This document describes the process ordinarily used for Open vSwitch development and release. Exceptions are sometimes necessary, so all of the statements here should be taken as subject to change through rough consensus of Open vSwitch contributors, obtained through public discussion on, e.g., ovs-dev or the #openvswitch IRC channel.
Open vSwitch feature development takes place on the "master" branch. Ordinarily, new features are rebased against master and applied directly. For features that take significant development, sometimes it is more appropriate to merge a separate branch into master; please discuss this on ovs-dev in advance.
Periodically, the OVS developers fork a branch from master to become an official release. These release branches are named for expected release number, e.g. "branch-2.3" for the branch that will yield Open vSwitch 2.3.x. Release branches should receive only bug fixes, not new features. Bug fixes applied to release branches should be backports of corresponding bug fixes to the master branch, except for bugs present only on release branches (which are rare in practice).
Sometimes there can be exceptions to the rule that a release branch receives only bug fixes. In particular, after a release branch is created, but before the first actual release from that branch, it can be appropriate to add features. Like bug fixes, new features on release branches should be backports of the corresponding commits on the master branch. Features to be added to release branches should be limited in scope and risk and discussed on ovs-dev before creating the branch.
After a period of testing and stabilization, and rough consensus obtained from contributors that the release is ready, the developers release the .0 release on its branch, e.g. 2.3.0 for branch-2.3. To make the actual release, a developer pushes a signed tag named, e.g. v2.3.0, to the Open vSwitch repository, makes a release tarball available on openvswitch.org, and posts a release announcement to ovs-announce.
As a number of bug fixes accumulate, or after important bugs or vulnerabilities are fixed, the OVS developers may make additional releases from a branch: 2.3.1, 2.3.2, and so on. The process is the same for these additional release as for a .0 release.
At most two release branches are formally maintained at any given time: the latest release and the latest release designed as LTS. An LTS release is one that the OVS project has designated as being maintained for a longer period of time. Currently, an LTS release is maintained until the next LTS is chosen. There is not currently a strict guideline on how often a new LTS release is chosen, but so far it has been about every 2 years. That could change based on the current state of OVS development. For example, we do not want to designate a new release as LTS that includes disruptive internal changes, as that may make it harder to support for a longer period of time. Discussion about choosing the next LTS release occurs on the OVS development mailing list.
The version number on master should normally end in .90. This indicates that the Open vSwitch version is "almost" the next version to branch.
Forking master into branch-x.y requires two commits to master. The first is titled "Prepare for x.y.0" and increments the version number to x.y. This is the initial commit on branch-x.y. The second is titled "Prepare for post-x.y.0 (x.y.90)" and increments the version number to x.y.90.
The version number on a release branch is x.y.z, where z is initially 0. Making a release requires two commits. The first is titled "Set release dates for x.y.z." and updates NEWS and debian/changelog to specify the release date of the new release. This commit is the one made into a tarball and tagged. The second is titled "Prepare for x.y.(z+1)." and increments the version number and adds a blank item to NEWS with an unspecified date.
Open vSwitch makes releases at the following six-month cadence, which of course is subject to change.
| Time (months) | Approximate Dates | Event |
|---|---|---|
| T | Apr 1, Oct 1 | Release cycle for version x.y begins |
| T + 4 | Aug 1, Feb 1 | branch-x.y forks from master |
| T + 5.5 | Sep 15, Mar 15 | branch-x.y released as version x.y.0 |
Please use [email protected] to discuss the Open vSwitch development and release process.