Serving Bazaar with FastCGI
===========================
This document describes one way to set up a Bazaar HTTP smart server,
using Apache 2.0 and FastCGI or mod_python.
For more information on the smart server, and other ways to configure it
see the main `smart server documentation`_.
.. _smart server documentation: #running-a-smart-server
Example
-------
You have a webserver already publishing `/srv/example.com/www/code` as
`http://example.com/code/...` with plain HTTP. It contains bzr branches and
directories like `/srv/example.com/www/code/branch-one` and
`/srv/example.com/www/code/my-repo/branch-two`. You want to provide read-only
smart server access to these directories in addition to the existing HTTP
access.
Configuring Apache 2.0
----------------------
FastCGI
~~~~~~~
First, configure mod_fastcgi, e.g. by adding lines like these to your
httpd.conf::
LoadModule fastcgi_module /usr/lib/apache2/modules/mod_fastcgi.so
FastCgiIpcDir /var/lib/apache2/fastcgi
In our example, we're already serving `/srv/example.com/www/code` at
`http://example.com/code`, so our existing Apache configuration would look
like::
Alias /code /srv/example.com/www/code
<Directory /srv/example.com/www/code>
Options Indexes
# ...
</Directory>
We need to change it to handle all requests for URLs ending in `.bzr/smart`. It
will look like::
Alias /code /srv/example.com/www/code
<Directory /srv/example.com/www/code>
Options Indexes FollowSymLinks
RewriteEngine On
RewriteBase /code
RewriteRule ^(.*/|)\.bzr/smart$ /srv/example.com/scripts/bzr-smart.fcgi
</Directory>
# bzr-smart.fcgi isn't under the DocumentRoot, so Alias it into the URL
# namespace so it can be executed.
Alias /srv/example.com/scripts/bzr-smart.fcgi /srv/example.com/scripts/bzr-smart.fcgi
<Directory /srv/example.com/scripts>
Options ExecCGI
<Files bzr-smart.fcgi>
SetHandler fastcgi-script
</Files>
</Directory>
This instructs Apache to hand requests for any URL ending with `/.bzr/smart`
inside `/code` to a Bazaar smart server via FastCGI.
Refer to the mod_rewrite_ and mod_fastcgi_ documentation for further
information.
.. _mod_rewrite: http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html
.. _mod_fastcgi: http://www.fastcgi.com/mod_fastcgi/docs/mod_fastcgi.html
mod_python
~~~~~~~~~~
First, configure mod_python, e.g. by adding lines like these to your
httpd.conf::
LoadModule python_module /usr/lib/apache2/modules/mod_python.so
Define the rewrite rules with mod_rewrite the same way as for FastCGI, except
change::
RewriteRule ^(.*/|)\.bzr/smart$ /srv/example.com/scripts/bzr-smart.fcgi
to::
RewriteRule ^(.*/|)\.bzr/smart$ /srv/example.com/scripts/bzr-smart.py
Like with mod_fastcgi, we also define how our script is to be handled::
Alias /srv/example.com/scripts/bzr-smart.py /srv/example.com/scripts/bzr-smart.py
<Directory /srv/example.com/scripts>
<Files bzr-smart.py>
PythonPath "sys.path+['/srv/example.com/scripts']"
AddHandler python-program .py
PythonHandler bzr-smart::handler
</Files>
</Directory>
This instructs Apache to hand requests for any URL ending with `/.bzr/smart`
inside `/code` to a Bazaar smart server via mod_python.
NOTE: If you don't have bzrlib in your PATH, you will be need to change the
following line::
PythonPath "sys.path+['/srv/example.com/scripts']"
To::
PythonPath "['/path/to/bzr']+sys.path+['/srv/example.com/scripts']"
Refer to the mod_python_ documentation for further information.
.. _mod_python: http://www.modpython.org/
Configuring Bazaar
------------------
FastCGI
~~~~~~~
We've configured Apache to run the smart server at
`/srv/example.com/scripts/bzr-smart.fcgi`. This is just a simple script we need
to write to configure a smart server, and glue it to the FastCGI gateway.
Here's what it looks like::
import fcgi
from bzrlib.transport.http import wsgi
smart_server_app = wsgi.make_app(
root='/srv/example.com/www/code',
prefix='/code/',
path_var='REQUEST_URI',
readonly=True,
load_plugins=True,
enable_logging=True)
fcgi.WSGIServer(smart_server_app).run()
The `fcgi` module can be found at http://svn.saddi.com/py-lib/trunk/fcgi.py. It
is part of flup_.
.. _flup: http://www.saddi.com/software/flup/
mod_python
~~~~~~~~~~
We've configured Apache to run the smart server at
`/srv/example.com/scripts/bzr-smart.py`. This is just a simple script we need
to write to configure a smart server, and glue it to the mod_python gateway.
Here's what it looks like::
import modpywsgi
from bzrlib.transport.http import wsgi
smart_server_app = wsgi.make_app(
root='/srv/example.com/www/code',
prefix='/code/',
path_var='REQUEST_URI',
readonly=True,
load_plugins=True,
enable_logging=True)
def handler(request):
"""Handle a single request."""
wsgi_server = modpywsgi.WSGIServer(smart_server_app)
return wsgi_server.run(request)
The `modpywsgi` module can be found at
http://dev.pocoo.org/projects/pocoo/browser/pocoo/wrappers/modpy.py. It is
part of pocoo_. You sould make sure you place modpywsgi.py in the same
directory as bzr-smart.py (ie. /srv/example.com/scripts/).
.. _pocoo: http://dev.pocoo.org/projects/pocoo/
Clients
-------
Now you can use `bzr+http://` URLs, e.g.::
bzr log bzr+http://example.com/code/my-branch
Plain HTTP access should continue to work::
bzr log http://example.com/code/my-branch
Advanced configuration
----------------------
Because the Bazaar HTTP smart server is a WSGI application, it can be used with
any 3rd-party WSGI middleware or server that conforms the WSGI standard. The
only requirements are:
* to construct a `SmartWSGIApp`, you need to specify a **root transport** that it
will serve.
* each request's `environ` dict must have a **'bzrlib.relpath'** variable set.
The `make_app` helper used in the example constructs a `SmartWSGIApp` with a
transport based on the `root` path given to it, and calculates the
'bzrlib.relpath` for each request based on the `prefix` and `path_var`
arguments. In the example above, it will take the 'REQUEST_URI' (which is set
by Apache), strip the '/code/' prefix and the '/.bzr/smart' suffix, and set that
as the 'bzrlib.relpath', so that a request for '/code/foo/bar/.bzr/smart' will
result in a 'bzrlib.relpath' of 'foo/bzr'.
It's possible to configure a smart server for a non-local transport, or that
does arbitrary path translations, etc, by constructing a `SmartWSGIApp`
directly. Refer to the docstrings of `bzrlib.transport.http.wsgi` and the `WSGI
standard`_ for further information.
.. _WSGI standard: http://www.python.org/dev/peps/pep-0333/
Pushing over ``bzr+http://``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is possible to allow pushing data over the http smart server. The
easiest way to do this, is to just supply ``readonly=False`` to the
``wsgi.make_app()`` call. But be careful, because the smart protocol does
not contain any Authentication. So if you enable write support, you will
want to restrict access to ``.bzr/smart`` URLs to restrict who can
actually write data on your system. At this time, it is not possible to
allow some people to have read-only access and others to have read-write
access to the same urls. Because at the HTTP layer (which is doing the
Authenticating), everything is just a POST request. However, it would
certainly be possible to have HTTPS require authentication and use a
writable server, and plain HTTP allow read-only access.
..
vim: ft=rst tw=74 et
