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Centralized Workflow Tutorial
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=============================
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This document describes a possible workflow for using Bazaar_. That of
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using Bazaar_, the distributed version control system, in a centralized
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manner. Bazaar_ is designed to be very flexible and allows several
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different workflows, from fully decentralized to mostly centralized. The
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workflow used here is meant to ease a new user into more advanced usage of
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Bazaar_, and allow them to work in a mix of centralized and decentralized
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In general, this document is meant for users coming from a background of
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centralized version control systems such as CVS or subversion. It is
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common in work settings to have a single central server hosting the
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codebase, with several people working on this codebase, keeping their work
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in sync. This workflow is also applicable to a single developer working
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on several different machines.
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.. _Bazaar: http://bazaar.canonical.com
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This document describes some basic workflow for using Bazaar_. This doesn't
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try to explain *why* every step is done, but more gives recommendations
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about what is considered a good way to work with Bazaar_.
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Bazaar_ is designed to be very flexible in workflows, from fully
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decentralized to mostly centralized.
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The practices here are meant to help ease the user into more advanced usage
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of Bazaar_, and allowing them to work in a mix of centralized and
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decentralized operation.
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In general, this document is meant for people in a work setting. Where
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several people are working on the same codebase, and want to work with
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eachother and keep in sync. However, this workflow is also applicable to a
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single developer, who might work on several machines, and wants to keep in
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.. _Bazaar: http://bazaar-vcs.org
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Bazaar_ branches generally copy the history information around with them,
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which is part of how you can work in a fully decentralized manner. As an
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optimization, it is possible for related branches to combine their storage
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needs so that you do not need to copy around all of this history
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information whenever you create a new branch.
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The best way to do this is to create a `Shared Repository`_. In
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general, branches will share their storage if they exist in a
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subdirectory of a `Shared Repository`_. So let's set up a `Shared
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Repository`_ in our home directory, thus all branches we create
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underneath will share their history storage.
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optimization, it is possible for branches to combine their storage needs,
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so that you do not need to copy around all of this history information
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whenever you create a new branch.
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The best way to do this is to create a `Shared Repository`_. In general,
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branches will share their storage if they exist in a subdirectory of a
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`Shared Repository`_. So lets setup a `Shared Repository`_ in our home
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directory, thus all branches we create underneath will share their history
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% bzr init-repo --trees ~
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Setting up a remote Repository
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---------------------------------
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Many times you want a location where data is stored separately from where
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you do your work. This workflow is required by centralized systems
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(CVS/SVN). Usually they are on separate machines, but not always. This is
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actually a pretty good setup, especially in a work environment. Since it
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ensures a central location where data can be backed up, and means that if
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something happens to a developer's machine, no committed work has to be
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So let's set up a shared location for our project on a remote machine
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called ``centralhost``. Again, we will use a
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`Shared Repository`_ to optimize disk usage.
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% bzr init-repo --no-trees bzr+ssh://centralhost/srv/bzr/
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------------------------------
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Many times you want a location where data is stored separate from where
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you do your work. This workflow is required by centralized systems (CVS/SVN).
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Usually they are on separate machines, but not always. This is actually a
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pretty good setup, especially in a work environment. Because it ensures
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a central location where data can be backed up, and means that if something
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happens to a developer's machine, no committed work has been lost.
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So lets set up a shared location for our project. Again, we will use a
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`Shared Repository`_ to optimize disk usage.::
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% bzr init-repo --no-trees sftp://centralhost/srv/bzr/
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You can think of this step as similar to setting up a new cvsroot, or
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subversion repository. The ``--no-trees`` option tells bzr to not
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populate the directory with a working tree. This is appropriate,
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since no one will be making changes directly in the branches within
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the central repository.
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Here we're using a ``bzr+ssh`` URL, which means to use Bazaar's own
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protocol on top of the SSH secure shell. See the Administrator Guide for
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information about setting up a bzr+ssh server.
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Migrating an existing project to Bazaar
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subversion repository (only obviously it is a little bit simpler).
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Starting to version an existing project
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=======================================
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Now that we have a repository, let's create a versioned project. Most of
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the time, you will already have some code that you are working with,
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Now that we have a repository, lets get going with a new project. Most of
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the time, you will already have some code that you started working with,
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that you now want to version using Bazaar_. If the code was originally
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in source control, there are many ways to convert the project to Bazaar_
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without losing any history. However, this is outside the scope of this
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document. See `Tracking Upstream`_ for some possibilities (section
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"Converting and keeping history").
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.. _Tracking Upstream: http://wiki.bazaar.canonical.com/TrackingUpstream
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XXX: We really need a different document for discussing conversion of a
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project. Right now TrackingUpstream is the best we have, though.
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without losing any history. However, this is outside of the scope of this
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document. See XXXReferenceConversionOfHistory_.
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Developer 1: Creating the first revision
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----------------------------------------
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So first, we want to create a branch in our remote Repository, where we
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want to host the project. Let's assume we have a project named
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"sigil" that we want to put under version control.
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% bzr init bzr+ssh://centralhost/srv/bzr/sigil
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will want to host the project. Let's assume we have a project named
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"sigil" that we want to start versioning, and create an empty branch::
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% bzr init sftp://centralhost/srv/bzr/sigil
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This can be thought of as the "HEAD" branch in CVS terms, or as the "trunk"
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in Subversion terms. We will call this the ``dev`` branch.
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in Subversion terms. We typically call this the ``dev`` branch.
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I prefer working in a subdirectory of my home directory to avoid collisions with all
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the other files that end up there. Also, we will want a project
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I prefer working in a subdirectory of ``$HOME`` to avoid collisions with all
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the other stuff that ends up in ``$HOME``. Also, we will want a project
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directory where we can hold all of the different branches we end up
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% bzr checkout bzr+ssh://centralhost/srv/bzr/sigil dev
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% bzr checkout sftp://centralhost/srv/bzr/sigil dev
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% cp -ar ~/sigil/* .
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% bzr commit -m "Initial import of Sigil"
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In the previous section, we created an empty branch (the ``/sigil``
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branch) on ``centralhost``, and then checkout out this empty branch
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onto our workstation to add files from our existing project. There
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are many ways to set up your working directory, but the steps above
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make it easy to handle working with feature/bugfix branches. And one
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There are many ways to setup your working directory, but the above way
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will makes it easy to handle working with feature/bugfix branches. And one
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of the strong points of Bazaar_ is how well it works with branches.
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At this point, because you have a 'checkout' of the remote branch, any
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commits you make in ``~/work/sigil/dev/`` will automatically be saved
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both locally, and on ``centralhost``.
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commits you make in ``dev/`` will automatically be saved both locally,
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and on ``centralhost``.
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Developer N: Getting a working copy of the project
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--------------------------------------------------
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Since the first developer did all of the work of creating the project,
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all other developers would just checkout that branch. **They should
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still follow** `Setting User Email`_ and `Setting up a local Repository`_.
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all other developers can just get a checkout of that branch. They should
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still follow `Setting User Email`_ and `Setting up a local Repository`_.
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To get a copy of the current development tree::
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Then to get a copy of the current tip::
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% cd ~/work/sigil
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% bzr checkout bzr+ssh://centralhost/srv/bzr/sigil dev
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% bzr checkout sftp://centralhost/srv/bzr/sigil dev
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Now that two people both have a checkout of
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``bzr+ssh://centralhost/srv/bzr/sigil``, there will be times when one of
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the checkouts will be out of date with the current version.
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At commit time, Bazaar_ will inform the user of this and prevent them from
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committing. To get up to date, use ``bzr update`` to update the
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tree with the remote changes. This may require resolving conflicts if the
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same files have been modified.
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``sftp://centralhost/srv/bzr/sigil``, there will be times when one of
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them is out of date with the current version. Bazaar_ will inform the user
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of this and prevent them from committing. To get up to date use ``bzr
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update``, which will update the tree with the remote changes. This may
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require resolving conflicts, in the case that the same files have been
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Developing on separate branches
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===============================
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So far everyone is working and committing their changes into the same
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branch. This means that everyone needs to update fairly regularly and
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branch. Which means that everyone needs to update fairly regularly, and
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deal with other people's changes. Also, if one person commits something
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that breaks the codebase, then upon syncing, everyone will get the
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which breaks the codebase, then everyone has to deal with it.
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Usually, it is better to do development on different branches, and then
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Usually, it is better to do development on individual branches, and then
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integrate those back into the main branch, once they are stable. This is
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one of the biggest changes from working with CVS/SVN. They both allow you
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to work on separate branches, but their merging algorithms are fairly
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weak, so it is difficult to keep things synchronized. Bazaar_ tracks
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weak, so it is difficult to keep things synchronized. Bazaar_ merges track
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what has already been merged, and can even apply changes to files that
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have been renamed.
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------------------------------------
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We want to keep our changes available for other people, even if they
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aren't quite complete yet. So we will create a new public branch on
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``centralhost``, and track it locally.
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aren't quite complete yet. So we will create a new public branch, and
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% cd ~/work/sigil
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% bzr branch bzr+ssh://centralhost/srv/bzr/sigil \
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bzr+ssh://centralhost/srv/bzr/sigil/doodle-fixes
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% bzr checkout bzr+ssh://centralhost/srv/bzr/sigil/doodle-fixes doodle-fixes
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% bzr branch sftp://centralhost/srv/bzr/sigil \
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sftp://centralhost/srv/bzr/sigil/doodle-fixes
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% bzr checkout sftp://centralhost/srv/bzr/sigil/doodle-fixes doodle-fixes
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% cd doodle-fixes
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We now have a place to make any fixes we need to ``doodle``. And we would
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not interrupt people who are working on other parts of the code. Because
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we have a checkout, any commits made in the ``~/work/sigil/doodle-fixes/``
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will also show up on ``centralhost``. [#nestedbranches]_ It is also
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possible to have two developers collaborate on one of these branches, just
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like they would have collaborated on the ``dev`` branch. [#cbranch]_
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.. [#nestedbranches] It may look odd to have a branch in a subdirectory of
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another branch. This is just fine, and you can think of it as a
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hierarchical namespace where the nested branch is derived from the
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We now have a place to make any fixes to doodles that we need. And we
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won't interrupt people who are working on other parts of the code.
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Because we have a checkout, any commits made in the ``doodle-fixes/`` will
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also show up on ``centralhost``. [#nestedbranches_]
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It is also completely possible to have 2 developers collaborate on one of
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these branches, just like they would have collaborated on the ``dev``
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.. [#cbranch] When using lots of independent branches, having to retype
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the full URL all the time takes a lot of typing. We are looking into
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Which is designed to take a base branch, create a new public branch,
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and create a checkout of that branch, all with much less typing.
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Configuring ``cbranch`` is outside the scope of this document, but the
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final commands are similar to:
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% bzr cbranch dev my-feature-branch
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.. _bzrtools: http://wiki.bazaar.canonical.com/BzrTools
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final commands look like ``bzr cbranch dev my-feature-branch``
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.. [#nestedbranches] It may look odd to have a branch in a subdirectory of
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another branch. However, this is just fine, and you can think of it as
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a heirarchial namespace. Where the nested branch is derived from the
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.. _bzrtools: https://launchpad.net/products/bzrtools
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Merging changes back
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--------------------
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When it is decided that some of the changes in ``doodle-fixes`` are ready
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to be merged into the main branch, simply do::
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When it is decided that some of the changes in ``doodle-fixes`` is ready
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to be merged into the main tree, simply do::
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% cd ~/work/sigil/dev
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% bzr merge ../doodle-fixes
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Now the changes are available in the ``dev`` branch, but they have not
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been committed yet. This is the time when you want to review the final
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changes, and double check the code to make sure it compiles cleanly and
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passes the test suite. The commands ``bzr status`` and ``bzr diff`` are
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good tools to use here. Also, this is the time to resolve any conflicts.
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Bazaar_ will prevent you from committing until you have resolved these
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conflicts. That way you don't accidentally commit the conflict markers.
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The command ``bzr status`` will show the conflicts along with the other
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changes, or you can use ``bzr conflicts`` to just list conflicts. Use
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``bzr resolve file/name`` or ``bzr resolve --all`` once conflicts have
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been handled. [#resolve]_ If you have a conflict that is particularly
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difficult to solve you may want to use the ``bzr remerge`` command. It
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will let you try different merge algorithms, as well as let you see the
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original source lines (``--show-base``).
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Now the changes are available in the ``dev`` branch, but they haven't been
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committed yet. This is the time when you want to review the final changes,
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and make sure they are what you want. ``bzr status`` and ``bzr diff`` are
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good tools to use here. Also, there may be some conflicts in files, if
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there were changes made to the same file. Bazaar_ will prevent you from
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committing until you have resolved these conflicts. That way you don't
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accidentally commit the conflict markers. ``bzr status`` will show the
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conflicts along with the other changes, or you can use ``bzr conflicts``
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to just list conflicts. Use ``bzr resolve file/name`` or ``bzr resolve
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--all`` once conflicts have been handled.[#resolve]_
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If you have a conflict that is particularly difficult to solve you may
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want to use the ``bzr remerge`` command. It will let you try different
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merge algorithms, as well as let you see the original source lines
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.. [#resolve] Some systems make you resolve conflicts as part of the merge
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process. We have found that it is usually easier to resolve conflicts
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Shared Repository
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-----------------
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Bazaar_ has the concept of a "Shared Repository". This is similar to
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the traditional concept of a repository in other VCSs like CVS and
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Subversion. For example, in Subversion you have a remote repository,
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which is where all of the history is stored, and locally you don't
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have any history information, only a checkout of the working tree
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files. Note that "Shared" in this context means shared between
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branches. It *may* be shared between people, but standalone branches
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can also be shared between people.
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In Bazaar_ terms, a "Shared Repository" is a location where multiple
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branches can **share** their revision history information. In order to
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support decentralized workflows, it is possible for every branch to
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store its own revision history information. But this is often
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inefficient, since related branches share history, and they might as
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well share the storage as well.
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Bazaar_ has the concept of a `Shared Repository`_. This is similar to the
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concept of other RCS's repository. Such as in Subversion, where you have a
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remote repository, which is where all of the history is stored, and
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locally you don't have any history information, only a checkout of the
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working tree files. Note that "Shared" in this context means shared
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between branches. It *may* be shared between people, but standalone
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branches can also be shared between people.
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In Bazaar_ terms, a `Shared Repository`_ is a location where multiple
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branches can **share** their revision history information. Because Bazaar_
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wants to support decentralized workflows, it is possible for every branch
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to maintain its own revision history information. But this is often
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inefficient, since often branches share history, and they might as well
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share the storage as well.
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doc/centralized_workflow.txt
