NAME | SYNOPSIS | DESCRIPTION | SEPARATE CHANGES | MANAGING BRANCHES | DISTRIBUTED WORKFLOWS | SEE ALSO | GIT | COLOPHON

GITWORKFLOWS(7)                  Git Manual                  GITWORKFLOWS(7)

NAME         top

       gitworkflows - An overview of recommended workflows with Git

SYNOPSIS         top

       git *

DESCRIPTION         top

       This document attempts to write down and motivate some of the
       workflow elements used for git.git itself. Many ideas apply in
       general, though the full workflow is rarely required for smaller
       projects with fewer people involved.

       We formulate a set of rules for quick reference, while the prose
       tries to motivate each of them. Do not always take them literally;
       you should value good reasons for your actions higher than manpages
       such as this one.

SEPARATE CHANGES         top

       As a general rule, you should try to split your changes into small
       logical steps, and commit each of them. They should be consistent,
       working independently of any later commits, pass the test suite, etc.
       This makes the review process much easier, and the history much more
       useful for later inspection and analysis, for example with
       git-blame(1) and git-bisect(1).

       To achieve this, try to split your work into small steps from the
       very beginning. It is always easier to squash a few commits together
       than to split one big commit into several. Don’t be afraid of making
       too small or imperfect steps along the way. You can always go back
       later and edit the commits with git rebase --interactive before you
       publish them. You can use git stash save --keep-index to run the test
       suite independent of other uncommitted changes; see the EXAMPLES
       section of git-stash(1).

MANAGING BRANCHES         top

       There are two main tools that can be used to include changes from one
       branch on another: git-merge(1) and git-cherry-pick(1).

       Merges have many advantages, so we try to solve as many problems as
       possible with merges alone. Cherry-picking is still occasionally
       useful; see "Merging upwards" below for an example.

       Most importantly, merging works at the branch level, while
       cherry-picking works at the commit level. This means that a merge can
       carry over the changes from 1, 10, or 1000 commits with equal ease,
       which in turn means the workflow scales much better to a large number
       of contributors (and contributions). Merges are also easier to
       understand because a merge commit is a "promise" that all changes
       from all its parents are now included.

       There is a tradeoff of course: merges require a more careful branch
       management. The following subsections discuss the important points.

   Graduation
       As a given feature goes from experimental to stable, it also
       "graduates" between the corresponding branches of the software.
       git.git uses the following integration branches:

       ·   maint tracks the commits that should go into the next
           "maintenance release", i.e., update of the last released stable
           version;

       ·   master tracks the commits that should go into the next release;

       ·   next is intended as a testing branch for topics being tested for
           stability for master.

       There is a fourth official branch that is used slightly differently:

       ·   pu (proposed updates) is an integration branch for things that
           are not quite ready for inclusion yet (see "Integration Branches"
           below).

       Each of the four branches is usually a direct descendant of the one
       above it.

       Conceptually, the feature enters at an unstable branch (usually next
       or pu), and "graduates" to master for the next release once it is
       considered stable enough.

   Merging upwards
       The "downwards graduation" discussed above cannot be done by actually
       merging downwards, however, since that would merge all changes on the
       unstable branch into the stable one. Hence the following:

       Example 1. Merge upwards

       Always commit your fixes to the oldest supported branch that require
       them. Then (periodically) merge the integration branches upwards into
       each other.

       This gives a very controlled flow of fixes. If you notice that you
       have applied a fix to e.g. master that is also required in maint, you
       will need to cherry-pick it (using git-cherry-pick(1)) downwards.
       This will happen a few times and is nothing to worry about unless you
       do it very frequently.

   Topic branches
       Any nontrivial feature will require several patches to implement, and
       may get extra bugfixes or improvements during its lifetime.

       Committing everything directly on the integration branches leads to
       many problems: Bad commits cannot be undone, so they must be reverted
       one by one, which creates confusing histories and further error
       potential when you forget to revert part of a group of changes.
       Working in parallel mixes up the changes, creating further confusion.

       Use of "topic branches" solves these problems. The name is pretty
       self explanatory, with a caveat that comes from the "merge upwards"
       rule above:

       Example 2. Topic branches

       Make a side branch for every topic (feature, bugfix, ...). Fork it
       off at the oldest integration branch that you will eventually want to
       merge it into.

       Many things can then be done very naturally:

       ·   To get the feature/bugfix into an integration branch, simply
           merge it. If the topic has evolved further in the meantime, merge
           again. (Note that you do not necessarily have to merge it to the
           oldest integration branch first. For example, you can first merge
           a bugfix to next, give it some testing time, and merge to maint
           when you know it is stable.)

       ·   If you find you need new features from the branch other to
           continue working on your topic, merge other to topic. (However,
           do not do this "just habitually", see below.)

       ·   If you find you forked off the wrong branch and want to move it
           "back in time", use git-rebase(1).

       Note that the last point clashes with the other two: a topic that has
       been merged elsewhere should not be rebased. See the section on
       RECOVERING FROM UPSTREAM REBASE in git-rebase(1).

       We should point out that "habitually" (regularly for no real reason)
       merging an integration branch into your topics — and by extension,
       merging anything upstream into anything downstream on a regular basis
       — is frowned upon:

       Example 3. Merge to downstream only at well-defined points

       Do not merge to downstream except with a good reason: upstream API
       changes affect your branch; your branch no longer merges to upstream
       cleanly; etc.

       Otherwise, the topic that was merged to suddenly contains more than a
       single (well-separated) change. The many resulting small merges will
       greatly clutter up history. Anyone who later investigates the history
       of a file will have to find out whether that merge affected the topic
       in development. An upstream might even inadvertently be merged into a
       "more stable" branch. And so on.

   Throw-away integration
       If you followed the last paragraph, you will now have many small
       topic branches, and occasionally wonder how they interact. Perhaps
       the result of merging them does not even work? But on the other hand,
       we want to avoid merging them anywhere "stable" because such merges
       cannot easily be undone.

       The solution, of course, is to make a merge that we can undo: merge
       into a throw-away branch.

       Example 4. Throw-away integration branches

       To test the interaction of several topics, merge them into a
       throw-away branch. You must never base any work on such a branch!

       If you make it (very) clear that this branch is going to be deleted
       right after the testing, you can even publish this branch, for
       example to give the testers a chance to work with it, or other
       developers a chance to see if their in-progress work will be
       compatible. git.git has such an official throw-away integration
       branch called pu.

   Branch management for a release
       Assuming you are using the merge approach discussed above, when you
       are releasing your project you will need to do some additional branch
       management work.

       A feature release is created from the master branch, since master
       tracks the commits that should go into the next feature release.

       The master branch is supposed to be a superset of maint. If this
       condition does not hold, then maint contains some commits that are
       not included on master. The fixes represented by those commits will
       therefore not be included in your feature release.

       To verify that master is indeed a superset of maint, use git log:

       Example 5. Verify master is a superset of maint

       git log master..maint

       This command should not list any commits. Otherwise, check out master
       and merge maint into it.

       Now you can proceed with the creation of the feature release. Apply a
       tag to the tip of master indicating the release version:

       Example 6. Release tagging

       git tag -s -m "Git X.Y.Z" vX.Y.Z master

       You need to push the new tag to a public Git server (see "DISTRIBUTED
       WORKFLOWS" below). This makes the tag available to others tracking
       your project. The push could also trigger a post-update hook to
       perform release-related items such as building release tarballs and
       preformatted documentation pages.

       Similarly, for a maintenance release, maint is tracking the commits
       to be released. Therefore, in the steps above simply tag and push
       maint rather than master.

   Maintenance branch management after a feature release
       After a feature release, you need to manage your maintenance
       branches.

       First, if you wish to continue to release maintenance fixes for the
       feature release made before the recent one, then you must create
       another branch to track commits for that previous release.

       To do this, the current maintenance branch is copied to another
       branch named with the previous release version number (e.g.
       maint-X.Y.(Z-1) where X.Y.Z is the current release).

       Example 7. Copy maint

       git branch maint-X.Y.(Z-1) maint

       The maint branch should now be fast-forwarded to the newly released
       code so that maintenance fixes can be tracked for the current
       release:

       Example 8. Update maint to new release

       ·   git checkout maint

       ·   git merge --ff-only master

       If the merge fails because it is not a fast-forward, then it is
       possible some fixes on maint were missed in the feature release. This
       will not happen if the content of the branches was verified as
       described in the previous section.

   Branch management for next and pu after a feature release
       After a feature release, the integration branch next may optionally
       be rewound and rebuilt from the tip of master using the surviving
       topics on next:

       Example 9. Rewind and rebuild next

       ·   git checkout next

       ·   git reset --hard master

       ·   git merge ai/topic_in_next1

       ·   git merge ai/topic_in_next2

       ·   ...

       The advantage of doing this is that the history of next will be
       clean. For example, some topics merged into next may have initially
       looked promising, but were later found to be undesirable or
       premature. In such a case, the topic is reverted out of next but the
       fact remains in the history that it was once merged and reverted. By
       recreating next, you give another incarnation of such topics a clean
       slate to retry, and a feature release is a good point in history to
       do so.

       If you do this, then you should make a public announcement indicating
       that next was rewound and rebuilt.

       The same rewind and rebuild process may be followed for pu. A public
       announcement is not necessary since pu is a throw-away branch, as
       described above.

DISTRIBUTED WORKFLOWS         top

       After the last section, you should know how to manage topics. In
       general, you will not be the only person working on the project, so
       you will have to share your work.

       Roughly speaking, there are two important workflows: merge and patch.
       The important difference is that the merge workflow can propagate
       full history, including merges, while patches cannot. Both workflows
       can be used in parallel: in git.git, only subsystem maintainers use
       the merge workflow, while everyone else sends patches.

       Note that the maintainer(s) may impose restrictions, such as
       "Signed-off-by" requirements, that all commits/patches submitted for
       inclusion must adhere to. Consult your project’s documentation for
       more information.

   Merge workflow
       The merge workflow works by copying branches between upstream and
       downstream. Upstream can merge contributions into the official
       history; downstream base their work on the official history.

       There are three main tools that can be used for this:

       ·   git-push(1) copies your branches to a remote repository, usually
           to one that can be read by all involved parties;

       ·   git-fetch(1) that copies remote branches to your repository; and

       ·   git-pull(1) that does fetch and merge in one go.

       Note the last point. Do not use git pull unless you actually want to
       merge the remote branch.

       Getting changes out is easy:

       Example 10. Push/pull: Publishing branches/topics

       git push <remote> <branch> and tell everyone where they can fetch
       from.

       You will still have to tell people by other means, such as mail. (Git
       provides the git-request-pull(1) to send preformatted pull requests
       to upstream maintainers to simplify this task.)

       If you just want to get the newest copies of the integration
       branches, staying up to date is easy too:

       Example 11. Push/pull: Staying up to date

       Use git fetch <remote> or git remote update to stay up to date.

       Then simply fork your topic branches from the stable remotes as
       explained earlier.

       If you are a maintainer and would like to merge other people’s topic
       branches to the integration branches, they will typically send a
       request to do so by mail. Such a request looks like

           Please pull from
               <url> <branch>

       In that case, git pull can do the fetch and merge in one go, as
       follows.

       Example 12. Push/pull: Merging remote topics

       git pull <url> <branch>

       Occasionally, the maintainer may get merge conflicts when he tries to
       pull changes from downstream. In this case, he can ask downstream to
       do the merge and resolve the conflicts themselves (perhaps they will
       know better how to resolve them). It is one of the rare cases where
       downstream should merge from upstream.

   Patch workflow
       If you are a contributor that sends changes upstream in the form of
       emails, you should use topic branches as usual (see above). Then use
       git-format-patch(1) to generate the corresponding emails (highly
       recommended over manually formatting them because it makes the
       maintainer’s life easier).

       Example 13. format-patch/am: Publishing branches/topics

       ·   git format-patch -M upstream..topic to turn them into
           preformatted patch files

       ·   git send-email --to=<recipient> <patches>

       See the git-format-patch(1) and git-send-email(1) manpages for
       further usage notes.

       If the maintainer tells you that your patch no longer applies to the
       current upstream, you will have to rebase your topic (you cannot use
       a merge because you cannot format-patch merges):

       Example 14. format-patch/am: Keeping topics up to date

       git pull --rebase <url> <branch>

       You can then fix the conflicts during the rebase. Presumably you have
       not published your topic other than by mail, so rebasing it is not a
       problem.

       If you receive such a patch series (as maintainer, or perhaps as a
       reader of the mailing list it was sent to), save the mails to files,
       create a new topic branch and use git am to import the commits:

       Example 15. format-patch/am: Importing patches

       git am < patch

       One feature worth pointing out is the three-way merge, which can help
       if you get conflicts: git am -3 will use index information contained
       in patches to figure out the merge base. See git-am(1) for other
       options.

SEE ALSO         top

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

GIT         top

       Part of the git(1) suite

COLOPHON         top

       This page is part of the git (Git distributed version control system)
       project.  Information about the project can be found at 
       ⟨http://git-scm.com/⟩.  If you have a bug report for this manual page,
       see ⟨http://git-scm.com/community⟩.  This page was obtained from the
       project's upstream Git repository ⟨https://github.com/git/git.git⟩ on
       2017-07-05.  If you discover any rendering problems in this HTML ver‐
       sion of the page, or you believe there is a better or more up-to-date
       source for the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original man‐
       ual page), send a mail to man-pages@man7.org

Git 2.12.0.rc2                   02/18/2017                  GITWORKFLOWS(7)

Pages that refer to this page: git(1)git-cherry(1)gittutorial(7)