Release plan

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Note  As of December 2015, the release plan is in the process of being changed so that the description below will no longer be accurate:
Cquote1.png Hi Everybody,

Today, December 17th would be the day to announce the feature freeze for 3.8 if we were following the usual release schedule.

A while ago I proposed a change in that schedule and I have spent some time on preparing the scripts for an automated release process since then. I think I have pretty much everything ready to go for automated releases and now I'd like to give it a first try for the 3.8 release next year.

For the first execution, I'd like to trigger the scripts manually on my local machine instead of Jenkins to have some better control of it. If it works out as expected, I'll put this onto our Jenkins server afterwards to be executed automatically for the release following after 3.8.

For now, I propose the following and would do so if nobody objects:

  • There is no feature freeze for the next (3.8) and the following releases
  • On Jan., 17th I trigger my first script to create release/3.8 branches with version 3.8.1 (!)
  • Immediately after that I let Jenkins create the binaries for 3.8.1 and we have our first release
  • Patches going into the release/3.8 branch automatically trigger a new build with a previous increase of the micro version number (3.8.2, 3.8.3,..) and we immediately have a bugfix release
  • On 'next', version numbers go to 3.9.0
  • Nightly builds are created from next after every push in that branch

After a to-be-defined period (my proposal: 3 month) we start over:

  • Create a release/3.9 branch with version 3.9.1
  • etc. etc.

Note: there will be no odd-even version number scheme (odd equals unstable, even equals stable). Instead, x.x.0 is unstable, nightly from next and x.x.n where n >= 1 is a stable release.

If everything works as expected, we have a major release every to-be-defined months, a bugfix release after every push to the release branch and a nightly build after every push to 'next'.

I hope this sounds reasonable and keeps everybody happy.

Feedback welcome.

— Torsten Dreyer (Dec 17th, 2015). [Flightgear-devel] Relesae 3.8.
(powered by Instant-Cquotes)
Current release: 2020.1 (11 May 2020)
Next release: 2020.2 (120 days from now)
See release plan for details.

The release plan is the process by which a new version of FlightGear is released. The release plan is actually a continual work-in-progress, and is refined with every new release.

The original release plan.

FlightGear has had two release plans over history. The original release plan was developed by Mathias Fröhlich, Martin Spott, Thorsten Brehm and Torsten Dreyer during LinuxTag 2011.

To suggest improvements and/or changes to the release plan, it is recommended to get in touch via the mailing list. Improvements can be based on the lessons learned from previous releases.

General release concept (old release plan)

New FlightGear releases are scheduled twice a year. The magic number to remember is 17. On the 17th of January (the first month) and July (the seventh month), a new release branch is created for SimGear, the FlightGear source, and fgdata.

Cquote1.png As a clarification: We do not enter a code freeze but a feature freeze. Code changes are welcome after December 17th as long as it is guaranteed (not just "unlikely") that they do not introduce any side effects and become a release blocker. It is the sole responsibility of the committer to decide if that is the case or not. Every new feature that didn't make it into the repository by the deadline may probably easily wait for another four weeks to get committed. Remember: most aircraft are not affected by the feature freeze and aircraft developers quickly adopt and use new features as they become available
— Torsten Dreyer (16th Nov 2012). [Flightgear-devel] Next FlightGear release (Feb. 17 2013).

After branching, there is one month for bug fixing in the release branch, so building and packing of the binaries and fgdata takes place around the 18th of February and the 18th of August. Allowing a few days for distribution of the files, new versions should be publicly available around the 20th of February and August.

The development stream of SimGear, FlightGear, and fgdata is set into a frozen state one month before the branch-day (17th), to let the dust of development settle and to allow fixing the most annoying bugs in the code. During this period, developers should not add any new features, subsystems, and the like. Immediately after the stream has branched for the release, development in the main stream (next/master) is open for major changes until one month before the next branch-day. This results in a duty cycle of 5 month developing and 1 month thinking.

Version numbers

FlightGear version numbers consist of three digits, separated by dots:

Before 2016.1

  • Major (3.4.0): Only increased after significant changes to the functionality of the software (e.g., 1.x.x → 2.0.0 (due to switch to OSG).
  • Minor (3.4.0): Has two applications:
    • Stable releases always have even numbers (e.g. 2.8.0, 2.10.0, 2.12.0).
    • The latest Git version or nightly build uses an odd number, always one more than the latest stable release's minor revision numbere. For example, when the latest release was 3.4.0, the current development stream was 3.5.0.
  • Revision (3.4.0): Increased by bugfix releases (e.g., 2.12.1).

2016.1 and after

  • Year (2016.1.0): The year the version was released.
  • Number (2016.1.0): Which release of the year the version is (note: starts at 1).
  • Revision (2016.1.0): Indicates one of two things:
    • In the latest Git version or nightly build, this digit is 0, indicating that it is unstable.
    • When a new release is created, this digit is set to 1. With bugfix that is made, this digit is increased by 1, and a new version created.
Note  In general, release are referred to by their first two digits (e.g., 3.4). However, when filing a bug report or debugging problems, it is a good idea to give the full release number.

Detailed time schedule and checklist

  1. Dec/Jun 17th: Development stream is declared "frozen" or "yellow"
    1. Send a mail to the flightgear-devel mailing-list to announce the state, add a call for screenshots
    2. Create a "release preperations" topic at the forum and make it a "Global Announcement", add a call for screenshots
    3. Ask for translator for a review of the translations of the menu, help and startup entries in case there have been some mods on those files
    4. Change the content of wiki template at Template:GitStatus to {{GitStatus:frozen}}
    5. Bump up the version-number of simgear/next, flightgear/next, fgrun/next and fgdata/master to an even number (2.9.0 -> 3.0.0)
    6. Compile and test drive FlightGear with the new version-number
    7. Commit the new version number to next (flightgear+simgear+fgrun) and master(fgdata)
    8. Tag (annotated) flightgear, simgear, fgrun and fgdata with version/3.0.0
      git tag -a version/3.0.0 (Enter a wise comment)
    9. Push the branches next/master and the tags upstream
      for flightgear, fgrun and simgear: git push origin next
      for fgdata: git push origin master
      for the tags (all repos): git push origin version/3.0.0
  2. Jan/Jul 17th: Create new release branch, assign new version number to dev-stream, re-open streams
    1. Pull current Git, create the release branches (for sg/fg/fgrun/fgdata):
      git pull
      git branch release/3.0.0
    2. On the next/master branches, bump up the version-number of simgear, flightgear, fgrun and fgdata to an odd number (3.0.0 -> 3.1.0)
    3. Compile and test drive FlightGear with the new development version number
    4. Commit the changes of version-number to next/master
    5. Tag (annotated) flightgear, simgear, fgrun and fgdata with "version/2.9.0"
      git tag -a version/2.9.0 (Enter a wise comment)
    6. Push the branches next/master and release/3.0.0 and the tags upstream
      for flightgear, simgear, fgrun and fgdata: git push origin release/3.0.0
      for flightgear, fgrun and simgear: git push origin next
      for fgdata: git push origin master
      for the tags (all repos): git push origin version/3.1.0
    7. Declare dev-streams "open" or "green"
      Ask a wiki admin to change the content of wiki template at Template:GitStatus to {{GitStatus:open}}
      Send a mail to the flightgear-devel mailing-list to announce the state.
    8. Trigger James or Clément for the Jenkins-builds and Curt for a snapshot release and ThorstenB for the OpenSuse build
      in fgmeta:
      git checkout release/3.0.0
      git submodule foreach git checkout release/3.0.0
      git submodule foreach git pull -r
      git add .
      git commit -m "Bump revision"
      git push origin release/3.0.0
  3. Feb/Aug 1st: Start preparing the release notes and a press announcement
  4. Feb/Aug 17th: Create binaries/installers, pack fgdata, publish files, announce new version, close the release-branch.
    1. Generate latest getstart.pdf, push the PDF to fgdata/master - and cherry-pick to the release branch. Generate latest getstart HTML, push PDF and HTML to the MapServer site.
    2. Tag the release/3.0.0 branches of simgear, flightgear, fgrun and fgdata and push the tags.
      for flighgear, simgear, fgrun and fgdata: git tag version/3.0.0-final
      for flighgear, simgear, fgrun and fgdata: git push origin version/3.0.0-final
    3. Merge the branch release/3.0.0 into master (NOT next) for flightgear and simgear and push the branch
      We don't have a next branch for fgdata, no merging of the release branch here.
      for flighgear, fgrun and simgear:
      git checkout -b master origin/master or git checkout master if you already have the local branch
      git merge version/3.0.0-final
      git push origin master
    4. Core developers and other contributors should be invited to add their release related experiences (i.e. suggestions for improvements) to the wiki to help update and improve the release plan (i.e. this page) accordingly.

To bump up the version number

Definition of repository states

State Description
Traffic light green.png Open/Green Normal development of the code base and fgdata. Unrestricted (well, sort of) access to the streams. This state lasts for five months after the release branches were created.
Traffic light yellow.png Frozen/Yellow No new features or major changes shall be pushed onto the development streams (neither source nor data). This period is for preparing the code for the release and make sure there are no major issues. It lasts for four weeks until creation of the release branches.

It's a good idea for aircraft developers to adhere to this rule. However, aircraft in fgdata may be handled as an exception from the frozen state. Any change to aircraft may be pushed to the repository if it is guaranteed that this change does not affect any other aircraft or system and if no file outside the root directory of that specific aircraft is changed. Also, aircraft defined as part of the base package (e.g. the c172p) enter the frozen state and shall not undergo major changes in that period.

Traffic light red.png Closed/Red Nothing shall be pushed to the development streams (simgear, flightgear, fgrun and fgdata). This state is for creating the release branches. It lasts for just a few hours on Jan 17th and Jul 17th around 12:00 UTC.

Bug fix committing policy

Fixes for bugs during the shakedown test of the release branch may be applied to the branches next or release/2.8.0. A fix goes into release/2.8.0 if the development of next has moved forward and this fix does not apply there. It also goes into the release branch if there will be a better fix for next. A fix goes into next if it is also solves an issue for the next version. Cherry-pick this commit into the release/2.8.0 branch.

DO NOT merge next into release/2.8.0 or vice versa. Most likely, there will be commits that are not welcome in or even break the other branch.

Bug tracking

The bugtracker will be our primary source for the bug fixing period. Bugs reported on the mailing list or forum will not be tracked! Reporters shall be requested to file a bug report at the bugtracker. Bugs shall be assigned a priority and a keyword to make the assignment to a developer easier. Bug reports that can't be confirmed or need more input from the reporter to get fixed will be assigned a new state "stalled" and only processed after more information has been provided. Bugs assigned a high priority will be downgraded, if no progress has been made over a certain amount of time. This is to prevent the release from being blocked by a bug that no developer is able (or willing) to fix. The only exception is "does not compile for one of the major platforms", which certainly is a release-blocker.

Bugs that were present in the latest stable release, and now considered "fixed", should be assigned a milestone label, corresponding with the upcoming stable release number. By doing so, they'll end up in the list of fixed bugs.

Tasks and owners

The following table should be updated and augmented after each release, according to the Lessons learned section below.

Stage Task Owner(s)
Preparation Announce the state-change of the dev-streams, cross-post to JSBSim list (see lessons learned!) TorstenD
Create/maintain the git branches TorstenD
Track the bugs on the tracker, trigger developers, adjust bug-priorities ThorstenB, Gijs, James, ...
Sync the language files so they can be translated ThorstenB, James
Beta testing EVERYBODY
Update documentation: FAQ, The Manual, wiki Stuart, Gijs and anyone else
Pack RC and final version of fgdata
Create the RC and final version Source-tarball Curt
Linux ThorstenB (for openSUSE)
Windows Curt
MacOS Tat/James
Distribute files to download servers Curt
Make adjustments on the web-site Collect/make screenshots for the gallery Curt
Generate aircraft page Curt, Gijs
Tag the newsletter template according to the released version

[[Category:Changes after 2.12]]

Hooray, Gijs, Stuart (other wiki admins)
Announce the new version to the public Write a changelog: Next changelog All developers/contributors
Contact flightsim websites and send them/link them to the "press announcement". See release promotion for a list of already-contacted and yet-to-contact websites/magazines. EVERYBODY

Open items, questions

  • Automate and/or document the creation of RC's: "We need to get this automated some day. Or at least documented...(another one from "famous last words": if you have to do it more than once, automate it. If you can't automate it, document it."[1]
  • Automate the creation of Windows and Mac installers Done Done [2] (see FlightGear Build Server)
  • Automate the creation of fgdata distribution
  • Possibly try to find a way to automate testing of updated jsbsim code, so that the chance for breakage is reduced by running scripted tests [3][4][5]

Lessons learned

See Release plan/Lessons learned for a list of things that turned out well and should be kept for the next release as well as thing that didn't turn out so well and should be changed for future releases. Ideally, the release plan should be updated and augmented so that the lessons learned are incorporated accordingly.