.. index:: Obtain Patch

.. _ObtPatch:

Obtain a patch
==============

You can obtain patches in three different ways:

* In some cases, the community or an OpenStack distribution vendor supplies a pre-generated patch for download.

* For stable release bugfix updates, you can download a cumulative version of OpenStack packages that each contains the fixes for that component.

* You can also download patches from github.com, git.openstack.org (also the repository browser), and directly from local git repository. Examples of using these methods follow.

.. note:: The first two methods can only generate patches for a single commit. If you need to generate a patch from changes resulting from many commits, use the git method.

github.com method
-----------------

To generate a patch file from a github commit, simply add ``.patch`` at the
end of your commit URL.

For example, to change the following commit URL to a patch URL:

https://github.com/openstack/nova/commit/8b9f924306ffa35b2a87cd6ec5adc28159bc78c1

Type:

https://github.com/openstack/nova/commit/8b9f924306ffa35b2a87cd6ec5adc28159bc78c1.patch

git.openstack.org method
------------------------

Using the git.openstack.org web interface, find a commit. Navigate to the
"commit" tab and download the patch file named ``(patch)``.

.. image::  /_images/patchcommit.png
  :align: center
  :width: 100%

Local git repository method
---------------------------

First, you will need to fetch repository data `using git <http://git-scm.com/book/en/Git-Basics-Getting-a-Git-Repository>`_.

Check git format-patch help for details::

  $ git format-patch -h
  usage: git format-patch [options] [<since> | <revision range>]

      -n, --numbered        use [PATCH n/m] even with a single patch
      -N, --no-numbered     use [PATCH] even with multiple patches
      -s, --signoff         add Signed-off-by:
      --stdout              print patches to standard out
      --cover-letter        generate a cover letter
      --numbered-files      use simple number sequence for output file names
      --suffix <sfx>        use <sfx> instead of '.patch'
      --start-number <n>    start numbering patches at <n> instead of 1

Suppose you want to generate a patch from the last 10 commits. Use the following
command starting from most recent commit in your local repo::

  $ git format-patch -10 HEAD --stdout > 0001-last-10-commits.patch
  A sample patch follows:
  +++ contex.py   2014-01-07 12:26:14.793787101 +0000
  --- /usr/share/pyshared/nova/context.py	2013-10-17 14:15:04.000000000 +0000
  @@ -21,6 +21,7 @@

   import copy
   import uuid
  +import time

   from nova import exception
   from nova.openstack.common.gettextutils import _
  +++ baserpc.py  2014-01-07 12:29:57.513881636 +0000
  --- /usr/share/pyshared/nova/baserpc.py	2013-10-17 14:15:04.000000000 +0000
  @@ -40,6 +40,7 @@

           1.0 - Initial version.
           1.1 - Add get_backdoor_port
  +        1.2 - New version
       """