OVN Release Process

This document describes the process ordinarily used for OVN development and release. Exceptions are sometimes necessary, so all of the statements here should be taken as subject to change through rough consensus of OVN contributors, obtained through public discussion on, e.g., ovs-dev or the #openvswitch IRC channel.

Release Strategy

OVN feature development takes place on the “main” branch. Ordinarily, new features are rebased against main and applied directly. For features that take significant development, sometimes it is more appropriate to merge a separate branch into main; please discuss this on ovs-dev in advance.

The process of making a release has the following stages. See Release Scheduling for the timing of each stage:

  1. “Soft freeze” of the main branch.

    During the freeze, we ask committers to refrain from applying patches that add new features unless those patches were already being publicly discussed and reviewed before the freeze began. Bug fixes are welcome at any time. Please propose and discuss exceptions on ovs-dev.

  2. Fork a release branch from main, named for the expected release number, e.g. “branch-2019.10” for the branch that will yield OVN 2019.10.x.

    Release branches are intended for testing and stabilization. At this stage and in later stages, they should receive only bug fixes, not new features. Bug fixes applied to release branches should be backports of corresponding bug fixes to the main branch, except for bugs present only on release branches (which are rare in practice).

    At this stage, sometimes there can be exceptions to the rule that a release branch receives only bug fixes. Like bug fixes, new features on release branches should be backports of the corresponding commits on the main branch. Features to be added to release branches should be limited in scope and risk and discussed on ovs-dev before creating the branch.

  3. When committers come to rough consensus that the release is ready, they release the .0 release on its branch, e.g. 2019.10.0 for branch-2019.10. To make the actual release, a committer pushes a signed tag named, e.g. v2019.10.0, to the OVN repository, makes a release tarball available on openvswitch.org, and posts a release announcement to ovs-announce.

  4. As bug fixes accumulate, or after important bugs or vulnerabilities are fixed, committers may make additional releases from a branch: 2019.10.1, 2019.10.2, and so on. The process is the same for these additional release as for a .0 release.

Long-term Support Releases

The OVN project will periodically designate a release as “long-term support” or LTS for short. An LTS release has the distinction of being maintained for longer than a standard release.

LTS releases will receive bug fixes until the point that another LTS is released. At that point, the old LTS will receive an additional year of critical and security fixes. Critical fixes are those that are required to ensure basic operation (e.g. memory leak fixes, crash fixes). Security fixes are those that address concerns about exploitable flaws in OVN and that have a corresponding CVE report.

LTS releases are scheduled to be released once every two years. This means that any given LTS will receive bug fix support for two years, followed by one year of critical bug fixes and security fixes.

Release Numbering

The version number on main should normally end in .90. This indicates that the OVN version is “almost” the next version to branch.

Forking main into branch-x.y requires two commits to main. 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 x is the current year, y is the month of the release, and 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.

Release Scheduling

OVN makes releases at the following three-month cadence. All dates are approximate:

Time (months) Example Dates Stage
T Dec 1, Mar 1, … Begin x.y release cycle
T + 2 Feb 1, May 1, … “Soft freeze” main for x.y release
T + 2.5 Feb 15, May 15, … Fork branch-x.y from main
T + 3 Mar 1, Jun 1, … Release version x.y.0

Release Calendar

The 2022 timetable is shown below. Note that these dates are not set in stone. If extenuating circumstances arise, a release may be delayed from its target date.

Release Soft Freeze Branch Creation Release
22.03.0 Feb 4 Feb 18 Mar 4
22.06.0 May 6 May 20 Jun 3
22.09.0 Aug 5 Aug 19 Sep 2
22.12.0 Nov 4 Nov 18 Dec 2

Below is the 2023 timetable

Release Soft Freeze Branch Creation Release
23.03.0 Feb 3 Feb 17 Mar 3
23.06.0 May 5 May 19 Jun 2
23.09.0 Aug 4 Aug 18 Sep 1
23.12.0 Nov 3 Nov 17 Dec 1

Contact

Use dev@openvswitch.org to discuss the OVN development and release process.