5
:status: Current policy, as of 2017-11.
8
Our users want easy access to bug fixes without other changes to the
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core product. They also want a Just Works experience across the full
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Breezy ecosystem. To deliver the first and enable the second, we're
11
adopting some standard process patterns: a 6 monthly release cycle and a
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stable series. These changes will also have other benefits, including
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better availability of bug fixes in OS distributions, more freedom to
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remove old code, and less work for in packaging.
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* `Breezy Developer Document Catalog <index.html>`_
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* `Releasing Bazaar <releasing.html>`_ -- the process for actually making
21
a release or release candidate.
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Breezy will make a major release every six months, which will be supported at
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least until the time of the next major release and generally 18 months after
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the first final release in a series. During this support period, we'll make
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incremental releases which fix bugs, but which do not change network or disk
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formats or command syntax, and which do not require updates to plugins.
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We will also run a development series, which will become the next major
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release. We'll make a beta release from this every four weeks. The
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beta releases will be as stable as our current monthly releases and
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completely suitable for everyday use by users who can tolerate changes
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Having the stable series isn't a reason to cut back on QA or to make the
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trunk or development releases unstable, which would only make our job
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harder. We keep our trunk in an always-releasable state, and that should
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continue: any beta release could potentially be supported in the long
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term, but we identify particular releases that actually will be supported.
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The trunk will never be frozen: changes that pass review, other quality
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checks and that are agreed amongst the developers can always be landed
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into trunk. The only restrictions will be on branches specifically
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targeted at a release.
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2.0.0 --- 2.0.1 -- 2.0.2 -- ...
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+--2.1.0beta1 -- 2.1.0beta2 -- ... -- 2.1.0rc1 -- 2.1.0 -- 2.1.1 -- ...
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Starting from the date of a major release:
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At four-week intervals we make a new beta release. There will be no
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separate release candidate, but if a serious problem is discovered we may
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do the next beta ahead of schedule or make a point release. There will be
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about five or six releases in that series.
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In parallel with this, bugs targeted to the previous major release are
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merged into its branch. We will make bugfix releases from that branch as
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appropriate to the accumulation of changes, perhaps monthly, perhaps more
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often if there are serious bugs, perhaps much less often if no new changes
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We will synchronize our major releases with Ubuntu, so that they come out
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in sufficient time for some testing and margin of error before Ubuntu's
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We value regular releases. We prefer to slip a feature or fix to
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a later release rather than to make a release late. We will normally only
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slip a release to fix a critical bug.
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The number for a six-month cycle is chosen at the start, with an increment
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to either the first field (3.0.0) or second field (3.1.0) depending on
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what we expect to be the user impact of the release. We expect releases
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that culminate in a new disk format or that require changes in how people
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use the tool will get a new major number. We can change (forward only) if
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it turns out that we land larger changes than were expected.
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We will always use the 3-digit form (major.minor.micro) even when
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referring to the initial major release. This should help clarify where a
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patch is intended to land. (eg, "I propose this for 2.0.0" is clear, while
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"I propose this for 2.0" could mean you want to make the 2.0.0 release, or
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that you just want to land on the 2.0.x stable release series.)
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Major releases (2.0.0 or 2.1.0)
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The big ones, every six months, intended to ship in distributions and
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to be used by stability-oriented users.
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Release candidate (2.0.0rc1)
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A preview of a major release, made one or a few weeks beforehand at the
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time the release branch is created. There should be few if any changes
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from the rc to the stable release. We should avoid the confusing phrasing
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"release candidate 2.0.0rc1 is released"; instead use "available."
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Starting with the 2.3 series we don't plan on making release candidates
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Bugfix releases (2.0.1)
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Based on the previous major release or bugfix; contains only bugfixes
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and perhaps documentation or translation corrections.
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A major release and its descendant bugfix releases.
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Either a major release or a bugfix release.
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Beta release (3.0.0beta1)
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Made from trunk every month, except for the month there's a major
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release. Stable and suitable for users who want the latest code and
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can live with some changes from month to month.
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The development releases leading up to a stable release.
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Bug fixes should normally be done first against the stable branch,
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reviewed against that branch, and then merged forward to trunk.
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It may not always be easy to do this, if fixing the bug requires large
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changes or the affected code is different in the stable and development
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branches. If the tradeoff does not seem worthwhile the bug can be fixed
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only in the development branch, at least in the first instance. If users
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later want the fix backported we can discuss it.
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Developers can merge the release branch into trunk as often as they like,
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only asking for review if they're making nontrivial changes or feel review
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Feature and Performance Work
165
----------------------------
167
Features can be landed to the development branch at any time, and they'll
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be released for testing within a month.
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Performance bugs, although important, will generally not be landed in a
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stable series. Fixing performance bugs well often requires nontrivial
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code changes or new formats. These are not suitable for a stable series.
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Performance bugs that can be fixed with a small safe patch can be
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considered for the stable series.
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Plugins that want to cooperate with this should make a series and a branch
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that matches each bzr stable series, and follow similar rules in making
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releases from their stable branch. We'd expect that plugins will make a
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release between the first beta release of a series and the final major
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Within a stable series, anything that breaks any known plugin is
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considered an API break and will be avoided. Before
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making each bugfix release, we'll test that code against important
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Within a development series, the focus is on helping plugin authors keep
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up to date by giving clear error messages when an interface is removed.
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We will no longer focus on letting old plugin code work with new versions
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of breezy, which is an elusive target in Python.
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This may mean that in cases where today a plugin would keep running but
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give warnings, it will now fail altogether with an error.
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In return we expect more freedom to change and cleanup breezy code without
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needing to keep old code around, or write extra compatibility shims, or
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have review turnarounds related to compatibility. Some changes, such as
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removing module-global variables, that are hard to do now, will be
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possible to do safely.
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Discussion of plugins here includes programs that import and use breezy
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but that aren't technically plugins. The same approach, though the
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technical considerations are different, should apply to other extensions
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such as programs that use bzr through the shell interface.
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Data and Network Formats
214
------------------------
216
Any development release should be able to interoperate with the previous
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stable release, and any stable release should be able to interoperate with
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the previous stable release. This is a minimum and normally releases will be
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able to interoperate with all previous releases as at present.
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Each major release will have one recommended data format which will be the
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default. The name of the format will indicate which release series (not
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specific release) it comes from: '2a' is the first supported format for
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the 2.0.x series, '2b' the second, etc. We don't mention the particular
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release that introduced it so as to avoid problems predicting precisely
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During a development series we may have a series of experimental formats.
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We will not leave people stranded if they test these formats, but we also
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won't guarantee to keep supporting them in a future release. If something
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inserted in one development release turns out to be bad it can just be
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The guarantees made above about format and network interoperation
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mean that hosting services such as Launchpad, Savannah, FedoraHosted,
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and Sourceforge could choose to run either the stable or beta versions.
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They might find it useful to run the beta version on their own beta
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Simultaneous Installation
246
-------------------------
248
Some people may want to simultaneously install and use both a stable
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release and development release.
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This can be handled in various ways either at the OS packaging or the
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Python level. We don't propose to directly address it in the upstream
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source. (For example, we will not change the breezy library name from one
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release to the next.)
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The issue already exists with people who may want to use for example the
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previous bzr release and the trunk. There is a related issue that plugins
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may be compatible with only some of the Bazaar versions people want to use
259
at the same time, and again that is something that can be handled
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OS distributors will be recommended to ship the bzr stable release that
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fits their schedule, the betas leading up to that release during their own
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beta period, and the bugfix releases following on from it. They might
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also choose to offer the beta releases as an alternative package.
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At present we have three upstream-maintained PPAs containing Ubuntu packages
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of Bazaar: ``bzr/daily`` (snapshots), ``bzr-beta-ppa/ppa`` (beta releases) and
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``bzr/ppa`` (ie stable). Beta contains the monthly beta releases, and the
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stable PPA contains stable releases and bugfixes to those releases.
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Some platforms with relatively less active packagers may choose to ship
281
only the stable releases. This is probably better than having them only
282
intermittently or slowly ship the monthly releases.
284
Binary installers should use a version number like '2.0.0-1' or
285
'2.0.0beta1-1' so that the last component just reflects the packaging
286
version, and can be incremented if a new installer is made with no
287
upstream source changes.
290
Code Freeze vs Announcement
291
---------------------------
293
We will separate the code freeze for a particular release from its actual
294
announcement, allowing a window of approximately one week for plugins to
295
be released and binary installers to be built. On the date the
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announcement is published, people will be able to easily install it.
299
Weekly Metronome Mail
300
---------------------
302
Every week the release manager should send a mail to the Bazaar list
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covering these points (as appropriate):
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* Early communication about changing dependencies or defaults
307
* Reminder re lifecycle and where we're up to right now, in particular the
308
dates for the next release and/or candidate.
310
* Summary of recent successes and pending work.
312
* Reminder re release objectives
314
* Reminder re things needing attention, e.g. bug triage, reviews, testing
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of certain things, etc.
321
Do users actually want this?
322
Apparently yes, because it's often requested and often raised as a
325
Would this confuse users?
326
It shouldn't, because it's a fairly standard scheme.
328
Won't it take more time to fix bugs in multiple places?
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It shouldn't, because we'll only do this when the stable bugfix seems
330
economical. When we fix bugs today in both trunk and release branches
331
it normally does not take much more time.
333
What about bzr in Ubuntu LTS, with a five-year support life?
334
Most bugs are either fixed within six months, or not fixed at all, or
335
not very important, or fixed as part of a large rework of the code
336
that would be too large to backport. However, if there are fixes that
337
are especially desired in an old release and feasible to do, we can do
338
them without making a general commitment.
340
Will anyone test the beta releases?
341
Probably yes, our most active users will run them, but if people would
342
really rather not test them, forcing them is not helpful.
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Isn't this a step backwards to a slower, less-agile process?
345
No, our trunk stays releasable, and we ship every month. We're just
346
cutting out things that hold us back (continuous rather than episodic
347
API stability; RCs every month) and giving users what they demand.
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How about calling the monthly releases "milestone" or "next" not "beta"?
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Those words are less scary but they also have less clear meanings.
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If this plan works, we'll expect to see the following changes. If they
357
don't occur, we'll think again:
359
* We see a distribution curve of users and bug reports across nightly, monthly
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and stable releases, indicating that each has value.
362
* API changes are easier or safer to make during beta periods, without
363
being held back by fears of compatibility or
365
* The stable releases are actually stable and don't introduce regressions
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* Many bugs are fixed in stable branches, without developers feeling this
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* Distributions ship the stable releases in their stable releases and the
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bugfix releases in their bugfix releases.
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* Plugin authors follow this policy, making their own bugfix releases.
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After doing this for the 2.0 cycle (September 2009 through to early
379
2010), it seems to be going well.
382
Reviewing for the Stable Branch
383
*******************************
385
These are guidelines and can be interpreted case-by-case.
387
* All changes to the stable branch should fix a bug, even if you would not
388
normally file a bug for the change. The bug description should if at
389
all possible explain how to manually verify the bug in a way that will
390
fail before and pass after the change. (These are requirements for the
393
* The change should be reasonably small and conservative.
395
* Remember that the patch will be read during the SRU
396
process and so keeping the patch small is useful even beyond keeping the
397
logical changes small. Avoid doing mechanical bulk changes on the
400
* Use particular care for things that may behave differently across
401
platforms, encodings or locales. It's harder to thoroughly test these
402
things before a release.
404
* Generally speaking, just cleaning things up is not a sufficient reason
405
to make changes to the stable branch. It has to actually fix a bug.
407
* Changes to the stable branch should include tests as usual.
409
* Don't change or remove existing APIs that might be used by plugins, even
410
if they are underscore-prefixed. Adding APIs that are also being added
411
to the trunk branch may make sense.
413
* Keeping consistency with trunk is useful, but less important than
414
keeping the stable branch stable.
416
* (more items welcome)
421
#. List thread "`[rfc] six-month stable release cycles`__", July 2009.
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.. __: https://lists.ubuntu.com/archives/bazaar/2009q3/060882.html
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doc/developers/cycle.txt
