dgit-maint-debrebase

dgit-maint-debrebase(7)              dgit              dgit-maint-debrebase(7)



NAME
       dgit - tutorial for package maintainers, using a workflow centered
       around git-debrebase(1)

INTRODUCTION
       This document describes elements of a workflow for maintaining a non-
       native Debian package using dgit.  We maintain the Debian delta as a
       series of git commits on our master branch.  We use git-debrebase(1) to
       shuffle our branch such that this series of git commits appears at the
       end of the branch.  All the public git history is fast-forwarding,
       i.e., we do not rewrite and force-push.

       Some advantages of this workflow:

       •   Manipulate the delta queue using the full power of git-rebase(1),
           instead of relying on quilt(1), and without having to switch back
           and forth between patches-applied and patches-unapplied branches
           when committing changes and trying to build, as with gbp-pq(1).

       •   If you are using 3.0 (quilt), provide your delta queue as a
           properly separated series of quilt patches in the source package
           that you upload to the archive (unlike with dgit-maint-merge(7)).

       •   Avoid the git tree being dirtied by the application or
           unapplication of patches, as they are always applied.

       •   Benefit from dgit's safety catches.  In particular, ensure that
           your upload always matches exactly your git HEAD.

       •   Provide your full git history in a standard format on dgit-repos,
           where it can benefit downstream dgit users, such as people using
           dgit to do an NMU (see dgit-nmu-simple(7) and dgit-user(7)).

       •   Minimise the amount you need to know about 3.0 (quilt) in order to
           maintain Debian source packages which use that format.

       This workflow is appropriate for packages where the Debian delta
       contains multiple pieces which interact, or which you don't expect to
       be able to upstream soon.  For packages with simple and/or short-lived
       Debian deltas, use of git-debrebase(1) introduces unneeded complexity.
       For such packages, consider the workflow described in
       dgit-maint-merge(7).

INITIAL DEBIANISATION
       This section explains how to start using this workflow with a new
       package.  It should be skipped when converting an existing package to
       this workflow.

   When upstream tags releases in git
       Suppose that the latest stable upstream release is 1.2.2, and this has
       been tagged '1.2.2' by upstream.

           % git clone -oupstream https://some.upstream/foo.git
           % cd foo
           % git verify-tag 1.2.2
           % git reset --hard 1.2.2
           % git branch --unset-upstream

       The final command detaches your master branch from the upstream remote,
       so that git doesn't try to push anything there, or merge unreleased
       upstream commits.  To maintain a copy of your packaging branch on
       salsa.debian.org in addition to dgit-repos, you can do something like
       this:

           % git remote add -f origin salsa.debian.org:Debian/foo.git
           % git push --follow-tags -u origin master

       Now go ahead and Debianise your package.  Make commits on the master
       branch, adding things in the debian/ directory, or patching the
       upstream source.  For technical reasons, it is essential that your
       first commit introduces the debian/ directory containing at least one
       file, and does nothing else. In other words, make a commit introducing
       debian/ before patching the upstream source.

       Finally, you need an orig tarball:

           % git deborig

       See git-deborig(1) if this fails.

       This tarball is ephemeral and easily regenerated, so we don't commit it
       anywhere (e.g. with tools like pristine-tar(1)).

       Comparing upstream's tarball releases

           The above assumes that you know how to build the package from git
           and that doing so is straightforward.

           If, as a user of the upstream source, you usually build from
           upstream tarball releases, rather than upstream git tags, you will
           sometimes find that the git tree doesn't contain everything that is
           in the tarball.

           Additional build steps may be needed.  For example, you may need
           your debian/rules to run autotools.

           You can compare the upstream tarball release, and upstream git tag,
           within git, by importing the tarball into git as described in the
           next section, using a different value for 'upstream-tag', and then
           using git-diff(1) to compare the imported tarball to the release
           tag.

       Using untagged upstream commits

           Sometimes upstream does not tag their releases, or you want to
           package an unreleased git snapshot.  In such a case you can create
           your own upstream release tag, of the form upstream/ver, where ver
           is the upstream version you plan to put in debian/changelog.  The
           upstream/ prefix ensures that your tag will not clash with any tags
           upstream later creates.

           For example, suppose that the latest upstream release is 1.2.2 and
           you want to package git commit ab34c21 which was made on
           2013-12-11.  A common convention is to use the upstream version
           number 1.2.2+git20131211.ab34c21 and so you could use

               % git tag -s upstream/1.2.2+git20131211.ab34c21 ab34c21

           to obtain a release tag, and then proceed as above.

   When upstream releases only tarballs
       Because we want to work in git, we need a virtual upstream branch with
       virtual release tags.  gbp-import-orig(1) can manage this for us.  To
       begin

           % mkdir foo
           % cd foo
           % git init
           % git checkout -b upstream
           % gbp import-orig \
               --upstream-branch=upstream --debian-branch=master \
               --upstream-tag='upstream/%(version)s' \
               --sign-tags --no-pristine-tar \
               ../foo_1.2.2.orig.tar.xz
           % git branch -f upstream

       This should leave you on the master branch.  Next, our upstream branch
       cannot be pushed to dgit-repos, but since we will need it whenever we
       import a new upstream version, we must push it somewhere.  The usual
       choice is salsa.debian.org:

           % git remote add -f origin salsa.debian.org:Debian/foo.git
           % git push --follow-tags -u origin master upstream

       You are now ready to proceed as above, making commits to the debian/
       directory and to the upstream source.  As above, for technical reasons,
       it is essential that your first commit introduces the debian/ directory
       containing at least one file, and does nothing else.  In other words,
       make a commit introducing debian/ before patching the upstream source.

       A convenient way to ensure this requirement is satisfied is to start by
       creating debian/gbp.conf:

           [DEFAULT]
           upstream-branch = upstream
           debian-branch = master
           upstream-tag = upstream/%(version)s

           sign-tags = True
           pristine-tar = False
           pristine-tar-commit = False

           [import-orig]
           merge = False

       and commit that:

           % git add debian/gbp.conf && git commit -m "create gbp.conf"

       Note that we couldn't create debian/gbp.conf before now for the same
       technical reasons which require our first commit to introduce debian/
       without patching the upstream source.  That's why we had to pass a lot
       of options to our first call to gbp-import-orig(1).

CONVERTING AN EXISTING PACKAGE
       This section explains how to convert an existing Debian package to this
       workflow.  It should be skipped when debianising a new package.

       If you have an existing git history that you have pushed to an ordinary
       git server like salsa.debian.org, we start with that.  If you don't
       already have it locally, you'll need to clone it, and obtain the
       corresponding orig.tar from the archive:

           % git clone salsa.debian.org:Debian/foo
           % cd foo
           % dgit setup-new-tree
           % origtargz

       If you don't have any existing git history, or you have history only on
       the special dgit-repos server, we start with dgit clone:

           % dgit clone foo
           % cd foo

       Then we make new upstream tags available:

           % git remote add -f upstream https://some.upstream/foo.git

       We now use a git debrebase convert-from-* command to convert your
       existing history to the git-debrebase(5) data model.  Which command you
       should use depends on some facts about your repository:

       (A) There is no delta queue.
           If there do not exist any Debian patches, use

               % git debrebase convert-from-gbp

       (B) There is a delta queue, and patches are unapplied.
           This is the standard git-buildpackage(1) workflow: there are Debian
           patches, but the upstream source is committed to git without those
           patches applied.  Use

               % git debrebase convert-from-gbp

           If you were not previously using dgit to upload your package (i.e.
           you were not using the workflow described in dgit-maint-gbp(7)),
           and you happen to have run dgit fetch sid in this clone of the
           repository, you will need to pass --fdiverged to this command.

       (C) There is a delta queue, and patches are applied.
           Use

               % git debrebase convert-from-dgit-view

       Finally, you need to ensure that your git HEAD is dgit-compatible,
       i.e., it is exactly what you would get if you deleted .git, invoked
       dpkg-buildpackage -S, and then unpacked the resultant source package.

       To achieve this, you might need to delete debian/source/local-options.
       One way to have dgit check your progress is to run dgit build-source.

GIT CONFIGURATION
       git-debrebase(1) does not yet support using git merge to merge
       divergent branches of development (see "OTHER MERGES" in
       git-debrebase(5)).  You should configure git such that git pull does
       not try to merge:

           % git config --local pull.rebase true

       Now when you pull work from other Debian contributors, git will rebase
       your work on top of theirs.

       If you use this clone for upstream development in addition to Debian
       packaging work, you may not want to set this global setting.  Instead,
       see the branch.autoSetupRebase and branch.<name>.rebase settings in
       git-config(5).

IMPORTING NEW UPSTREAM RELEASES
       There are two steps: obtaining git refs that correspond to the new
       release, and importing that release using git-debrebase(1).

   Obtaining the release
       When upstream tags releases in git

           % git fetch --tags upstream

       If you want to package an untagged upstream commit (because upstream
       does not tag releases or because you want to package an upstream
       development snapshot), see "Using untagged upstream commits" above.

       When upstream releases only tarballs

       You will need the debian/gbp.conf from "When upstream releases only
       tarballs", above.  You will also need your upstream branch.  Above, we
       pushed this to salsa.debian.org.  You will need to clone or fetch from
       there, instead of relying on dgit clone/dgit fetch alone.

       Then, either

           % gbp import-orig ../foo_1.2.3.orig.tar.xz

       or if you have a working watch file

           % gbp import-orig --uscan

   Importing the release
           % git debrebase new-upstream 1.2.3

       replacing 1.2.3 with upstream/1.2.3 if you imported a tarball.

       This invocation of git-debrebase(1) involves a git rebase.  You may
       need to resolve conflicts if the Debian delta queue does not apply
       cleanly to the new upstream source.

       If all went well, you can now review the merge of the new upstream
       release:

           git diff debian/1.2.2-1..HEAD -- . ':!debian'

       Also, diff with --name-status and --diff-filter=ADR to see just the
       list of added or removed files, which is useful to determine whether
       there are any new or deleted files that may need accounting for in your
       copyright file.

       If you obtained a tarball from upstream, you are ready to try a build.
       If you merged a git tag from upstream, you will first need to generate
       a tarball:

           % git deborig

EDITING THE DEBIAN PACKAGING
       Just make commits on master that change the contents of debian/.

EDITING THE DELTA QUEUE
   Adding new patches
       Adding new patches is straightforward: just make commits touching only
       files outside of the debian/ directory.  You can also use tools like
       git-revert(1), git-am(1) and git-cherry-pick(1).

   Editing patches: starting a debrebase
       git-debrebase(1) is a wrapper around git-rebase(1) which allows us to
       edit, re-order and delete patches.  Run

           % git debrebase -i

       to start an interactive rebase.  You can edit, re-order and delete
       commits just as you would during git rebase -i.

   Editing patches: finishing a debrebase
       After completing the git rebase, your branch will not be a fast-forward
       of the git HEAD you had before the rebase.  This means that we cannot
       push the branch anywhere.  If you are ready to upload, dgit push or
       dgit push-source will take care of fixing this up for you.

       If you are not yet ready to upload, and want to push your branch to a
       git remote such as salsa.debian.org,

           % git debrebase conclude

       Note that each time you conclude a debrebase you introduce a
       pseudomerge into your git history, which may make it harder to read.
       Try to do all of the editing of the delta queue that you think will be
       needed for this editing session in a single debrebase, so that there is
       a single debrebase stitch.

BUILDING AND UPLOADING
       You can use dpkg-buildpackage(1) for test builds.  When you are ready
       to build for an upload, use dgit sbuild, dgit pbuilder or dgit
       cowbuilder.

       Upload with dgit push or dgit push-source.  Remember to pass --new if
       the package is new in the target suite.

       In some cases where you used git debrebase convert-from-gbp since the
       last upload, it is not possible for dgit to make your history fast-
       forwarding from the history on dgit-repos.  In such cases you will have
       to pass --overwrite to dgit.  git-debrebase will normally tell you if
       this will be needed.

       Right before uploading, if you did not just already do so, you might
       want to have git-debrebase(1) shuffle your branch such that the Debian
       delta queue appears right at the tip of the branch you will push:

           % git debrebase
           % dgit push-source

       Note that this will introduce a new pseudomerge.

       After dgit pushing, be sure to git push to salsa.debian.org, if you're
       using that.

HANDLING DFSG-NON-FREE MATERIAL
   Illegal material
       Here we explain how to handle material that is merely DFSG-non-free.
       Material which is legally dangerous (for example, files which are
       actually illegal) cannot be handled this way.

       If you encounter possibly-legally-dangerous material in the upstream
       source code you should seek advice.  It is often best not to make a
       fuss on a public mailing list (at least, not at first).  Instead, email
       your archive administrators.  For Debian that is
        To: dgit-owner@debian.org, ftpmaster@ftp-master.debian.org

   DFSG-non-free: When upstream tags releases in git
       Our approach is to maintain a DFSG-clean upstream branch, and create
       tags on this branch for each release that we want to import.  We then
       import those tags per "Importing the release", above.  In the case of a
       new package, we base our initial Debianisation on our first DFSG-clean
       tag.

       For the first upstream release that requires DFSG filtering:

           % git checkout -b upstream-dfsg 1.2.3
           % git rm evil.bin
           % git commit -m "upstream version 1.2.3 DFSG-cleaned"
           % git tag -s 1.2.3+dfsg
           % git checkout master

       Now either proceed with "Importing the release" on the 1.2.3+dfsg tag,
       or in the case of a new package,

           % git branch --unset-upstream
           % git reset --hard 1.2.3+dfsg

       and proceed with "INITIAL DEBIANISATION".

       For subsequent releases (whether or not they require additional
       filtering):

           % git checkout upstream-dfsg
           % git merge 1.2.4
           % git rm further-evil.bin # if needed
           % git commit -m "upstream version 1.2.4 DFSG-cleaned" # if needed
           % git tag -s 1.2.4+dfsg
           % git checkout master
           % # proceed with "Importing the release" on 1.2.4+dfsg tag

       Our upstream-dfsg branch cannot be pushed to dgit-repos, but since we
       will need it whenever we import a new upstream version, we must push it
       somewhere.  Assuming that you have already set up an origin remote per
       the above,

           % git push --follow-tags -u origin master upstream-dfsg

   DFSG-non-free: When upstream releases only tarballs
       The easiest way to handle this is to add a Files-Excluded field to
       debian/copyright, and a uversionmangle setting in debian/watch.  See
       uscan(1).  Alternatively, see the --filter option detailed in
       gbp-import-orig(1).

INCORPORATING NMUS
       In the simplest case,

           % dgit fetch
           % git merge --ff-only dgit/dgit/sid

       If that fails, because your branch and the NMUers' work represent
       divergent branches of development, you have a number of options.  Here
       we describe the two simplest.

       Note that you should not try to resolve the divergent branches by
       editing files in debian/patches.  Changes there would either cause
       trouble, or be overwritten by git-debrebase(1).

   Rebasing your work onto the NMU
           % git rebase dgit/dgit/sid

       If the NMUer added new commits modifying the upstream source, you will
       probably want to debrebase before your next upload to tidy those up.

       For example, the NMUer might have used git-revert(1) to unapply one of
       your patches.  A debrebase can be used to strip both the patch and the
       reversion from the delta queue.

   Manually applying the debdiff
       If you cannot rebase because you have already pushed to
       salsa.debian.org, say, you can manually apply the NMU debdiff, commit
       and debrebase.  The next dgit push will require --overwrite.

HINTS AND TIPS
   Minimising pseudomerges
       Above we noted that each time you conclude a debrebase, you introduce a
       pseudomerge into your git history, which may make it harder to read.

       A simple convention you can use to minimise the number of pseudomerges
       is to git debrebase conclude only right before you upload or push to
       salsa.debian.org.

       It is possible, though much less convenient, to reduce the number of
       pseudomerges yet further.  We debrebase only (i) when importing a new
       release, and (ii) right before uploading.  Instead of editing the
       existing delta queue, you append fixup commits (and reversions of
       commits) that alter the upstream source to the required state.  You can
       push and pull to and from salsa.debian.org during this.  Just before
       uploading, you debrebase, once, to tidy everything up.

   The debian/patches directory
       In this workflow, debian/patches is purely an output of
       git-debrebase(1).  You should not make changes there.  They will either
       cause trouble, or be ignored and overwritten by git-debrebase(1).

       debian/patches will often be out-of-date because git-debrebase(1) will
       only regenerate it when it needs to.  So you should not rely on the
       information in that directory.  When preparing patches to forward
       upstream, you should use git-format-patch(1) on git commits, rather
       than sending files from debian/patches.

   Upstream branches
       In this workflow, we specify upstream tags rather than any branches.

       Except when (i) upstream releases only tarballs, (ii) we require DFSG
       filtering, or (iii) you also happen to be involved in upstream
       development, we do not maintain any local branch corresponding to
       upstream, except temporary branches used to prepare patches for
       forwarding, and the like.

       The idea here is that from Debian's point of view, upstream releases
       are immutable points in history.  We want to make sure that we are
       basing our Debian package on a properly identified upstream version,
       rather than some arbitrary commit on some branch.  Tags are more useful
       for this.

       Upstream's branches remain available as the git remote tracking
       branches for your upstream remote, e.g. remotes/upstream/master.

   The first ever dgit push
       If this is the first ever dgit push of the package, consider passing
       --deliberately-not-fast-forward instead of --overwrite.  This avoids
       introducing a new origin commit into your git history.  (This origin
       commit would represent the most recent non-dgit upload of the package,
       but this should already be represented in your git history.)

   Inspecting the history
       The git history made by git-debrebase can seem complicated.  Here are
       some suggestions for helpful invocations of gitk and git.  They can be
       adapted for other tools like tig(1), git-log(1), magit, etc.

       History of package in Debian, disregarding history from upstream:

           % gitk --first-parent

           In a laundered branch, the delta queue is at the top.

       History of the packaging, excluding the delta queue:

           % gitk :/debian :!/debian/patches

       Just the delta queue (i.e. Debian's changes to upstream):

           % gitk --first-parent -- :/ :!/debian

       Full history including old versions of the delta queue:

           % gitk --date-order

           The "Declare fast forward" commits you see have an older history
           (usually, an older delta queue) as one parent, and a newer history
           as the other.  --date-order makes gitk show the delta queues in the
           right order.

       Complete diff since the last upload:

           % git diff dgit/dgit/sid..HEAD -- :/ :!/debian/patches

           This includes changes to upstream files.

       Interdiff of delta queue since last upload, if you really want it:

           % git debrebase make-patches
           % git diff dgit/dgit/sid..HEAD -- debian/patches

       And of course there is:

           % git debrebase status

   Alternative ways to start a debrebase
       Above we started an interactive debrebase by invoking git-debrebase(1)
       like this:

           % git debrebase -i

       It is also possible to perform a non-interactive rebase, like this:

           % git debrebase -- [git-rebase options...]

       A third alternative is to have git-debrebase(1) shuffle all the Debian
       changes to the end of your branch, and then manipulate them yourself
       using git-rebase(1) directly.  For example,

           % git debrebase
           % git rebase -i HEAD~5      # there are 4 Debian patches

       If you take this approach, you should be very careful not to start the
       rebase too early, including before the most recent pseudomerge.  git-
       rebase without a base argument will often start the rebase too early,
       and should be avoided.  Run git-debrebase instead.  See also "ILLEGAL
       OPERATIONS" in git-debrebase(5).

SEE ALSO
       dgit(1), dgit(7), git-debrebase(1), git-debrebase(5)

AUTHOR
       This tutorial was written and is maintained by Sean Whitton
       <spwhitton@spwhitton.name>.  It contains contributions from other dgit
       contributors too - see the dgit copyright file.



perl v5.28.2                    Debian Project         dgit-maint-debrebase(7)