NAME

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

INTRODUCTION

       This document describes elements of a workflow for maintaining a non-native Debian package using dgit.
       The workflow makes the following opinionated assumptions:

       •   Git histories should be the non-linear histories produced by git-merge(1), preserving all information
           about divergent development that was later brought together.

       •   Maintaining  convenient  and  powerful  git  workflows  takes priority over the usefulness of the raw
           Debian source package.  The Debian archive is thought of as an output format.

           For example, we don't spend time curating a series of quilt  patches.   However,  in  straightforward
           cases, the information such a series would contain is readily available from dgit-repos.

       •   It  is  more  important  to  have  the Debian package's git history be a descendent of upstream's git
           history than to use exactly the orig.tar that upstream makes available for download.

       This workflow is less suitable for some packages.  When the Debian delta contains multiple  pieces  which
       interact,  or  which you aren't going to be able to upstream soon, it might be preferable to maintain the
       delta as a rebasing patch series.  For such  a  workflow  see  for  example  dgit-maint-debrebase(7)  and
       dgit-maint-gbp(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.  If you want 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.  Just make commits on the master branch, adding  things  in  the
       debian/ directory.  If you need to patch the upstream source, just make commits that change files outside
       of  the  debian/  directory.   It  is best to separate commits that touch debian/ from commits that touch
       upstream source, so that the latter can be cherry-picked by upstream.

       Note that there is no need to maintain a separate  'upstream'  branch,  unless  you  also  happen  to  be
       involved  in  upstream  development.   We  work  with upstream tags rather than any branches, except when
       forwarding patches (see FORWARDING PATCHES UPSTREAM, below).

       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)).

       Verifying upstream's tarball releases

           It can be a good idea to compare upstream's released tarballs with the release tags, at least for the
           first  upload  of the package.  If they are different, you might need to add some additional steps to
           your debian/rules, such as running autotools.

           A convenient way to perform this check is to  import  the  tarball  as  described  in  the  following
           section, using a different value for 'upstream-tag', and then use git-diff(1) to compare the imported
           tarball  to the release tag.  If they are the same, you can use upstream's tarball instead of running
           git-deborig(1).

       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.

           One can generate such a versioned tag using git show's --pretty option.  e.g.:

               % git tag -s upstream/$(git show --date=format:%Y%m%d --pretty=format:"1.2.2+git%cd.%h" --quiet upstream/main) upstream/main

   When upstream releases only tarballs
       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

       Now create 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-mode = merge
           merge = False

       gbp-import-orig(1) requires a pre-existing upstream branch:

           % git add debian/gbp.conf && git commit -m "create gbp.conf"
           % git checkout --orphan upstream
           % git rm -rf .
           % git commit --allow-empty -m "initial, empty branch for upstream source"
           % git checkout -f master

       Then we can import the upstream version:

           % gbp import-orig --merge --merge-mode=replace ../foo_1.2.2.orig.tar.xz

       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  both  the  upstream  source  and  the  debian/
       directory.

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.

   No existing git history
           % dgit clone foo
           % cd foo
           % git remote add -f upstream https://some.upstream/foo.git

   Existing git history using another workflow
       First, if you don't already have the git history locally, clone it, and obtain the corresponding orig.tar
       from the archive:

           % git clone git.debian.org:collab-maint/foo
           % cd foo
           % origtargz

       Now dump any existing patch queue:

           % git rm -rf debian/patches
           % git commit -m "drop existing quilt patch queue"

       Then make new upstream tags available:

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

       Now you simply need to ensure that your git HEAD is dgit-compatible, i.e., it is exactly what  you  would
       get if you ran dpkg-buildpackage -i'(?:^|/)\.git(?:/|$)' -I.git -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.

       The first dgit push will require --trust-changelog.  If this is the first ever dgit push of the  package,
       consider passing --deliberately-not-fast-forward instead of --trust-changelog.  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.)

SOURCE PACKAGE AND GIT CONFIGURATION

   dgit configuration
       We must tell dgit not to try to maintain a linear queue of patches to the upstream source:

           git config dgit.default.quilt-mode single

       This command should be executed in each git clone of this package, including your co-maintainer's.  Don't
       set it more globally, because it is not a good default for working on Debian source packages in general.

   debian/source/options
       We set a source package option to help dpkg handle changes to the upstream source:

           auto-commit

       You don't need to create this file if you are using the version 1.0 source package format.

BUILDING AND UPLOADING

       Use dgit build, dgit sbuild, dgit pbuilder, dgit cowbuilder, dgit push-source,  and  dgit  push-built  as
       detailed in dgit(1).  If any command fails, dgit will provide a carefully-worded error message explaining
       what  you  should  do.  If it's not clear, file a bug against dgit.  Remember to pass --new for the first
       upload.

       If you want to upload with git-debpush(1), for the first upload you should pass the --quilt=single  quilt
       mode option (see git-debpush(1)).

       As  another alternative to dgit build and friends, you can use a tool like gitpkg(1).  This works because
       like dgit, gitpkg(1) enforces that HEAD has exactly the contents of the  source  package.   gitpkg(1)  is
       highly  configurable,  and  one  dgit user reports using it to produce and test multiple source packages,
       from different branches corresponding to each of the current Debian suites.

       If you want to skip dgit's checks while iterating on a problem with the package build (for  example,  you
       don't want to commit your changes to git), you can just run dpkg-buildpackage(1) or debuild(1) instead.

NEW UPSTREAM RELEASES

   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

       In the following, replace 1.2.3 with upstream/1.2.3.

   Reviewing & merging the release
       It's a good idea to preview the merge of the new upstream release.  First, just  check  for  any  new  or
       deleted files that may need accounting for in your copyright file:

           % git diff --name-status --diff-filter=ADR master..1.2.3 -- . ':!debian'

       You can then review the full merge diff:

           % git merge-tree `git merge-base master 1.2.3` master 1.2.3 | $PAGER

       Once you're satisfied with what will be merged, update your package:

           % git merge 1.2.3
           % dch -v1.2.3-1 New upstream release.
           % git add debian/changelog && git commit -m changelog

       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

HANDLING DFSG-NON-FREE MATERIAL

   When upstream tags releases in git
       We create a DFSG-clean tag to merge to master:

           % git checkout -b pre-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
           % git branch -D pre-dfsg

       Before merging the new 1.2.3+dfsg tag to master, you should first determine whether it would  be  legally
       dangerous for the non-free material to be publicly accessible in the git history on dgit-repos.

       If it would be dangerous, there is a big problem; in this case please consult your archive administrators
       (for    Debian    this   is   the   dgit   administrator   dgit-owner@debian.org   and   the   ftpmasters
       ftpmaster@ftp-master.debian.org).

   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).

FORWARDING PATCHES UPSTREAM

       The basic steps are:

       1.  Create a new branch based off upstream's master branch.

       2.  git-cherry-pick(1) commits from your master branch onto your new branch.

       3.  Push   the   branch   somewhere  and  ask  upstream  to  merge  it,  or  use  git-format-patch(1)  or
           git-request-pull(1).

       For example (and it is only an example):

           % # fork foo.git on GitHub
           % git remote add -f fork git@github.com:spwhitton/foo.git
           % git checkout -b fix-error upstream/master
           % git config branch.fix-error.pushRemote fork
           % git cherry-pick master^2
           % git push
           % # submit pull request on GitHub

       Note that when you merge an upstream release  containing  your  forwarded  patches,  git  and  dgit  will
       transparently handle "dropping" the patches that have been forwarded, "retaining" the ones that haven't.

INCORPORATING NMUS

           % dgit pull

       Alternatively,  you  can  apply  the  NMU  diff  to  your  repository.   The  next push will then require
       --trust-changelog.

SEE ALSO

       dgit(1), dgit(7), gitrevisions(7)

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 v5.38.2                                     Debian Project                              dgit-maint-merge(7)