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Revision as of 16:42, 28 March 2013

OpenStack branch model

Starting with the Diablo cycle, OpenStack core projects use a branching model close to the NVIE model that ensures an almost-always-open master while still allowing to freeze features and select bugfixes in a release branch (milestone-proposed):


At some point before the release of a milestone (called the "branch point"), the milestone-proposed branch gets created out of the master branch. The master branch continues towards the development of the next milestone. The milestone-proposed branches gets testing and backported bugfixes (that must land in master first), until the release is tagged.

Version numbers

Since we produce artifacts that are leading up to a release and drive a lot of automation, we produce automatic version numbers. Prior to Grizzly, we used a different versioning scheme, which remains documented at OldVersionNumbers

For projects with milestones and releases (Nova, Glance):

  • The master branch generates VERSION~DEVMILESTONE~DATE.TRUNKREV (nova-2011.3~d2~20110531.302.tar.gz)
  • The milestone-proposed branch generates VERSION~MILESTONE~DATE.rMPREV (nova-2011.3~d1~20110531.r301.tar.gz)
  • This gets copied at milestone delivery time to VERSION~MILESTONE (nova-2011.3~d1.tar.gz)
  • This gets copied at coordinated release time as VERSION (nova-2011.3.tar.gz)

For projects where milestones == releases (Swift):

  • The master branch generates VERSION~DATE.TRUNKREV (swift-1.4.1~20110531.302.tar.gz)
  • The milestone-proposed branch generates VERSION~DATE.rMPREV (swift-1.4.0~20110531.r301.tar.gz)
  • This gets copied at release time as VERSION (swift-1.4.0.tar.gz)


  • VERSION being the version of the project under development (2011.3, 1.4.0)
  • DEVMILESTONE being the short name of milestone under development (d2) and MILESTONE being the milestone about to be released (d1)
  • DATE being under YYYYMMDD form
  • TRUNKREV is a sequential revision on master
  • MPREV is a sequential revision on milestone-proposed

Those (seemingly complex) version numbers actually ensure that you can smoothly upgrade in all scenarios (from trunk to milestone-proposed and back to trunk and to the final version...)