=head1 NAME dgit - tutorial for package maintainers, using a workflow centered around git-debrebase(1) =head1 INTRODUCTION This document describes elements of a workflow for maintaining a non-native Debian package using B. 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. This does not involve rewriting any public git history. Some advantages of this workflow: =over 4 =item Manipulate the patch queue using the full power of git-rebase(1), instead of relying on quilt(1), and without having to switch away to another branch, as with gbp-pq(1). =item Avoid the git tree being dirtied by the application or unapplication of patches, as they are always applied. =item Benefit from dgit's safety catches. In particular, ensure that your upload always matches exactly your git HEAD. =item Provide your full git history in a standard format on B, 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)). =back 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) might introduce unneeded complexity. For such packages, consider the workflow described in dgit-maint-merge(7). =head1 INITIAL DEBIANISATION =head2 When upstream tags releases in git 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. Suppose that the latest stable upstream release is 1.2.2, and this has been tagged '1.2.2' by upstream. =over 4 % 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 =back 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 B in addition to B, you can do something like this: =over 4 % git remote add -f origin salsa.debian.org:Debian/foo.git % git push --follow-tags -u origin master =back Now go ahead and Debianise your package. Just make commits on the master branch, adding things in the I directory. If you need to patch the upstream source, see "EDITING THE PATCH QUEUE", below. 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: =over 4 % git deborig =back 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)). =head3 Verifying upstream's tarball releases =over 4 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 I, 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). =back =head2 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 =over 4 % mkdir foo % cd foo % git init =back Now create I: =over 4 [DEFAULT] upstream-branch = upstream debian-branch = master upstream-tag = %(version)s sign-tags = True pristine-tar = False pristine-tar-commit = False [import-orig] merge-mode = merge =back gbp-import-orig(1) requires a pre-existing upstream branch: =over 4 % 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 =back Then we can import the upstream version: =over 4 % gbp import-orig --merge-mode=replace ../foo_1.2.2.orig.tar.xz =back Our upstream branch cannot be pushed to B, but since we will need it whenever we import a new upstream version, we must push it somewhere. The usual choice is B: =over 4 % git remote add -f origin salsa.debian.org:Debian/foo.git % git push --follow-tags -u origin master upstream =back You are now ready to proceed as above, making commits to the I directory. =head1 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. =head2 No existing git history =over 4 % dgit clone foo % cd foo % git remote add -f upstream https://some.upstream/foo.git =back =head2 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: =over 4 % git clone salsa.debian.org:Debian/foo % cd foo % origtargz =back If your tree is patches-unapplied, you will need to make a commit corresponding to each of the quilt patches. gbp-pq(1) can do this for us: =over 4 % gbp pq import % gbp pq switch % git merge --ff-only patch-queue/master % gbp pq drop =back Then make new upstream tags available: =over 4 % git remote add -f upstream https://some.upstream/foo.git =back =for dgit-test dpkg-source-ignores begin 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 B and then unpacked the resultant source package. =for dgit-test dpkg-source-ignores end To achieve this, you might need to delete I. One way to have dgit check your progress is to run B. The first dgit push will require I<--overwrite>. If this is the first ever dgit push of the package, consider passing I<--deliberately-not-fast-forward> instead of I<--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.) =head1 IMPORTING NEW UPSTREAM RELEASES =head2 Obtaining the release =head3 When upstream tags releases in git =over 4 % git remote update =back =head3 When upstream releases only tarballs You will need the I from "When upstream releases only tarballs", above. You will also need your upstream branch. Above, we pushed this to B. You will need to clone or fetch from there, instead of relying on B/B alone. Then, either =over 4 % gbp import-orig --no-merge ../foo_1.2.3.orig.tar.xz =back or if you have a working watch file =over 4 % gbp import-orig --no-merge --uscan =back =head2 Importing the release =over 4 % git debrebase new-upstream-v0 1.2.3 % dch -v1.2.3-1 New upstream release. % git add debian/changelog && git commit -m changelog =back You can now review the merge of the new upstream release: =over 4 git diff debian/1.2.2-1..HEAD -- . ':!debian' =back Pass I<--stat> just to see the list of changed files, which is useful to determine whether there are any new or deleted files to 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: =over 4 % git deborig =back =head1 EDITING THE PATCH QUEUE =head2 Adding new patches Adding new patches is straightforward: just make commits touching only files outside of the I directory. You can also use tools like git-revert(1), git-am(1) and git-cherrypick(1). =head2 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 =over 4 % git debrebase =back to start an interactive rebase. You can edit, re-order and delete commits just as you would during B. Alternatively, you can perform a non-interactive rebase like this: =over 4 % git debrebase -- [git-rebase options...] =back For example, =over 4 % git debrebase -- --autosquash =back 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). For example, =over 4 % git debrebase launder % git rebase -i HEAD^5 # there are 4 Debian patches =back =head2 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, B or B 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 B, =over 4 % git debrebase stitch =back Note that each time you stitch 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 patch queue that you think will be needed for this upload in a single debrebase, so that there is a single debrebase stitch. A strategy is to debrebase only right before you upload. Before that point, instead of editing the existing patch series, you append fixup commits (and reversions of commits) that alter the upstream source to the required state. You can freely push and pull from B during this. Just before uploading, you debrebase to tidy everything up. =head1 BUILDING AND UPLOADING Use B, B, B and B 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 I<--new> for the first upload. After dgit pushing, be sure to git push to B, if you're using that. As an alternative to B 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. =head2 Laundering the patch queue before uploading Just before you B or B, you might want to have git-debrebase(1) shuffle your branch such that the Debian patch queue appears at the end: =over 4 % git debrebase launder % dgit push-source =back Note that this will introduce a new pseudomerge. =head1 HANDLING DFSG-NON-FREE MATERIAL =head2 When upstream tags releases in git We create a DFSG-clean tag to import to master: =over 4 % 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 =back Before invoking B, you should first determine whether it would be legally dangerous for the non-free material to be publicly accessible in the git history on B. 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). =head2 When upstream releases only tarballs The easiest way to handle this is to add a B field to I, and a B setting in I. See uscan(1). Alternatively, see the I<--filter> option detailed in gbp-import-orig(1). =head1 FORWARDING PATCHES UPSTREAM The basic steps are: =over 4 =item 1. Create a new branch based off upstream's master branch. =item 2. git-cherry-pick(1) commits from your master branch onto your new branch. =item 3. Push the branch somewhere and ask upstream to merge it, or use git-format-patch(1) or git-request-pull(1). =back For example (and it is only an example): =over 4 % # 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 =back Note that when you merge an upstream release containing your forwarded patches, a debrebase will transparently handle "dropping" the patches that have been forwarded, "retaining" the ones that haven't. =head1 INCORPORATING NMUS =over 4 % dgit pull =back 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 will strip both the patch and the reversion from the patch series. =head1 SEE ALSO dgit(1), dgit(7) =head1 AUTHOR This tutorial was written and is maintained by Sean Whitton . It contains contributions from other dgit contributors too - see the dgit copyright file.