1GITWORKFLOWS(7)                   Git Manual                   GITWORKFLOWS(7)


6       gitworkflows - An overview of recommended workflows with Git


9       git *


13       This document attempts to write down and motivate some of the workflow
14       elements used for git.git itself. Many ideas apply in general, though
15       the full workflow is rarely required for smaller projects with fewer
16       people involved.
18       We formulate a set of rules for quick reference, while the prose tries
19       to motivate each of them. Do not always take them literally; you should
20       value good reasons for your actions higher than manpages such as this
21       one.


24       As a general rule, you should try to split your changes into small
25       logical steps, and commit each of them. They should be consistent,
26       working independently of any later commits, pass the test suite, etc.
27       This makes the review process much easier, and the history much more
28       useful for later inspection and analysis, for example with git-blame(1)
29       and git-bisect(1).
31       To achieve this, try to split your work into small steps from the very
32       beginning. It is always easier to squash a few commits together than to
33       split one big commit into several. Don’t be afraid of making too small
34       or imperfect steps along the way. You can always go back later and edit
35       the commits with git rebase --interactive before you publish them. You
36       can use git stash push --keep-index to run the test suite independent
37       of other uncommitted changes; see the EXAMPLES section of git-stash(1).


40       There are two main tools that can be used to include changes from one
41       branch on another: git-merge(1) and git-cherry-pick(1).
43       Merges have many advantages, so we try to solve as many problems as
44       possible with merges alone. Cherry-picking is still occasionally
45       useful; see "Merging upwards" below for an example.
47       Most importantly, merging works at the branch level, while
48       cherry-picking works at the commit level. This means that a merge can
49       carry over the changes from 1, 10, or 1000 commits with equal ease,
50       which in turn means the workflow scales much better to a large number
51       of contributors (and contributions). Merges are also easier to
52       understand because a merge commit is a "promise" that all changes from
53       all its parents are now included.
55       There is a tradeoff of course: merges require a more careful branch
56       management. The following subsections discuss the important points.
58   Graduation
59       As a given feature goes from experimental to stable, it also
60       "graduates" between the corresponding branches of the software. git.git
61       uses the following integration branches:
63       ·   maint tracks the commits that should go into the next "maintenance
64           release", i.e., update of the last released stable version;
66       ·   master tracks the commits that should go into the next release;
68       ·   next is intended as a testing branch for topics being tested for
69           stability for master.
71       There is a fourth official branch that is used slightly differently:
73       ·   pu (proposed updates) is an integration branch for things that are
74           not quite ready for inclusion yet (see "Integration Branches"
75           below).
77       Each of the four branches is usually a direct descendant of the one
78       above it.
80       Conceptually, the feature enters at an unstable branch (usually next or
81       pu), and "graduates" to master for the next release once it is
82       considered stable enough.
84   Merging upwards
85       The "downwards graduation" discussed above cannot be done by actually
86       merging downwards, however, since that would merge all changes on the
87       unstable branch into the stable one. Hence the following:
89       Example 1. Merge upwards
91       Always commit your fixes to the oldest supported branch that requires
92       them. Then (periodically) merge the integration branches upwards into
93       each other.
95       This gives a very controlled flow of fixes. If you notice that you have
96       applied a fix to e.g. master that is also required in maint, you will
97       need to cherry-pick it (using git-cherry-pick(1)) downwards. This will
98       happen a few times and is nothing to worry about unless you do it very
99       frequently.
101   Topic branches
102       Any nontrivial feature will require several patches to implement, and
103       may get extra bugfixes or improvements during its lifetime.
105       Committing everything directly on the integration branches leads to
106       many problems: Bad commits cannot be undone, so they must be reverted
107       one by one, which creates confusing histories and further error
108       potential when you forget to revert part of a group of changes. Working
109       in parallel mixes up the changes, creating further confusion.
111       Use of "topic branches" solves these problems. The name is pretty self
112       explanatory, with a caveat that comes from the "merge upwards" rule
113       above:
115       Example 2. Topic branches
117       Make a side branch for every topic (feature, bugfix, ...). Fork it off
118       at the oldest integration branch that you will eventually want to merge
119       it into.
121       Many things can then be done very naturally:
123       ·   To get the feature/bugfix into an integration branch, simply merge
124           it. If the topic has evolved further in the meantime, merge again.
125           (Note that you do not necessarily have to merge it to the oldest
126           integration branch first. For example, you can first merge a bugfix
127           to next, give it some testing time, and merge to maint when you
128           know it is stable.)
130       ·   If you find you need new features from the branch other to continue
131           working on your topic, merge other to topic. (However, do not do
132           this "just habitually", see below.)
134       ·   If you find you forked off the wrong branch and want to move it
135           "back in time", use git-rebase(1).
137       Note that the last point clashes with the other two: a topic that has
138       been merged elsewhere should not be rebased. See the section on
139       RECOVERING FROM UPSTREAM REBASE in git-rebase(1).
141       We should point out that "habitually" (regularly for no real reason)
142       merging an integration branch into your topics — and by extension,
143       merging anything upstream into anything downstream on a regular basis —
144       is frowned upon:
146       Example 3. Merge to downstream only at well-defined points
148       Do not merge to downstream except with a good reason: upstream API
149       changes affect your branch; your branch no longer merges to upstream
150       cleanly; etc.
152       Otherwise, the topic that was merged to suddenly contains more than a
153       single (well-separated) change. The many resulting small merges will
154       greatly clutter up history. Anyone who later investigates the history
155       of a file will have to find out whether that merge affected the topic
156       in development. An upstream might even inadvertently be merged into a
157       "more stable" branch. And so on.
159   Throw-away integration
160       If you followed the last paragraph, you will now have many small topic
161       branches, and occasionally wonder how they interact. Perhaps the result
162       of merging them does not even work? But on the other hand, we want to
163       avoid merging them anywhere "stable" because such merges cannot easily
164       be undone.
166       The solution, of course, is to make a merge that we can undo: merge
167       into a throw-away branch.
169       Example 4. Throw-away integration branches
171       To test the interaction of several topics, merge them into a throw-away
172       branch. You must never base any work on such a branch!
174       If you make it (very) clear that this branch is going to be deleted
175       right after the testing, you can even publish this branch, for example
176       to give the testers a chance to work with it, or other developers a
177       chance to see if their in-progress work will be compatible. git.git has
178       such an official throw-away integration branch called pu.
180   Branch management for a release
181       Assuming you are using the merge approach discussed above, when you are
182       releasing your project you will need to do some additional branch
183       management work.
185       A feature release is created from the master branch, since master
186       tracks the commits that should go into the next feature release.
188       The master branch is supposed to be a superset of maint. If this
189       condition does not hold, then maint contains some commits that are not
190       included on master. The fixes represented by those commits will
191       therefore not be included in your feature release.
193       To verify that master is indeed a superset of maint, use git log:
195       Example 5. Verify master is a superset of maint
197       git log master..maint
199       This command should not list any commits. Otherwise, check out master
200       and merge maint into it.
202       Now you can proceed with the creation of the feature release. Apply a
203       tag to the tip of master indicating the release version:
205       Example 6. Release tagging
207       git tag -s -m "Git X.Y.Z" vX.Y.Z master
209       You need to push the new tag to a public Git server (see "DISTRIBUTED
210       WORKFLOWS" below). This makes the tag available to others tracking your
211       project. The push could also trigger a post-update hook to perform
212       release-related items such as building release tarballs and
213       preformatted documentation pages.
215       Similarly, for a maintenance release, maint is tracking the commits to
216       be released. Therefore, in the steps above simply tag and push maint
217       rather than master.
219   Maintenance branch management after a feature release
220       After a feature release, you need to manage your maintenance branches.
222       First, if you wish to continue to release maintenance fixes for the
223       feature release made before the recent one, then you must create
224       another branch to track commits for that previous release.
226       To do this, the current maintenance branch is copied to another branch
227       named with the previous release version number (e.g. maint-X.Y.(Z-1)
228       where X.Y.Z is the current release).
230       Example 7. Copy maint
232       git branch maint-X.Y.(Z-1) maint
234       The maint branch should now be fast-forwarded to the newly released
235       code so that maintenance fixes can be tracked for the current release:
237       Example 8. Update maint to new release
239       ·   git checkout maint
241       ·   git merge --ff-only master
243       If the merge fails because it is not a fast-forward, then it is
244       possible some fixes on maint were missed in the feature release. This
245       will not happen if the content of the branches was verified as
246       described in the previous section.
248   Branch management for next and pu after a feature release
249       After a feature release, the integration branch next may optionally be
250       rewound and rebuilt from the tip of master using the surviving topics
251       on next:
253       Example 9. Rewind and rebuild next
255       ·   git checkout next
257       ·   git reset --hard master
259       ·   git merge ai/topic_in_next1
261       ·   git merge ai/topic_in_next2
263       ·   ...
265       The advantage of doing this is that the history of next will be clean.
266       For example, some topics merged into next may have initially looked
267       promising, but were later found to be undesirable or premature. In such
268       a case, the topic is reverted out of next but the fact remains in the
269       history that it was once merged and reverted. By recreating next, you
270       give another incarnation of such topics a clean slate to retry, and a
271       feature release is a good point in history to do so.
273       If you do this, then you should make a public announcement indicating
274       that next was rewound and rebuilt.
276       The same rewind and rebuild process may be followed for pu. A public
277       announcement is not necessary since pu is a throw-away branch, as
278       described above.


281       After the last section, you should know how to manage topics. In
282       general, you will not be the only person working on the project, so you
283       will have to share your work.
285       Roughly speaking, there are two important workflows: merge and patch.
286       The important difference is that the merge workflow can propagate full
287       history, including merges, while patches cannot. Both workflows can be
288       used in parallel: in git.git, only subsystem maintainers use the merge
289       workflow, while everyone else sends patches.
291       Note that the maintainer(s) may impose restrictions, such as
292       "Signed-off-by" requirements, that all commits/patches submitted for
293       inclusion must adhere to. Consult your project’s documentation for more
294       information.
296   Merge workflow
297       The merge workflow works by copying branches between upstream and
298       downstream. Upstream can merge contributions into the official history;
299       downstream base their work on the official history.
301       There are three main tools that can be used for this:
303       ·   git-push(1) copies your branches to a remote repository, usually to
304           one that can be read by all involved parties;
306       ·   git-fetch(1) that copies remote branches to your repository; and
308       ·   git-pull(1) that does fetch and merge in one go.
310       Note the last point. Do not use git pull unless you actually want to
311       merge the remote branch.
313       Getting changes out is easy:
315       Example 10. Push/pull: Publishing branches/topics
317       git push <remote> <branch> and tell everyone where they can fetch from.
319       You will still have to tell people by other means, such as mail. (Git
320       provides the git-request-pull(1) to send preformatted pull requests to
321       upstream maintainers to simplify this task.)
323       If you just want to get the newest copies of the integration branches,
324       staying up to date is easy too:
326       Example 11. Push/pull: Staying up to date
328       Use git fetch <remote> or git remote update to stay up to date.
330       Then simply fork your topic branches from the stable remotes as
331       explained earlier.
333       If you are a maintainer and would like to merge other people’s topic
334       branches to the integration branches, they will typically send a
335       request to do so by mail. Such a request looks like
337           Please pull from
338               <url> <branch>
341       In that case, git pull can do the fetch and merge in one go, as
342       follows.
344       Example 12. Push/pull: Merging remote topics
346       git pull <url> <branch>
348       Occasionally, the maintainer may get merge conflicts when they try to
349       pull changes from downstream. In this case, they can ask downstream to
350       do the merge and resolve the conflicts themselves (perhaps they will
351       know better how to resolve them). It is one of the rare cases where
352       downstream should merge from upstream.
354   Patch workflow
355       If you are a contributor that sends changes upstream in the form of
356       emails, you should use topic branches as usual (see above). Then use
357       git-format-patch(1) to generate the corresponding emails (highly
358       recommended over manually formatting them because it makes the
359       maintainer’s life easier).
361       Example 13. format-patch/am: Publishing branches/topics
363       ·   git format-patch -M upstream..topic to turn them into preformatted
364           patch files
366       ·   git send-email --to=<recipient> <patches>
368       See the git-format-patch(1) and git-send-email(1) manpages for further
369       usage notes.
371       If the maintainer tells you that your patch no longer applies to the
372       current upstream, you will have to rebase your topic (you cannot use a
373       merge because you cannot format-patch merges):
375       Example 14. format-patch/am: Keeping topics up to date
377       git pull --rebase <url> <branch>
379       You can then fix the conflicts during the rebase. Presumably you have
380       not published your topic other than by mail, so rebasing it is not a
381       problem.
383       If you receive such a patch series (as maintainer, or perhaps as a
384       reader of the mailing list it was sent to), save the mails to files,
385       create a new topic branch and use git am to import the commits:
387       Example 15. format-patch/am: Importing patches
389       git am < patch
391       One feature worth pointing out is the three-way merge, which can help
392       if you get conflicts: git am -3 will use index information contained in
393       patches to figure out the merge base. See git-am(1) for other options.


396       gittutorial(7), git-push(1), git-pull(1), git-merge(1), git-rebase(1),
397       git-format-patch(1), git-send-email(1), git-am(1)


400       Part of the git(1) suite
404Git 2.18.1                        05/14/2019                   GITWORKFLOWS(7)