Simple Setups
=============

Consider the following simple scenario where we will be serving Bazaar branches
that live on a single server.  Those branches are in the subdirectories of
``/srv/bzr`` (or ``C:\bzr``) and they will all be related to a single project
called "ProjectX".  ProjectX will have a trunk branch and at least one feature
branch.  As we get further, we will consider other scenarios, but this will be
a sufficiently motivating example.

Smart server
------------

The simplest possible setup for providing outside access to the branches on
the server uses Bazaar's built-in smart server tunneled over SSH_ so
that people who can access your server using SSH can have read and write
access to branches on the server.  This setup uses the authentication
mechanisms of SSH including private keys, and the access control mechanisms of
the server's operating system.  In particular, using groups on the server, it
is possible to provide different access privileges to different groups of
developers.

.. _SSH: http://www.openssh.org/

Setup
~~~~~

There is no setup required for this on the server, apart from having Bazaar
installed and SSH access available to your developers.  Using SSH
configuration options it is possible to restrict developers from using
anything *but* Bazaar on the server via SSH, and to limit what part of the
file system they can access.

Client
~~~~~~

Clients can access the branches using URLs with the ``bzr+ssh://`` prefix.  For
example, to get a local copy of the ProjectX trunk, a developer could do::

  $ bzr branch bzr+ssh://server.example.com/srv/bzr/projectx/trunk projectx

If the developers have write access to the ``/srv/bzr/projectx`` directory, then
they can create new branches themselves using::
  
  $ bzr branch bzr+ssh://server.example.com/srv/bzr/projectx/trunk \
  bzr+ssh://server.example.com/srv/bzr/projectx/feature-gui

Of course, if this isn't desired, then developers should not have write access
to the ``/srv/bzr/projectx`` directory.

Further Configuration
~~~~~~~~~~~~~~~~~~~~~

For a project with multiple branches that are all related, it is best to use a
shared repository to hold all of the branches.  To set this up, do::

  $ cd /srv/bzr
  $ bzr init-repo --no-trees projectx

The ``--no-trees`` option saves space by not creating a copy of the working
files on the server's filesystem.  Then, any branch created under
``/srv/bzr/projectx`` (see `Migration <migration.html>`_ for some ways to do
this) will share storage space, which is particularly helpful for branches that
have many revisions in common, such as a project trunk and its feature
branches.

If Bazaar is not installed on the user's path or not specified in the SSH
configuration, then a path can be specified from the client with the
``BZR_REMOTE_PATH`` environment variable.  For example, if the Bazaar executable
is installed in ``/usr/local/bzr-2.0/bin/bzr``, then a developer could use::

  $ BZR_REMOTE_PATH=/usr/local/bzr-2.0/bin/bzr bzr info \
  bzr+ssh://server.example.com/srv/bzr/proectx/trunk

to get information about the trunk branch.  The remote path can also be
specified in Bazaar's configuration files for a particular location.  See
``bzr help configuration`` for more details.

If developers have home directories on the server, they can use ``/~/`` in
URLs to refer to their home directory.  They can also use ``/~username/`` to
refer to the home directory of user ``username``.  For example, if there are two
developers ``alice`` and ``bob``, then Bob could use::

  $ bzr log bzr+ssh://server.example.com/~/fix-1023

to refer to one of his bug fix branches and::

  $ bzr log bzr+ssh://server.example.com/~alice/fix-2047
  
to refer to one of Alice's branches. [#]_

.. [#] The version of Bazaar installed on the server must be at least 2.1.0b1 
       or newer to support ``/~/`` in bzr+ssh URLs.

Using a restricted SSH account to host multiple users and repositories
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Once you have a bzr+ssh setup using a shared repository you may want to share
that repository among a small set of developers.  Using shared SSH access enables
you to complete this task without any complicated setup or ongoing management.

To allow multiple users to access Bazaar over ssh we can allow ssh access to a common
account that only allows users to run a specific command.  Using a single account
simplifies deployment as no permissions management issues exist for the filesystem.
All users are the same user at the server level.  Bazaar labels the commits with
each users details so seperate server accounts are not required.

To enable this configuration we update the ``~/.ssh/authorized_keys`` to include 
command restrictions for connecting users.

In these examples the user will be called ``bzruser``.

The following example shows how a single line is configured::

  command="bzr serve --inet --allow-writes --directory=/srv/bzr",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-rsa AAA...= my bzr key

This command allows the user to access only bzr and disables other SSH use.  Write
access to each repository in the directory ``/srv/bzr`` has been granted with ``--allow-writes``
and can be removed for individual users that should only require read access.  The root of
the directory structure can be altered for each user to allow them to see only a subet
of the repositories available.  The example below assumes two seperate repositories
for Alice and Bob.  This method will not allow you to restrict access to part
of a repository, you may only restrict access to a single part of the directory structure::

  command="bzr serve --inet --allow-writes --directory=/srv/bzr/alice/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-rsa AAA...= Alice's SSH Key
  command="bzr serve --inet --allow-writes --directory=/srv/bzr/bob/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-rsa AAA...= Bob's SSH Key
  command="bzr serve --inet --allow-writes --directory=/srv/bzr/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-rsa AAA...= Repo Manager SSH Key

Alice and Bob have access to their own repository and Repo Manager
has access to the each of their repositories.  Users are not allowed access to any part of 
the system except the directory specified. The bzr+ssh urls are simplified by 
serving using ``bzr serve`` and the ``--directory`` option.

If Alice logs in she uses the following command for her fix-1023 branch::

  $ bzr log bzr+ssh://bzruser@server.example.com/fix-1023

If Repo Manager logs in he uses the following command to access Alice's
fix-1023::

  $ bzr log bzr+ssh://bzruser@server.example.com/alice/fix-1023

