Web-based code browsing
=======================

Browsing the history of a project online is an important part of version
control, since it allows people to easily see what happens in a branch
without having to have a local, up-to-date copy of that branch.  There are a
number of possible choices for browsing Bazaar branches on the web, but we
will cover one of them in particular detail and briefly mention the other
choices where they differ.

Loggerhead
----------

Loggerhead_ is a code browsing interface for Bazaar branches (now used in
Launchpad).  To see an example of Loggerhead in action, browse to
http://bazaar.launchpad.net/~bzr-pqm/bzr/bzr.dev/files which is the loggerhead
view of Bazaar's trunk branch.  Loggerhead runs as a web application on the
server which is accessed over HTTP via a RESTful interface.  It is possible to
run this application on its own dedicated port as
``http://www.example.com:8080`` or to proxy this location behind a separate web
server, for example at ``http://www.example.com/loggerhead/``.  We will discuss
both of these configurations below.

.. _Loggerhead: http://launchpad.net/loggerhead

Requirements
~~~~~~~~~~~~

Loggerhead depends on a number of other Python packages for the various Web
technologies that it builds on.  Some of these must be installed to use
loggerhead, although some of them are optional.  From the loggerhead `README`
file, these are

1) SimpleTAL for templating.
   On Ubuntu, `sudo apt-get install python-simpletal`
   or download from http://www.owlfish.com/software/simpleTAL/download.html
2) simplejson for producing JSON data.
   On Ubuntu, `sudo apt-get install python-simplejson`
   or use `easy_install simplejson`.
3) Paste for the server. (You need version 1.2 or newer of Paste.)
   On Ubuntu, `sudo apt-get install python-paste`
   or use `easy_install Paste`
4) Paste Deploy  (optional, needed when proxying through Apache)
   On Ubuntu, `sudo apt-get install python-pastedeploy`
   or use `easy_install PasteDeploy`
5) flup (optional, needed to use FastCGI, SCGI or AJP)
   On Ubuntu, `sudo apt-get install python-flup`
   or use `easy_install flup`

Although directions for installing these on Ubuntu are given, most other
GNU/Linux distributions should package these dependencies, making installation
easy.  For Windows and Mac OS X, they should all be ``easy_install``-able or at
worst installable from the Python sources.

Built-in Web Server
~~~~~~~~~~~~~~~~~~~

Loggerhead has a built-in web server and when started with the
``serve-branches`` command, that web server is started on a default port
listening on the localhost.  If port 8080 (the default) is accessible on
``www.example.com``, then running

::

  $ serve-branches --host=www.example.com --port=8080 /srv/bzr

will list all of the available branches under that directory on
``http://www.example.com:8080/``, so that the ProjectX trunk could be browsed
at ``http://www.example.com:8080/projectx/trunk``.  Note that loggerhead
provides HTTP access to the underlying Bazaar branches (similar to that
described in `Smart server over HTTP(S)
<other-setups.html#smart-server-over-http-s>`_), so this command should be run
as a user without write privileges in ``/srv/bzr``.  By default, loggerhead
only listens on the localhost, not any external ports, unless specified as
above.

Behind a Proxy
~~~~~~~~~~~~~~

A more common and more safe way to run loggerhead is behind another web server
which will proxy certain requests to the loggerhead server on the localhost.
To do this, you need to have PasteDeploy installed (see `Requirements`_).
Assuming that your server has Apache running, you need to add configuration
such as this to set up the proxy

::

    <Location "/loggerhead/">
        ProxyPass http://127.0.0.1:8080/
        ProxyPassReverse http://127.0.0.1:8080/
    </Location>

If your proxy runs at some path within the server, then the ``serve-branches``
command must be started with the ``--prefix`` option.  For this example, we
could start loggerhead with the command

::

  $ serve-branches --prefix=/loggerhead /srv/bzr

This would allow the trunk branch of ProjectX to be browsed at
``http://www.example.com/loggerhead/projectx/trunk``.

Loggerhead comes with a script allowing it to run as a service on
``init.d`` based Unix systems.  Contributions to do a similar thing on
Windows servers would be welcomed at http://launchpad.net/loggerhead.
  

Other web interfaces
--------------------

There are a number of other web interfaces available for Bazaar branches (see
the list at http://wiki.bazaar.canonical.com/WebInterfaces) and we will just
mention a couple of them here for their advantages in particular situations.

trac+bzr (http://launchpad.net/trac-bzr)
  Trac is a popular web app that integrates a browser for branches, an issue
  tracker and a wiki.  trac+bzr is a trac extension that allows for the
  trac to be used with Bazaar.

webbzr (http://thoughts.enseed.com/webbzr)
  This is a notable solution because it is written in pure PHP for web hosts
  that don't provide a way to run arbitrary Python applications such as Trac
  or Loggerhead.

Redmine (http://redmine.org/)
  Like trac, Redmine is a full project management application using the Ruby
  on Rails framework.  It includes support for Bazaar branches.