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Re: Git and tarballs

Wolodja Wentland <babilen@gmail.com> writes:

> I've recently started to work on some packages and am not sure if I
> follow best practices when packaging software from git repositories with
> git-buildpackage.


I do the following for OpenAFS (see the supporting scripts in the openafs
source package) based on work done by Sam Hartman for krb5, and I'm very
happy with it.  I'm probably going to eventually adopt the same approach
for all other software with a Git upstream.

The key feature is that the import-upstream script imports the tarball
contents but commits it as a merge between the upstream tag and the local
upstream branch, which preserves all of upstream's commit history while
simultaneously including in the upstream branch any tarball-generated
files that aren't in Git.  This isn't required for OpenAFS, but for some
other packages I want to use some of the files that are generated as part
of the upstream tarball release but aren't checked in.

(This is part of debian/README.source for the openafs package.)

Importing a New Upstream Release

    We want to be able to use Git to cherry-pick fixes from upstream, but
    we want to base the Debian packages on the upstream tarball releases.
    We also need to strip some non-DFSG files from the upstream tarball
    releases and imported code, and want to drop the WINNT directory to
    save some space.  This means we follow a slightly complicated method
    for importing a new upstream release.

    Follow the following procedure to import a new upstream release:

    1. Update the package version in debian/changelog to match the new
       upstream version.  If the new upstream version is a release
       candidate, don't forget to add "~" before "rc" so that the versions
       will sort property.

    2. Double-check the TAG setting in debian/rules to be sure it's going
       to retrieve the correct Git tag.

    3. Run debian/rules get-orig-source.  This will generate a tarball
       from the upstream Git tag using git archive, remove the WINNT
       directory, and create a file named openafs_<version>.orig.tar.gz in
       the current directory.

    4. Ensure that you have the OpenAFS upstream Git repository available
       as a remote in the Git repository where you're doing the packaging
       work and it's up to date:

           git remote add openafs git://git.openafs.org/openafs.git
           git fetch openafs

       This will be required to locate the tag for the new upstream

    5. Determine the release tag corresponding to this tarball.  At the
       time of this writing, upstream uses tags in the form:


       for stable and development releases respectively.  <version> is the
       version number with periods replaced by underscores.  This
       convention may change, so double-check with git tag.

    6. Import the upstream source from the tarball with:

           debian/import-upstream <tarball> <upstream-tag> <local-tag>

       where <tarball> is the tarball created by get-orig-source above,
       <upstream-tag> is the corresponding tag from the upstream Git
       repository, and <local-tag> is of the form upstream/<version> where
       <version> is the non-Debian portion of the package version number.
       (In other words, including any tildes, but not the dash and the
       Debian revision.)

    7. Commit the tarball to the repository with pristine-tar, using the
       new local tag as the reference:

           pristine-tar commit <tarball> <local-tag>

    8. Merge the new upstream source into the master branch:

           git checkout master
           git merge <local-tag>

       where <local-tag> is the tag you used above.  You can also just
       merge with the upstream branch; either is equivalent.

    9. Flesh out the changelog entry for the new version with a summary of
       what changed in that release, and continue as normal with Debian

Pulling Upstream Changes

    Upstream releases, particularly stable releases, are relatively
    infrequent, so it's often desirable to pull upstream changes from the
    stable branch into the Debian package.  This should always be done
    using git cherry-pick -x so that we can use git cherry to see which
    changes on the stable branch have not been picked up.

    The procedure is therefore:

    1. Identify the hash of the commit that you want to pull up using git
       log or other information.

    2. git cherry-pick -x <hash>.  If the cherry-pick fails and you have
       to manually do a merge, follow the instructions to use -c to keep
       the original commit message as a starting point, but *also*
       manually add a line like:

           (cherry picked from commit <hash>)

       to the changelog entry where <hash> is the full hash of the
       upstream commit.  Note that the upstream commits on the stable
       branch will generally already have a line like this from upstream's
       cherry-pick.  This will be a second line.

    3. Add a changelog entry and commit it separately.  Use the following
       convention for changelog entries for cherry-picks:

           * Apply upstream deltas:
             - [<hash>] <title>
             - ...

       where <hash> is the first eight characters of the upstream commit
       hash and <title> is the first line of the upstream commit message,
       edited as necessary to keep the length of the changelog lines

Russ Allbery (rra@debian.org)               <http://www.eyrie.org/~eagle/>

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