using dgit. This git history is stored in a canonical location known
as
.B dgit-repos
-which lives outside the Debian archive (currently, on Alioth).
+which lives on a dedicated git server.
+
+git branches suitable for use with dgit
+can be edited directly in git,
+and used directly for building binary packages.
+They can be shared using all conventional means for sharing git
+branches.
+It is not necessary to use dgit to work with dgitish git branches.
+However, dgit is (usually) needed in order to convert to or from
+Debian-format source packages.
+.SH SEE ALSO
+.TP
+\fBdgit\fP(1)
+Reference manual and documentation catalogue.
+.TP
+\fBdgit-*\fB(7)
+Tutorials and workflow guides. See dgit(1) for a list.
.SH MODEL
You may use any suitable git workflow with dgit, provided you
satisfy dgit's requirements:
normally the dgit-repos repo for the package will be accessible via
the remote name `origin'.
-dgit push will also (by default) make signed tags called
-.BI debian/ version
-and push them to dgit-repos, but nothing depends on these tags
-existing.
-
-dgit push can operate on any commit which is a descendant of the
-current dgit/suite tip in dgit-repos.
+dgit push will also make signed tags called
+.BI archive/debian/ version
+(with version encoded a la DEP-14)
+and push them to dgit-repos. These are used at the
+server to authenticate pushes.
Uploads made by dgit contain an additional field
.B Dgit
in the source package .dsc. (This is added by dgit push.)
-This specifies a commit (an ancestor of the dgit/suite
-branch) whose tree is identical to the unpacked source upload.
+This specifies: a commit (an ancestor of the dgit/suite
+branch) whose tree is identical to the unpacked source upload;
+the distro to which the upload was made;
+a tag name which can be used to fetch the git commits;
+and
+a url to use as a hint for the dgit git server for that distro.
Uploads not made by dgit are represented in git by commits which are
synthesised by dgit. The tree of each such commit corresponds to the
-unpacked source; there is an origin commit with the contents, and a
-psuedo-merge from last known upload - that is, from the contents of
+unpacked source; there is a
+commit with the contents,
+and a
+pseudo-merge from last known upload - that is, from the contents of
the dgit/suite branch.
+Depending on the source package format,
+the contents commit may have a more complex structure,
+but ultimately it will be a convergence of stubby branches
+from origin commits representing the components of the source package.
-dgit expects repos that it works with to have a
+dgit expects trees that it works with to have a
.B dgit
-remote. This refers to the well-known dgit-repos location
-(currently, the dgit-repos project on Alioth). dgit fetch updates
-the remote tracking branch for dgit/suite.
+(pseudo) remote. This refers to the dgit-created git view of
+the corresponding archive.
+
+The dgit archive tracking view is synthesised locally,
+on demand,
+by each copy of dgit.
+The tracking view is always a descendant of the
+dgit-repos suite branch (if one exists),
+but may be ahead of it if uploads have been done without dgit.
+The archive tracking view is always fast forwarding within
+each suite.
+
+dgit push can operate on any commit which is a descendant of
+the suite tracking branch.
-dgit does not (currently) represent the orig tarball(s) in git. The
+dgit does not make a systematic record of
+its imports of orig tarball(s).
+So it does not work by finding git tags or branches
+referring to orig tarball(s).
+The
orig tarballs are downloaded (by dgit clone) into the parent
directory, as with a traditional (non-gitish) dpkg-source workflow.
You need to retain these tarballs in the parent directory for dgit
build and dgit push.
+(They are not needed for purely-git-based workflows.)
-dgit repositories could be cloned with standard (git) methods. The
-only exception is that for sourcefull builds / uploads the orig
-tarball(s) need to be present in the parent directory.
+dgit repositories could be cloned with standard (git) methods.
+However,
+the dgit repositories do not contain uploads not made with dgit.
+And
+for sourceful builds / uploads the orig
+tarball(s) will need to be present in the parent directory.
-To a user looking at the archive, changes pushed using dgit look like
+To a user looking at the archive, changes pushed
+in a simple NMU
+using dgit look like
+reasonable
changes made in an NMU: in a `3.0 (quilt)' package the delta from the
-previous upload is recorded in a new patch constructed by dpkg-source.
+previous upload is recorded in new patch(es) constructed by dpkg-source.
+.SH COMBINED SUITES
+dgit can synthesize a combined view of several underlying suites.
+This is requested by specifying, for
+.I suite,
+a comma-separated list:
+.IP
+.IR mainsuite \fB,\fR subsuite ...
+.LP
+This facility is available with dgit clone, fetch and pull, only.
+
+dgit will fetch the same package from each specified underlying suite,
+separately (as if with dgit fetch).
+dgit will then generate a pseudomerge commit
+on the tracking branch
+.BI remotes/dgit/dgit/ suite
+which has the tip of each of the underlying suites
+as an ancestor,
+and which contains the same as the suite which
+has the highest version of the package.
+
+The package must exist in mainsuite,
+but need not exist in the subsuites.
+
+If a specified subsuite starts with
+.B -
+then mainsuite is prepended.
+
+So, for example,
+.B stable,-security
+means to look for the package in stable, and stable-security,
+taking whichever is newer.
+If stable is currently jessie,
+dgit clone would leave you on the branch
+.BR dgit/jessie,-security .
+
+Combined suites are not supported by the dgit build operations.
+This is because those options are intended for building for
+uploading source packages,
+and look in the changelog to find the relevant suite.
+It does not make sense to name a dgit-synthesised combined suite
+in a changelog,
+or to try to upload to it.
+
+When using this facility, it is important to always specify the
+same suites in the same order:
+dgit will not be make a coherent fast-forwarding history
+view otherwise.
+
+The history generated by this feature is not normally suitable
+for merging back into upstreams,
+as it necessarily contains unattractive pseudomerges.
+.SH LIMITATIONS
+Because the synthesis
+of the suite tracking branches
+is done locally based only on the current archive state,
+it will not necessarily see every upload
+not done with dgit.
+Also, different versions of dgit
+(or the software it calls)
+might import the same .dscs differently
+(although we try to minimise this).
+As a consequence, the dgit tracking views of the same
+suite, made by different instances of dgit, may vary.
+They will have the same contents, but may have different history.
+
+There is no uniform linkage between the tracking branches for
+different suites.
+The Debian infrastructure
+does not do any automatic import of uploads made without dgit.
+It would be possible for a distro's infrastructure to do this;
+in that case,
+different dgit client instances
+would see exactly the same history.
+
+There has been no bulk import of historical uploads into
+Debian's dgit infrastructure.
+To do this it would be necessary to decide whether to
+import existing vcs history
+(which might not be faithful to dgit's invariants)
+or previous non-Dgit uploads
+(which would not provide a very rich history).
+
+git represents only file executability.
+git does not represent empty directories,
+or any leaf objects other than plain files and symlinks.
+The behaviour of Debian source package formats
+on objects with unusual permissions is complicated.
+Some pathological Debian source packages will no longer build
+if empty directories are pruned
+(or if other things not reproduced by git are changed).
+Such sources cannot be worked with properly in git,
+and therefore not with dgit either.
.SH READ-ONLY DISTROS
Distros which do not maintain a set of dgit history git repositories
can still be used in a read-only mode with dgit. Currently Ubuntu
is configured this way.
+.SH GITATTRIBUTES
+git has features which can automatically transform files
+as they are being copied between the working tree
+and the git history.
+The attributes can be specified in the source tree itself,
+in
+.BR .gitattributes .
+See \fBgitattributes\fP(5).
+
+These transformations are context-sensitive
+and not, in general, reversible,
+so dgit operates on the principle that
+the dgit git history contains the actual contents of the package.
+(When dgit is manipulating a .dsc,
+it does so in a private area,
+where the transforming gitattributes are defused,
+to achieve this.)
+
+If transforming gitattributes are used,
+they can cause trouble,
+because the working tree files can differ from
+the git revision history
+(and therefore from the source packages).
+dgit warns if it finds a .gitattributes file
+(in a package being fetched or imported),
+unless the transforming gitattributes have been defused.
+
+dgit clone
+and dgit setup-new-tree
+disable transforming gitattributes
+by default,
+by creating a suitable .git/info/attributes.
+See
+.B dgit setup-new-tree
+and
+.B dgit setup-gitattributes
+in dgit(1).
.SH PACKAGE SOURCE FORMATS
If you are not the maintainer, you do not need to worry about the
source format of the package. You can just make changes as you like
in git. If the package is a `3.0 (quilt)' package, the patch stack
will usually not be represented in the git history.
+.SH FILE EXECUTABILITY
+Debian source package formats
+do not always faithfully reproduce
+changes to executability.
+But dgit insists that the result of dgit clone is identical
+(as far as git can represent - see Limitations, above)
+to the result of dpkg-source -x.
+
+So files that are executable in your git tree
+must be executable in the result of dpkg-source -x
+(but often aren't).
+If a package has such troublesome files,
+they have to be non-executable in dgit-compatible git branches.
.SH FORMAT 3.0 (QUILT)
For a format `3.0 (quilt)' source package, dgit may have to make a
commit on your current branch to contain metadata used by quilt and
directory (which is used by quilt to record which patches are
applied). If you want to manipulate the patch stack you probably want
to be looking at tools like git-dpm.
-.SH FILES IN THE SOURCE PACKAGE BUT NOT IN GIT
+.SH SPLIT VIEW QUILT MODE
+When working with git branches intended
+for use with the `3.0 (quilt)' source format
+dgit can automatically convert a suitable
+maintainer-provided git branch
+(in one of a variety of formats)
+into a dgit branch.
+
+When a split view mode is engaged
+dgit build commands and
+dgit push
+will, on each invocation,
+convert the user's HEAD into the dgit view,
+so that it can be built and/or uploaded.
+
+dgit push in split view mode will push the dgit view to the dgit
+git server.
+The dgit view is always a descendant of the maintainer view.
+dgit push will also make a maintainer view tag
+according to DEP-14
+and push that to the dgit git server.
+
+Split view mode must be enabled explicitly
+(by the use of the applicable command line options,
+subcommands, or configuration).
+This is because it is not possible to reliably tell
+(for example)
+whether a git tree for a dpkg-source `3.0 (quilt)' package
+is a patches-applied or patches-unapplied tree.
+
+Split view conversions are cached in the ref
+dgit-intern/quilt-cache.
+This should not be manipulated directly.
+.SH FILES IN THE ORIG TARBALL BUT NOT IN GIT - AUTOTOOLS ETC.
This section is mainly of interest to maintainers who want to use dgit
with their existing git history for the Debian package.
As the maintainer you therefore have the following options:
.TP
\(bu
+Delete the files from your git branches,
+and your Debian source packages,
+and carry the deletion as a delta from upstream.
+(With `3.0 (quilt)' this means represeting the deletions as patches.
+You may need to pass --include-removal to dpkg-source --commit,
+or pass corresponding options to other tools.)
+This can make the Debian
+source package less useful for people without Debian build
+infrastructure.
+.TP
+\(bu
Persuade upstream that the source code in their git history and the
source they ship as tarballs should be identical. Of course simply
removing the files from the tarball may make the tarball hard for
spurious changes. This has the advantage that someone who clones
the git repository finds the program just as easy to build as someone
who uses the tarball.
-.TP
-\(bu
-Have separate git branches which do contain the extra files, and after
-regenerating the extra files (whenever you would have to anyway),
-commit the result onto those branches.
-.TP
-\(bu
-Provide source packages which lack the files you don't want
-in git, and arrange for your package build to create them as needed.
-This may mean not using upstream source tarballs and makes the Debian
-source package less useful for people without Debian build
-infrastructure.
.LP
Of course it may also be that the differences are due to build system
bugs, which cause unintended files to end up in the source package.
dgit will notice this and complain. You may have to fix these bugs
before you can unify your existing git history with dgit's.
-.SH SEE ALSO
-\fBdgit\fP(1).
+.LP
+.SH FILES IN THE SOURCE PACKAGE BUT NOT IN GIT - DOCS, BINARIES ETC.
+Some upstream tarballs contain build artifacts which upstream expects
+some users not to want to rebuild (or indeed to find hard to rebuild),
+but which in Debian we always rebuild.
+.LP
+Examples sometimes include crossbuild firmware binaries and
+documentation.
+To avoid problems when building updated source
+packages
+(in particular, to avoid trying to represent as changes in
+the source package uninteresting or perhaps unrepresentable changes
+to such files)
+many maintainers arrange for the package clean target
+to delete these files.
+.LP
+dpkg-source does not
+(with any of the commonly used source formats)
+represent deletion of binaries (outside debian/) present in upstream.
+Thus deleting such files in a dpkg-source working tree does not
+actually result in them being deleted from the source package.
+Thus
+deleting the files in rules clean sweeps this problem under the rug.
+.LP
+However, git does always properly record file deletion.
+Since dgit's
+principle is that the dgit git tree is the same of dpkg-source -x,
+that means that a dgit-compatible git tree always contains these
+files.
+.LP
+For the non-maintainer,
+this can be observed in the following suboptimal occurrences:
+.TP
+\(bu
+The package clean target often deletes these files, making the git
+tree dirty trying to build the source package, etc.
+This can be fixed
+by using
+.BR "dgit -wg" " aka " "--clean=git" ,
+so that the package clean target is never run.
+.TP
+\(bu
+The package build modifies these files, so that builds make the git
+tree dirty.
+This can be worked around by using `git reset --hard'
+after each build
+(or at least before each commit or push).
+.LP
+From the maintainer's point of view,
+the main consequence is that to make a dgit-compatible git branch
+it is necessary to commit these files to git.
+The maintainer has a few additional options for mitigation:
+for example,
+it may be possible for the rules file to arrange to do the
+build in a temporary area, which avoids updating the troublesome
+files;
+they can then be left in the git tree without seeing trouble.
+.SH PROBLEMS WITH PACKAGE CLEAN TARGETS ETC.
+A related problem is other unexpected behaviour by a package's
+.B clean
+target.
+If a package's rules
+modify files which are distributed in the package,
+or simply forget to remove certain files,
+dgit will complain that the tree is dirty.
+.LP
+Again, the solution is to use
+.BR "dgit -wg" " aka " "--clean=git" ,
+which instructs dgit to use git clean instead of the package's
+build target,
+along with perhaps
+.B git reset --hard
+before each build.
+.LP
+This is 100% reliable, but has the downside
+that if you forget to git add or to commit, and then use
+.BR "dgit -wg" " or " "git reset --hard" ,
+your changes may be lost.
~ianmdlvl / dgit.git / blobdiff