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Migrating between version control systems can be a complicated process, and
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Bazaar has extensive documentation on the process at
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http://doc.bazaar.canonical.com/migration/en and we won't attempt to repeat that
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here. We will try to give a few motivating examples for conversion from
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Mercurial and Subversion.
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In many projects wishing to use Bazaar, there is pre-existing history for the
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codebase that should be taken into consideration. Bazaar leverages an
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interchange format originally developed for Git called `fast-import` to
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provide migration strategies for many other version control systems. To
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work with fast-import files, Bazaar needs the `fastimport`_ plugin. This can
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be installed as with any Bazaar plugin.
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.. _fastimport: http://launchpad.net/bzr-fastimport
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The way that fast-import can be used for migration is to export the existing
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history into a fast-import file, then use the ``bzr fast-import`` command.
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The `fastimport` plugin includes exporters for Subversion, CVS, Git, Mercurial
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and darcs, accessible as the ``fast-export-from-XXX`` commands. Note that
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``fast-import`` should not be used in a branch with existing history.
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Assuming that ProjectX was first developed in Mercurial before switching to
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Bazaar, and that the Mercurial repository is in ``/srv/hg/projectx``, the
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following commands will import that history into a newly created ``trunk``
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branch. (Recall that in `Further Configuration
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<simple-setups.html#further-configuration>`_ we created the
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``/srv/bzr/projectx`` directory as a shared repository.)
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$ cd /srv/bzr/projectx
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$ bzr fast-export-from-hg ../../hg/projectx projectx.fi
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$ bzr fast-import projectx.fi trunk
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As the most common centralized version control system, migration from
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Subversion is particularly important for any *new* version control system.
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Bazaar's `svn`_ plugin provides tools for interaction with Subversion
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projects. In fact, Bazaar can be used transparently with projects stored in
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Subversion, but that is beyond the scope of this document. (See
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http://doc.bazaar.canonical.com/en/migration/foreign/bzr-on-svn-projects.html for
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more on that subject.) What is relevant here is the ``svn-import`` command
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provided by that plugin. This can import an entire subversion repository
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including tags and branches, particularly if they are stored in Subversion's
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recommended directory structure: ``/tags/``, ``/branches/`` and ``/trunk/``.
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This command has flexible ways to specify what paths within the Subversion
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repository contain branches and which contain tags. For example, the
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recommended layout for Subversion projects (called ``trunk`` by the svn
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plugin) could be specified in ``~/.bazaar/subversion.conf`` as
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[203ae883-c723-44c9-aabd-cb56e4f81c9a]
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This allows substantially complicated Subversion repositories to be converted
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into a set of separate Bazaar branches. After installing the svn plugin, see
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``bzr help svn-import`` and ``bzr help svn-layout``.
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.. _svn: http://launchpad.net/bzr-svn
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.. TODO: Legacy VCS to bzr sync. Tailor? Incremental conversions?
added
removed
doc/en/admin-guide/migration.txt
