5
:status: Current policy, as of 2009-08.
6
:blueprint: <https://blueprints.launchpad.net/bzr/+spec/6m-cycle>
9
Our users want easy access to bug fixes without other changes to the
10
core product. They also want a Just Works experience across the full
11
Bazaar ecosystem. To deliver the first and enable the second, we're
12
adopting some standard process patterns: a 6 monthly release cycle and a
13
stable branch. These changes will also have other benefits, including
14
better availability of bug fixes in OS distributions, more freedom to
15
remove old code, and less work for in packaging.
19
* `Bazaar Developer Document Catalog <index.html>`_
21
* `Releasing Bazaar <releasing.html>`_ -- the process for actually making
22
a release or release candidate.
27
Bazaar makes a release every month, preceded by a one-week
28
release-candidate test.
30
In any release we may fix bugs, add formats, change the default format,
31
improve performance, add new commands or change command line behaviour,
32
change the network protocol, or deprecate APIs. We sometimes also
33
introduce new bugs, regress existing behaviour or performance, remove
34
existing features or formats, or break behaviour or APIs depended upon by
35
plugins, external programs or users.
37
Some users are happy upgrading every month and consider the overall
38
positive balance of changes is worth some amount of churn. But there are
39
some serious problems:
41
* You cannot get bug fixes without also getting disruptive changes.
43
* Bazaar is seen as unstable.
45
* Many releases cause some plugin breakage.
47
* One month is not a very long window for dependent programs or systems
48
to catch up to changes in Bazaar before the release goes out of date.
50
* There's no clear indication to distributions which version they should
53
* If people (or their distributions) just pick an arbitrary version, they
54
may all be on different arbitrary versions, therefore they will have
55
different behaviour and different bugs, and sometimes interoperation
58
* Any effort we, or distributors, wanted to put into backporting fixes
59
would be dissipated across many possible backport target releases.
61
* When in the past we've tried either stalling releases for particular
62
features, or having trunk frozen for some weeks, it causes churn and
63
waste. People rush features in, or already landed features wait a long
64
time to be released, or branches go out of date because they cannot
71
Bazaar will make a major release every six months, which will be supported
72
at least until the time of the next major release. During this support
73
period, we'll make incremental releases which fix bugs, but which do not
74
change network or disk formats or command syntax, and which do not require
77
We will also run a development series, which will become the next major
78
release. We'll make a beta release from this every four weeks. The
79
beta releases will be as stable as our current monthly releases and
80
completely suitable for everyday use by users who can tolerate changes
83
Having the stable series isn't a reason to cut back on QA or to make the
84
trunk or development releases unstable, which would only make our job
85
harder. We keep our trunk in an always-releasable state, and that should
86
continue: any beta release could potentially be supported in the long
87
term, but we identify particular releases that actually will be supported.
89
The trunk will never be frozen: changes that pass review, other quality
90
checks and that are agreed amongst the developers can always be landed
91
into trunk. The only restrictions will be on branches specifically
92
targeted at a release.
100
2.0.0 --- 2.0.1 -- 2.0.2 -- ...
102
+--2.1.0beta1 -- 2.1.0beta2 -- ... -- 2.1.0rc1 -- 2.1.0 -- 2.1.1 -- ...
108
Starting from the date of a major release:
110
At four-week intervals we make a new beta release. There will be no
111
separate release candidate, but if a serious problem is discovered we may
112
do the next beta ahead of schedule or make a point release. There will be
113
about five or six releases in that series.
115
In parallel with this, bugs targeted to the previous major release are
116
merged into its branch. We will make bugfix releases from that branch as
117
appropriate to the accumulation of changes, perhaps monthly, perhaps more
118
often if there are serious bugs, perhaps much less often if no new changes
121
We will then make a release candidate for the next major release, and at
122
this point create a release branch for it. We will iterate release
123
candidates at approximately weekly intervals until there are no bugs
124
blocking the final major release.
126
Compared to the current process this has approximately the same amount of
127
release-related work, because the extra releases from the stable branch
128
are "paid for" by not doing RCs for the development series.
130
We will synchronize our major releases with Ubuntu, so that they come out
131
in sufficient time for some testing and margin of error before Ubuntu's
138
We value regular releases. We prefer to slip a feature or fix to
139
a later release rather than to make a release late. We will normally only
140
slip a release to fix a critical bug.
146
The number for a six-month cycle is chosen at the start, with an increment
147
to either the first field (3.0.0) or second field (3.1.0) depending on
148
what we expect to be the user impact of the release. We expect releases
149
that culminate in a new disk format or that require changes in how people
150
use the tool will get a new major number. We can change (forward only) if
151
it turns out that we land larger changes than were expected.
153
We will always use the 3-digit form (major.minor.micro) even when
154
referring to the initial major release. This should help clarify where a
155
patch is intended to land. (eg, "I propose this for 2.0.0" is clear, while
156
"I propose this for 2.0" could mean you want to make the 2.0.0 release, or
157
that you just want to land on the 2.0.x stable release series.)
163
Major releases (2.0.0 or 2.1.0)
164
The big ones, every six months, intended to ship in distributions and
165
to be used by stability-oriented users.
167
Release candidate (2.0.0rc1)
168
A preview of a major release, made one or a few weeks beforehand at
169
the time the release branch is created. There should be few if any
170
changes from the rc to the stable release. We should avoid the
171
confusing phrasing "release candidate 2.0.0rc1 is released"; instead
174
Bugfix releases (2.0.1)
175
Based on the previous major release or bugfix; contains only bugfixes
176
and perhaps documentation or translation corrections.
179
A major release and its descendant bugfix releases.
182
Either a major release or a bugfix release.
184
Beta release (3.0.0beta1)
185
Made from trunk every month, except for the month there's a major
186
release. Stable and suitable for users who want the latest code and
187
can live with some changes from month to month.
190
The development releases leading up to a stable release.
195
Bug fixes should normally be done first against the stable branch,
196
reviewed against that branch, and then merged forward to trunk.
198
It may not always be easy to do this, if fixing the bug requires large
199
changes or the affected code is different in the stable and development
200
branches. If the tradeoff does not seem worthwhile the bug can be fixed
201
only in the development branch, at least in the first instance. If users
202
later want the fix backported we can discuss it.
204
Developers can merge the release branch into trunk as often as they like,
205
only asking for review if they're making nontrivial changes or feel review
209
Feature and Performance Work
210
----------------------------
212
Features can be landed to the development branch at any time, and they'll
213
be released for testing within a month.
215
Performance bugs, although important, will generally not be landed in a
216
stable series. Fixing performance bugs well often requires nontrivial
217
code changes or new formats. These are not suitable for a stable series.
219
Performance bugs that can be fixed with a small safe patch can be
220
considered for the stable series.
226
Plugins that want to cooperate with this should make a series and a branch
227
that matches each bzr stable series, and follow similar rules in making
228
releases from their stable branch. We'd expect that plugins will make a
229
release between the last development release of a series and the major
232
Within a stable series, anything that breaks any known plugin is
233
considered an API break and will be avoided. Before
234
making each bugfix release, we'll test that code against important
237
Within a development series, the focus is on helping plugin authors keep
238
up to date by giving clear error messages when an interface is removed.
239
We will no longer focus on letting old plugin code work with new versions
240
of bzrlib, which is an elusive target in Python.
242
This may mean that in cases where today a plugin would keep running but
243
give warnings, it will now fail altogether with an error.
245
In return we expect more freedom to change and cleanup bzrlib code without
246
needing to keep old code around, or write extra compatibility shims, or
247
have review turnarounds related to compatibility. Some changes, such as
248
removing module-global variables, that are hard to do now, will be
249
possible to do safely.
251
Discussion of plugins here includes programs that import and use bzrlib
252
but that aren't technically plugins. The same approach, though the
253
technical considerations are different, should apply to other extensions
254
such as programs that use bzr through the shell interface.
258
Data and Network Formats
259
------------------------
261
Any development release should be able to interoperate with the previous
262
stable release, and any stable release should be able to interoperate with
263
the previous stable release. This is a minimum and normally releases will be
264
able to interoperate with all previous releases as at present.
266
Each major release will have one recommended data format which will be the
267
default. The name of the format will indicate which release series (not
268
specific release) it comes from: '2a' is the first supported format for
269
the 2.0.x series, '2b' the second, etc. We don't mention the particular
270
release that introduced it so as to avoid problems predicting precisely
273
During a development series we may have a series of experimental formats.
274
We will not leave people stranded if they test these formats, but we also
275
won't guarantee to keep supporting them in a future release. If something
276
inserted in one development release turns out to be bad it can just be
283
The guarantees made above about format and network interoperation
284
mean that hosting services such as Launchpad, Savannah, FedoraHosted,
285
and Sourceforge could choose to run either the stable or beta versions.
286
They might find it useful to run the beta version on their own beta
290
Simultaneous Installation
291
-------------------------
293
Some people may want to simultaneously install and use both a stable
294
release and development release.
296
This can be handled in various ways either at the OS packaging or the
297
Python level. We don't propose to directly address it in the upstream
298
source. (For example, we will not change the bzrlib library name from one
299
release to the next.)
301
The issue already exists with people who may want to use for example the
302
previous bzr release and the trunk. There is a related issue that plugins
303
may be compatible with only some of the Bazaar versions people want to use
304
at the same time, and again that is something that can be handled
311
OS distributors will be recommended to ship the bzr stable release that
312
fits their schedule, the betas leading up to that release during their own
313
beta period, and the bugfix releases following on from it. They might
314
also choose to offer the beta releases as an alternative package.
320
At present we have three upstream-maintained PPAs containing Ubuntu
321
packages of Bazaar: ``~bzr-nightly-ppa``, ``~bzr-beta-ppa`` (rcs and
322
releases) and ``~bzr`` (ie stable). We will keep these PPAs, and reorient
323
beta to contain the monthly beta releases, and the stable PPA to contain
324
stable releases, their release candidates, and bugfixes to those releases.
326
Some platforms with relatively less active packagers may choose to ship
327
only the stable releases. This is probably better than having them only
328
intermittently or slowly ship the monthly releases.
330
Binary installers should use a version number like '2.0.0-1' or
331
'2.0.0beta1-1' so that the last component just reflects the packaging
332
version, and can be incremented if a new installer is made with no
333
upstream source changes.
336
Code Freeze vs Announcement
337
---------------------------
339
We will separate the code freeze for a particular release from its actual
340
announcement, allowing a window of approximately one week for plugins to
341
be released and binary installers to be built. On the date the
342
announcement is published, people will be able to easily install it.
345
Weekly Metronome Mail
346
---------------------
348
Every week the release manager should send a mail to the Bazaar list
349
covering these points (as appropriate):
351
* Early communication about changing dependencies or defaults
353
* Reminder re lifecycle and where we're up to right now, in particular the
354
dates for the next release and/or candidate.
356
* Summary of recent successes and pending work.
358
* Reminder re release objectives
360
* Reminder re things needing attention, e.g. bug triage, reviews, testing
361
of certain things, etc.
367
Do users actually want this?
368
Apparently yes, because it's often requested and often raised as a
371
Would this confuse users?
372
It shouldn't, because it's a fairly standard scheme.
374
Won't it take more time to fix bugs in multiple places?
375
It shouldn't, because we'll only do this when the stable bugfix seems
376
economical. When we fix bugs today in both trunk and release branches
377
it normally does not take much more time.
379
What about bzr in Ubuntu LTS, with a five-year support life?
380
Most bugs are either fixed within six months, or not fixed at all, or
381
not very important, or fixed as part of a large rework of the code
382
that would be too large to backport. However, if there are fixes that
383
are especially desired in an old release and feasible to do, we can do
384
them without making a general commitment.
386
Will anyone test the beta releases?
387
Probably yes, our most active users will run them, but if people would
388
really rather not test them, forcing them is not helpful.
390
Isn't this a step backwards to a slower, less-agile process?
391
No, our trunk stays releasable, and we ship every month. We're just
392
cutting out things that hold us back (continuous rather than episodic
393
API stability; RCs every month) and giving users what they demand.
395
How about calling the monthly releases "milestone" or "next" not "beta"?
396
Those words are less scary but they also have less clear meanings.
402
If this plan works, we'll expect to see the following changes. If they
403
don't occur, we'll think again:
405
* We see a distribution curve of users and bug reports across nightly, monthly
406
and stable releases, indicating that each has value.
408
* API changes are easier or safer to make during beta periods, without
409
being held back by fears of compatibility or
411
* The stable releases are actually stable and don't introduce regressions
414
* Many bugs are fixed in stable branches, without developers feeling this
417
* Distributions ship the stable releases in their stable releases and the
418
bugfix releases in their bugfix releases.
420
* Plugin authors follow this policy, making their own bugfix releases.
427
#. List thread "[rfc] six-month stable release cycles", July 2009.
430
vim: filetype=rst textwidth=74 ai shiftwidth=4
added
removed
doc/developers/cycle.txt
