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.
28
Bazaar will make a major release every six months, which will be supported
29
at least until the time of the next major release. During this support
30
period, we'll make incremental releases which fix bugs, but which do not
31
change network or disk formats or command syntax, and which do not require
34
We will also run a development series, which will become the next major
35
release. We'll make a beta release from this every four weeks. The
36
beta releases will be as stable as our current monthly releases and
37
completely suitable for everyday use by users who can tolerate changes
40
Having the stable series isn't a reason to cut back on QA or to make the
41
trunk or development releases unstable, which would only make our job
42
harder. We keep our trunk in an always-releasable state, and that should
43
continue: any beta release could potentially be supported in the long
44
term, but we identify particular releases that actually will be supported.
46
The trunk will never be frozen: changes that pass review, other quality
47
checks and that are agreed amongst the developers can always be landed
48
into trunk. The only restrictions will be on branches specifically
49
targeted at a release.
57
2.0.0 --- 2.0.1 -- 2.0.2 -- ...
59
+--2.1.0beta1 -- 2.1.0beta2 -- ... -- 2.1.0rc1 -- 2.1.0 -- 2.1.1 -- ...
65
Starting from the date of a major release:
67
At four-week intervals we make a new beta release. There will be no
68
separate release candidate, but if a serious problem is discovered we may
69
do the next beta ahead of schedule or make a point release. There will be
70
about five or six releases in that series.
72
In parallel with this, bugs targeted to the previous major release are
73
merged into its branch. We will make bugfix releases from that branch as
74
appropriate to the accumulation of changes, perhaps monthly, perhaps more
75
often if there are serious bugs, perhaps much less often if no new changes
78
We will then make a release candidate for the next major release, and at
79
this point create a release branch for it. We will iterate release
80
candidates at approximately weekly intervals until there are no bugs
81
blocking the final major release.
83
Compared to the current process this has approximately the same amount of
84
release-related work, because the extra releases from the stable branch
85
are "paid for" by not doing RCs for the development series.
87
We will synchronize our major releases with Ubuntu, so that they come out
88
in sufficient time for some testing and margin of error before Ubuntu's
95
We value regular releases. We prefer to slip a feature or fix to
96
a later release rather than to make a release late. We will normally only
97
slip a release to fix a critical bug.
103
The number for a six-month cycle is chosen at the start, with an increment
104
to either the first field (3.0.0) or second field (3.1.0) depending on
105
what we expect to be the user impact of the release. We expect releases
106
that culminate in a new disk format or that require changes in how people
107
use the tool will get a new major number. We can change (forward only) if
108
it turns out that we land larger changes than were expected.
110
We will always use the 3-digit form (major.minor.micro) even when
111
referring to the initial major release. This should help clarify where a
112
patch is intended to land. (eg, "I propose this for 2.0.0" is clear, while
113
"I propose this for 2.0" could mean you want to make the 2.0.0 release, or
114
that you just want to land on the 2.0.x stable release series.)
120
Major releases (2.0.0 or 2.1.0)
121
The big ones, every six months, intended to ship in distributions and
122
to be used by stability-oriented users.
124
Release candidate (2.0.0rc1)
125
A preview of a major release, made one or a few weeks beforehand at
126
the time the release branch is created. There should be few if any
127
changes from the rc to the stable release. We should avoid the
128
confusing phrasing "release candidate 2.0.0rc1 is released"; instead
131
Bugfix releases (2.0.1)
132
Based on the previous major release or bugfix; contains only bugfixes
133
and perhaps documentation or translation corrections.
136
A major release and its descendant bugfix releases.
139
Either a major release or a bugfix release.
141
Beta release (3.0.0beta1)
142
Made from trunk every month, except for the month there's a major
143
release. Stable and suitable for users who want the latest code and
144
can live with some changes from month to month.
147
The development releases leading up to a stable release.
152
Bug fixes should normally be done first against the stable branch,
153
reviewed against that branch, and then merged forward to trunk.
155
It may not always be easy to do this, if fixing the bug requires large
156
changes or the affected code is different in the stable and development
157
branches. If the tradeoff does not seem worthwhile the bug can be fixed
158
only in the development branch, at least in the first instance. If users
159
later want the fix backported we can discuss it.
161
Developers can merge the release branch into trunk as often as they like,
162
only asking for review if they're making nontrivial changes or feel review
166
Feature and Performance Work
167
----------------------------
169
Features can be landed to the development branch at any time, and they'll
170
be released for testing within a month.
172
Performance bugs, although important, will generally not be landed in a
173
stable series. Fixing performance bugs well often requires nontrivial
174
code changes or new formats. These are not suitable for a stable series.
176
Performance bugs that can be fixed with a small safe patch can be
177
considered for the stable series.
183
Plugins that want to cooperate with this should make a series and a branch
184
that matches each bzr stable series, and follow similar rules in making
185
releases from their stable branch. We'd expect that plugins will make a
186
release between the last development release of a series and the major
189
Within a stable series, anything that breaks any known plugin is
190
considered an API break and will be avoided. Before
191
making each bugfix release, we'll test that code against important
194
Within a development series, the focus is on helping plugin authors keep
195
up to date by giving clear error messages when an interface is removed.
196
We will no longer focus on letting old plugin code work with new versions
197
of bzrlib, which is an elusive target in Python.
199
This may mean that in cases where today a plugin would keep running but
200
give warnings, it will now fail altogether with an error.
202
In return we expect more freedom to change and cleanup bzrlib code without
203
needing to keep old code around, or write extra compatibility shims, or
204
have review turnarounds related to compatibility. Some changes, such as
205
removing module-global variables, that are hard to do now, will be
206
possible to do safely.
208
Discussion of plugins here includes programs that import and use bzrlib
209
but that aren't technically plugins. The same approach, though the
210
technical considerations are different, should apply to other extensions
211
such as programs that use bzr through the shell interface.
215
Data and Network Formats
216
------------------------
218
Any development release should be able to interoperate with the previous
219
stable release, and any stable release should be able to interoperate with
220
the previous stable release. This is a minimum and normally releases will be
221
able to interoperate with all previous releases as at present.
223
Each major release will have one recommended data format which will be the
224
default. The name of the format will indicate which release series (not
225
specific release) it comes from: '2a' is the first supported format for
226
the 2.0.x series, '2b' the second, etc. We don't mention the particular
227
release that introduced it so as to avoid problems predicting precisely
230
During a development series we may have a series of experimental formats.
231
We will not leave people stranded if they test these formats, but we also
232
won't guarantee to keep supporting them in a future release. If something
233
inserted in one development release turns out to be bad it can just be
240
The guarantees made above about format and network interoperation
241
mean that hosting services such as Launchpad, Savannah, FedoraHosted,
242
and Sourceforge could choose to run either the stable or beta versions.
243
They might find it useful to run the beta version on their own beta
247
Simultaneous Installation
248
-------------------------
250
Some people may want to simultaneously install and use both a stable
251
release and development release.
253
This can be handled in various ways either at the OS packaging or the
254
Python level. We don't propose to directly address it in the upstream
255
source. (For example, we will not change the bzrlib library name from one
256
release to the next.)
258
The issue already exists with people who may want to use for example the
259
previous bzr release and the trunk. There is a related issue that plugins
260
may be compatible with only some of the Bazaar versions people want to use
261
at the same time, and again that is something that can be handled
268
OS distributors will be recommended to ship the bzr stable release that
269
fits their schedule, the betas leading up to that release during their own
270
beta period, and the bugfix releases following on from it. They might
271
also choose to offer the beta releases as an alternative package.
277
At present we have three upstream-maintained PPAs containing Ubuntu
278
packages of Bazaar: ``~bzr-nightly-ppa``, ``~bzr-beta-ppa`` (rcs and
279
releases) and ``~bzr`` (ie stable). We will keep these PPAs, and reorient
280
beta to contain the monthly beta releases, and the stable PPA to contain
281
stable releases, their release candidates, and bugfixes to those releases.
283
Some platforms with relatively less active packagers may choose to ship
284
only the stable releases. This is probably better than having them only
285
intermittently or slowly ship the monthly releases.
287
Binary installers should use a version number like '2.0.0-1' or
288
'2.0.0beta1-1' so that the last component just reflects the packaging
289
version, and can be incremented if a new installer is made with no
290
upstream source changes.
293
Code Freeze vs Announcement
294
---------------------------
296
We will separate the code freeze for a particular release from its actual
297
announcement, allowing a window of approximately one week for plugins to
298
be released and binary installers to be built. On the date the
299
announcement is published, people will be able to easily install it.
1
The Bazaar Development Cycle
2
============================
9
We normally have one person acting as the release manager, who
10
organizes development for the release and also actually makes the release
11
tarball and posts announcements. It can be a different person from one
14
Our usual process is that one week before release we will make a release
15
branch from the trunk. We do one commit to that branch to change the
16
version number to 'rc1', and advance the trunk version to 'dev' for the
19
We then publish and announce this release candidate according to the
20
process below. We then have a week of general testing of the rc,
21
including some time for plugin authors to update their code for any
24
Normally no changes will be made on the release branch unless serious bugs
25
or regressions are found, and the release manager decides they should be
26
merged in. After one week, the release branch's version number is updated
27
and it's published as the final release. If regressions or serious
28
problems are discovered after the final release we may make an additional
29
point release from that branch.
31
The process or timing can vary if that seems appropriate in a particular
32
case but we try to release on a regular four week cycle.
34
The net effect is that the code gets some extra testing before release,
35
and the trunk is always open for general development.
41
To start a new release cycle:
43
#. Send mail to the list with the key dates, who will be the release
44
manager, and the main themes or targetted bugs. Ask people to nominate
45
objectives, or point out any high-risk things that are best done early,
46
or that interact with other changes.
48
#. Add a new "series" in Launchpad at <https://launchpad.net/bzr/+addseries>.
49
There is one series for every *x.y* release.
51
#. Add milestones to that series for the release candidate and the final
52
release, and their expected dates.
54
#. Deactivate old releases and their milestones.
56
#. Update the version number in the ``bzr`` script, and the
57
``bzrlib/__init__.py`` file.
302
60
Weekly Metronome Mail
318
76
of certain things, etc.
324
Do users actually want this?
325
Apparently yes, because it's often requested and often raised as a
328
Would this confuse users?
329
It shouldn't, because it's a fairly standard scheme.
331
Won't it take more time to fix bugs in multiple places?
332
It shouldn't, because we'll only do this when the stable bugfix seems
333
economical. When we fix bugs today in both trunk and release branches
334
it normally does not take much more time.
336
What about bzr in Ubuntu LTS, with a five-year support life?
337
Most bugs are either fixed within six months, or not fixed at all, or
338
not very important, or fixed as part of a large rework of the code
339
that would be too large to backport. However, if there are fixes that
340
are especially desired in an old release and feasible to do, we can do
341
them without making a general commitment.
343
Will anyone test the beta releases?
344
Probably yes, our most active users will run them, but if people would
345
really rather not test them, forcing them is not helpful.
347
Isn't this a step backwards to a slower, less-agile process?
348
No, our trunk stays releasable, and we ship every month. We're just
349
cutting out things that hold us back (continuous rather than episodic
350
API stability; RCs every month) and giving users what they demand.
352
How about calling the monthly releases "milestone" or "next" not "beta"?
353
Those words are less scary but they also have less clear meanings.
359
If this plan works, we'll expect to see the following changes. If they
360
don't occur, we'll think again:
362
* We see a distribution curve of users and bug reports across nightly, monthly
363
and stable releases, indicating that each has value.
365
* API changes are easier or safer to make during beta periods, without
366
being held back by fears of compatibility or
368
* The stable releases are actually stable and don't introduce regressions
371
* Many bugs are fixed in stable branches, without developers feeling this
374
* Distributions ship the stable releases in their stable releases and the
375
bugfix releases in their bugfix releases.
377
* Plugin authors follow this policy, making their own bugfix releases.
381
After doing this for the 2.0 cycle (September 2009 through to early
382
2010), it seems to be going well.
385
Reviewing for the Stable Branch
386
*******************************
388
These are guidelines and can be interpreted case-by-case.
390
* All changes to the stable branch should fix a bug, even if you would not
391
normally file a bug for the change. The bug description should if at
392
all possible explain how to manually verify the bug in a way that will
393
fail before and pass after the change. (These are requirements for the
396
* The change should be reasonably small and conservative.
398
* Remember that the patch will be read during the SRU
399
process and so keeping the patch small is useful even beyond keeping the
400
logical changes small. Avoid doing mechanical bulk changes on the
403
* Use particular care for things that may behave differently across
404
platforms, encodings or locales. It's harder to thoroughly test these
405
things before a release.
407
* Generally speaking, just cleaning things up is not a sufficient reason
408
to make changes to the stable branch. It has to actually fix a bug.
410
* Changes to the stable branch should include tests as usual.
412
* Don't change or remove existing APIs that might be used by plugins, even
413
if they are underscore-prefixed. Adding APIs that are also being added
414
to the trunk branch may make sense.
416
* Keeping consistency with trunk is useful, but less important than
417
keeping the stable branch stable.
419
* (more items welcome)
424
#. List thread "`[rfc] six-month stable release cycles`__", July 2009.
426
.. __: https://lists.ubuntu.com/archives/bazaar/2009q3/060882.html
79
Starting the release phase
80
--------------------------
82
When it's time to make the release candidate:
84
#. We create a new pqm-controlled branch for this release series. The
85
branch must be created by Robert Collins on the pqm server.
86
This branch means that from the first release candidate onwards,
87
general development continues on the trunk, and only
88
specifically-targetted fixes go into the release.
90
#. Register the branch at <https://launchpad.net/products/bzr/+addbranch>
92
#. The revision at the start of that branch is `released
93
<releasing.html>`_ as the first RC.
99
* `Bazaar Developer Document Catalog <index.html>`_
101
* `Releasing Bazaar <releasing.html>`_ -- the process for actually making
102
a release or release candidate.
429
106
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