EDIT

# Mirroring Trac

The motivation for this article is to describe setting up two identical Trac installations accessing the same database. One is to a [Shibboleth protected setup":http://dev.e-taxonomy.eu/trac. The other refers to the "Trac installation for EDIT developers](http://dev.e-taxonomy.eu/trac.)

The following sections describe the crucial points setting up a Trac mirror.

## Installing Trac

Trac is programmed in python. So, the following packages needs to be in place before installing Trac.

~~~

apt-get install python

apt-get install python-mysqldb

apt-get install libapache2-mod-python

~~~

Furthermore, we need to enable the python module on the Apache server.

~~~

a2enmod mod_python

~~~

Next, the python setuptools are required to setup python.

~~~

apt-get install python-setuptools

~~~

Now, we are prepared to download the same Trac version as installed on the master site (0.10.4). Then, the software has to be extracted to somewhere and has to be installed running the _setup.py_ script.

~~~

wget http://ftp.edgewall.com/pub/trac/trac-0.10.4.tar.gz

tar xvfz trac-0.10.4.tar.gz

cd trac-0.10.4

python setup.py install

~~~

This should install the Trac system to _/usr/share/trac_.

## Installing plugins

Next, the same trac plugins as on the master must be installed on the slave too.

This can be done by simply copying any _.egg_ files from the master site to the directory _/usr/share/trac/plugins/_

Otherwise, the plugins can be downloaded from e.g. [the trac-hacks plugin page":http://trac-hacks.org/wiki/plugin and installed along the instructions on the "Trac wiki](http://trac.edgewall.org/wiki/TracPlugins.)

Further on, the installed plugins must be enabled within the _[[components]_|section of the trac configuration file. (see [#ConfiguringtheTracMirror Configuring the Trac Mirror]]

Currently, the following plugins have to be installed

* graphviz-0.6.9-py2.4.egg

* TracExtendedXmlRpc-0.1-py2.4.egg

* TracWebAdmin-0.1.2dev_r5753-py2.4.egg

* TracNavigationMenu-1.0m-py2.4.egg

* TracXMLRPC-0.1-py2.4.egg

## Installing Macros

Also, the same wiki macros have to be installed on the slave site as on the master.

So, the easiest way is to simply copy these macros from the master site to the directory _/usr/share/trac/wiki-macros/_

Alternatively, macros can be downloaded from [trac-hacks macros page](http://trac-hacks.org/wiki/macro.)

Currently, the following wiki macros have to be installed

* CSV

## Installing others

Further on, the current master site relies on several other packages, which should be installed as well

~~~

apt-get install python-docutils

apt-get install python-clearsilver

apt-get install graphviz

apt-get install python-pydot

apt-get install librsvg2-bin

~~~

## Configuring the Trac Mirror

Since, we like to setup a mirror for the EDIT Developers Wiki, we should get the master's configuration file and copy it into the subdirectory _conf_ of the EDIT project environment within trac (i.e. _/var/www/trac/edit/conf/trac.ini_)

Next, the Trac configuration file needs to be adapted to the mirror's environment. Here are some crucial points to take care off.

 components section::

 Take care to enable any installed plugins or macros here

 graphviz section::

 Create or change the directory given in the variable _cache_dur_

 project section::

 Adapt the url variable and the location of the icon.

 trac section::

 Adapt the database url (_database=postgres://<db_passwd>:<db_userid>@<db_ip>/trac_edit_) and the path to the subversion repository (_repository_dir_). **Attention:** The repository **must** be located at the same path as the master repository. Otherwise, it will not work due to the shared database configuration. Also, it is **not possible** to use *remote repositories*. Thus, a local [[SVNMirroring|Subversion repository mirror]] has to be installed on the mirror site as well.

### Subversion mirror

Please, refer to the [[SVNMirroring|Subversion repository mirror]] article.

### Templates

Additional templates from the EDIT project environment should be copied to _/var/www/trac/edit/templates_.

### htdocs

Additional htdocs from the EDIT project environment should be copied to _/var/www/trac/edit/htdocs_.

## Attachments

Unfortunately, Trac stores any attachment files locally in the _attachment_ subdirectory of the relating project environment (e.g. _/var/www/trac/edit/attachments_). So, they have to be transferred manually to the mirror site.

 **TODO:** Implement a method to synchronise the attachment file regularly. May [rsync](http://rsync.samba.org/) would be a solution to do this. Another idea is to use the subversion repository to store and access the attachments. Perhaps, there will be already an existing plugin doing this job ?

## Enabling Apache

Enabling Trac as an Apache site can be done by providing a site description e.g. like _/etc/apache2/sites-available/trac_ and to enable the site by

~~~

a2ensite trac

~~~

Here is a valid site description for trac with Shibboleth single sign-on. Make sure to adopt the PythonOption _TracEnv_ and _TracUriRoot_ to your needs.

~~~

<Location /trac>

    SetHandler mod_python

    PythonHandler trac.web.modpython_frontend

    PythonOption TracEnv /var/www/trac/edit

    PythonOption TracUriRoot /trac

    AuthType           shibboleth

    ShibRequireSession On

    require            valid-user

</Location>

Alias /_sharedtrac "/usr/share/trac/htdocs"

Alias /trac_htdocs "/var/www/trac/edit/htdocs"

<Directory "/usr/share/trac/htdocs">

    Options Indexes MultiViews

    AllowOverride None

    Order allow,deny

    Allow from all

</Directory>

~~~

Finally, restart apache and hopefully enjoy your trac mirror!