).

s_trunk=RepositoryScheduler(name="trunk-only", branch="trunk", treeStableTimer=1*60, builderNames=["test-linux", "test-windows"], repository='/home/svn/test') s_b1=RepositoryScheduler(name="release-1", branch="branches/release-1", treeStableTimer=1*60, builderNames=["test-linux", "test-windows"], repository='/home/svn/test') c['schedulers'].append (s_trunk) c['schedulers'].append (s_b1)

This forces a rebuild each time a change is committed on Subversion. Buildbot waits for the tree to become stable before initiating a build (using timeout treeStableTimer).

Note that Buildbot pays attention to branches. The above example has been define to only consider the trunk and branches/release-1.

Commands to run :
If your project url is baseURL, compilation process is done by make build and tests run by make test, you have to write :

test_steps = [s(step.SVN, mode="update", baseURL=svnserver + 'test/'), s(step.Configure), s(step.Compile), s(step.Test, command=["make", "check"])] test_f = factory.BuildFactory(test_steps)

Define the builders :
The project test has two slaves bot1 and bot2. They appear as test-linux and test-windows in Buildbot web interface.

bot1_builder = {'name': "test-linux", 'slavename': "bot1", 'builddir': "test-linux", 'factory': test_f, } bot2_builder = {'name': "test-windows", 'slavename': "bot2", 'builddir': "test-windows", 'factory': test_f, } c['builders'].append (bot1_builder) c['builders'].append (bot2_builder)

Daily tests :
A build is triggered every day at 11h45 PM.

test_nightly=Nightly('test-nightly', ['test-linux'], hour=23, minute=45, branch='trunk') c['schedulers'].append (test_nightly)

Notification :
A notification of builder events will be sent to admin@my\_server.

c['status'].append(mail.MailNotifier (builders=['test-linux', 'test-windows'], fromaddr="buildbot@my_server", extraRecipients=["admin@my_server"])

Launch the server :
$ make start

5.1.3  Create a Buildbot slave

Module python-twisted-web is not required for Buildbot slave.

$ buildbot slave buildroot server_addr:9989 <name> <passwd>

Where server_addr is the server address, default port is 9989. Slave login/password is set in server configuration.

WARNING : Buildbot slave must be able to SSH into the server automatically (use an RSA key as described in section 3.2 page ??).

5.1.4  From Subversion to Buildbot

scripts/trac-post-commit-hook python script must be called in hooks/post-commit to notify Buildbot server that a change has been committed in Subversion.

5.1.5  Multiples projects

Create a new class RepositoryScheduler that overrides Buildbot Scheduler.

When Buildbot receives a notification from the Subversion hook, it will only rebuild the corresponding project.

class RepositoryScheduler(Scheduler): """Extend Scheduler to allow multiple projects""" def __init__(self, name, branch, treeStableTimer, builderNames, repository, fileIsImportant=None): """ Override Scheduler.__init__ Add a new parameter : repository """ Scheduler.__init__(self, name, branch, treeStableTimer, builderNames, fileIsImportant) self.repository = repository def addChange(self, change): """Call Scheduler.addChange only if the repository is modified""" # check to make sure the repository matches! cs = change.comments.split(' ') if len(cs) > 0: repo = cs[0] log.msg('checking %s vs %s' % (repo, self.repository)) if repo != self.repository: log.msg("%s ignoring repository %s" % (self, repo)) return # call our parent since this on the correct repository Scheduler.addChange(self, change)

6  Appendix

6.1  Subversion hooks

scripts/ script contains functions for pre-commit and post-commit hooks.

6.1.1  pre-commit

Function check_style
checks style and syntax of modified files. Uses Style_Checker (

Function log_not_empty
checks if log is not empty.

Function trac_pre_commit_record_log
checks if a log message contains a reference to a Trac ticket number. Uses scripts/trac-pre-commit-hook.

6.1.2  post-commit

Function trac_post_commit_record_log
appends Subversion log to Trac ticket history. Uses scripts/trac-post-commit-hook.

Function send_mail_post_commit
sends a mail at each commit.

Function buildbot_post_commit
sends a notification to Buildbot server. Usesscripts/

6.1.3  Examples

Two hooks scripts are provided :

6.2  Buildbot

You can find an example of Buildbot server configuration here : scripts/buildbot/master.cgf.
Tested on GNU/Linux and MacOs
Tested on Windows/Cygwin, discussed after in this document
Subversion is version control system, the quasi-official replacement for CVS, used by Python, Apache, GCC or KDE for example
Trac is a Sourceforge like
a POSIX emulation layer for Windows
As the -gnatc GNAT's option for example

This document was translated from LATEX by HEVEA.