1 .TH dgit 7 "" "Debian Project" "dgit"
3 dgit \- principles of operation
6 treats the Debian archive as a version control system, and
7 bidirectionally gateways between the archive and git. The git view of
8 the package can contain the usual upstream git history, and will be
9 augmented by commits representing uploads done by other developers not
10 using dgit. This git history is stored in a canonical location known
13 which lives on a dedicated git server.
15 git branches suitable for use with dgit
16 can be edited directly in git,
17 and used directly for building binary packages.
18 They can be shared using all conventional means for sharing git
20 It is not necessary to use dgit to work with dgitish git branches.
21 However, dgit is (usually) needed in order to convert to or from
22 Debian-format source packages.
26 Reference manual and documentation catalogue.
29 Tutorials and workflow guides. See dgit(1) for a list.
31 You may use any suitable git workflow with dgit, provided you
32 satisfy dgit's requirements:
34 dgit maintains a pseudo-remote called
36 with one branch per suite. This remote cannot be used with
41 repository for each package contains one ref per suite named
42 \fBrefs/dgit/\fR\fIsuite\fR. These should be pushed to only by
43 dgit. They are fast forwarding. Each push on this branch
44 corresponds to an upload (or attempted upload).
46 However, it is perfectly fine to have other branches in dgit-repos;
47 normally the dgit-repos repo for the package will be accessible via
48 the remote name `origin'.
50 dgit push will also make signed tags called
51 .BI archive/debian/ version
52 (with version encoded a la DEP-14)
53 and push them to dgit-repos. These are used at the
54 server to authenticate pushes.
56 Uploads made by dgit contain an additional field
58 in the source package .dsc. (This is added by dgit push.)
59 This specifies: a commit (an ancestor of the dgit/suite
60 branch) whose tree is identical to the unpacked source upload;
61 the distro to which the upload was made;
62 a tag name which can be used to fetch the git commits;
64 a url to use as a hint for the dgit git server for that distro.
66 Uploads not made by dgit are represented in git by commits which are
67 synthesised by dgit. The tree of each such commit corresponds to the
68 unpacked source; there is a
69 commit with the contents,
71 pseudo-merge from last known upload - that is, from the contents of
72 the dgit/suite branch.
73 Depending on the source package format,
74 the contents commit may have a more complex structure,
75 but ultimately it will be a convergence of stubby branches
76 from origin commits representing the components of the source package.
78 dgit expects trees that it works with to have a
80 (pseudo) remote. This refers to the dgit-created git view of
81 the corresponding archive.
83 The dgit archive tracking view is synthesised locally,
86 The tracking view is always a descendant of the
87 dgit-repos suite branch (if one exists),
88 but may be ahead of it if uploads have been done without dgit.
89 The archive tracking view is always fast forwarding within
92 dgit push can operate on any commit which is a descendant of
93 the suite tracking branch.
95 dgit does not make a systematic record of
96 its imports of orig tarball(s).
97 So it does not work by finding git tags or branches
98 referring to orig tarball(s).
100 orig tarballs are downloaded (by dgit clone) into the parent
101 directory, as with a traditional (non-gitish) dpkg-source workflow.
102 You need to retain these tarballs in the parent directory for dgit
104 (They are not needed for purely-git-based workflows.)
106 dgit repositories could be cloned with standard (git) methods.
108 the dgit repositories do not contain uploads not made with dgit.
110 for sourceful builds / uploads the orig
111 tarball(s) will need to be present in the parent directory.
113 To a user looking at the archive, changes pushed
117 changes made in an NMU: in a `3.0 (quilt)' package the delta from the
118 previous upload is recorded in new patch(es) constructed by dpkg-source.
120 dgit can synthesize a combined view of several underlying suites.
121 This is requested by specifying, for
123 a comma-separated list:
125 .IR mainsuite \fB,\fR subsuite ...
127 This facility is available with dgit clone, fetch and pull, only.
129 dgit will fetch the same package from each specified underlying suite,
130 separately (as if with dgit fetch).
131 dgit will then generate a pseudomerge commit
132 on the tracking branch
133 .BI remotes/dgit/dgit/ suite
134 which has the tip of each of the underlying suites
136 and which contains the same as the suite which
137 has the highest version of the package.
139 The package must exist in mainsuite,
140 but need not exist in the subsuites.
142 If a specified subsuite starts with
144 then mainsuite is prepended.
148 means to look for the package in stable, and stable-security,
149 taking whichever is newer.
150 If stable is currently jessie,
151 dgit clone would leave you on the branch
152 .BR dgit/jessie,-security .
154 Combined suites are not supported by the dgit build operations.
155 This is because those options are intended for building for
156 uploading source packages,
157 and look in the changelog to find the relevant suite.
158 It does not make sense to name a dgit-synthesised combined suite
160 or to try to upload to it.
162 When using this facility, it is important to always specify the
163 same suites in the same order:
164 dgit will not be make a coherent fast-forwarding history
167 The history generated by this feature is not normally suitable
168 for merging back into upstreams,
169 as it necessarily contains unattractive pseudomerges.
171 Because the synthesis
172 of the suite tracking branches
173 is done locally based only on the current archive state,
174 it will not necessarily see every upload
176 Also, different versions of dgit
177 (or the software it calls)
178 might import the same .dscs differently
179 (although we try to minimise this).
180 As a consequence, the dgit tracking views of the same
181 suite, made by different instances of dgit, may vary.
182 They will have the same contents, but may have different history.
184 There is no uniform linkage between the tracking branches for
186 The Debian infrastructure
187 does not do any automatic import of uploads made without dgit.
188 It would be possible for a distro's infrastructure to do this;
190 different dgit client instances
191 would see exactly the same history.
193 There has been no bulk import of historical uploads into
194 Debian's dgit infrastructure.
195 To do this it would be necessary to decide whether to
196 import existing vcs history
197 (which might not be faithful to dgit's invariants)
198 or previous non-Dgit uploads
199 (which would not provide a very rich history).
200 .SH READ-ONLY DISTROS
201 Distros which do not maintain a set of dgit history git repositories
202 can still be used in a read-only mode with dgit. Currently Ubuntu
203 is configured this way.
205 git has features which can automatically transform files
206 as they are being copied between the working tree
208 The attributes can be specified in the source tree itself,
211 See \fBgitattributes\fP(5).
213 These transformations are context-sensitive
214 and not, in general, reversible,
215 so dgit operates on the principle that
216 the dgit git history contains the actual contents of the package.
217 (When dgit is manipulating a .dsc,
218 it does so in a private area,
219 where the transforming gitattributes are defused,
222 If transforming gitattributes are used,
223 they can cause trouble,
224 because the working tree files can differ from
225 the git revision history
226 (and therefore from the source packages).
227 dgit warns if it finds a .gitattributes file
228 (in a package being fetched or imported),
229 unless the transforming gitattributes have been defused.
232 and dgit setup-new-tree
233 disable transforming gitattributes
235 by creating a suitable .git/info/attributes.
237 .B dgit setup-new-tree
239 .B dgit setup-gitattributes
241 .SH PACKAGE SOURCE FORMATS
242 If you are not the maintainer, you do not need to worry about the
243 source format of the package. You can just make changes as you like
244 in git. If the package is a `3.0 (quilt)' package, the patch stack
245 will usually not be represented in the git history.
246 .SH FORMAT 3.0 (QUILT)
247 For a format `3.0 (quilt)' source package, dgit may have to make a
248 commit on your current branch to contain metadata used by quilt and
251 This is because `3.0 (quilt)' source format represents the patch stack
252 as files in debian/patches/ actually inside the source tree. This
253 means that, taking the whole tree (as seen by git or ls) (i)
254 dpkg-source cannot represent certain trees, and (ii) packing up a tree
255 in `3.0 (quilt)' and then unpacking it does not always yield the same
258 dgit will automatically work around this for you when building and
259 pushing. The only thing you need to know is that dgit build, sbuild,
260 etc., may make new commits on your HEAD. If you're not a quilt user
261 this commit won't contain any changes to files you care about.
263 You can explicitly request that dgit do just this fixup, by running
266 If you are a quilt user you need to know that dgit's git trees are
267 `patches applied packaging branches' and do not contain the .pc
268 directory (which is used by quilt to record which patches are
269 applied). If you want to manipulate the patch stack you probably want
270 to be looking at tools like git-dpm.
271 .SH SPLIT VIEW QUILT MODE
272 When working with git branches intended
273 for use with the `3.0 (quilt)' source format
274 dgit can automatically convert a suitable
275 maintainer-provided git branch
276 (in one of a variety of formats)
279 When a split view mode is engaged
280 dgit build commands and
282 will, on each invocation,
283 convert the user's HEAD into the dgit view,
284 so that it can be built and/or uploaded.
286 dgit push in split view mode will push the dgit view to the dgit
288 The dgit view is always a descendant of the maintainer view.
289 dgit push will also make a maintainer view tag
291 and push that to the dgit git server.
293 Split view mode must be enabled explicitly
294 (by the use of the applicable command line options,
295 subcommands, or configuration).
296 This is because it is not possible to reliably tell
298 whether a git tree for a dpkg-source `3.0 (quilt)' package
299 is a patches-applied or patches-unapplied tree.
301 Split view conversions are cached in the ref
302 dgit-intern/quilt-cache.
303 This should not be manipulated directly.
304 .SH FILES IN THE ORIG TARBALL BUT NOT IN GIT - AUTOTOOLS ETC.
305 This section is mainly of interest to maintainers who want to use dgit
306 with their existing git history for the Debian package.
308 Some developers like to have an extra-clean git tree which lacks files
309 which are normally found in source tarballs and therefore in Debian
310 source packages. For example, it is conventional to ship ./configure
311 in the source tarball, but some people prefer not to have it present
312 in the git view of their project.
314 dgit requires that the source package unpacks to exactly the same
315 files as are in the git commit on which dgit push operates. So if you
316 just try to dgit push directly from one of these extra-clean git
317 branches, it will fail.
319 As the maintainer you therefore have the following options:
322 Delete the files from your git branches,
323 and your Debian source packages,
324 and carry the deletion as a delta from upstream.
325 (With `3.0 (quilt)' this means represeting the deletions as patches.
326 You may need to pass --include-removal to dpkg-source --commit,
327 or pass corresponding options to other tools.)
328 This can make the Debian
329 source package less useful for people without Debian build
333 Persuade upstream that the source code in their git history and the
334 source they ship as tarballs should be identical. Of course simply
335 removing the files from the tarball may make the tarball hard for
338 One answer is to commit the (maybe autogenerated)
339 files, perhaps with some simple automation to deal with conflicts and
340 spurious changes. This has the advantage that someone who clones
341 the git repository finds the program just as easy to build as someone
342 who uses the tarball.
344 Of course it may also be that the differences are due to build system
345 bugs, which cause unintended files to end up in the source package.
346 dgit will notice this and complain. You may have to fix these bugs
347 before you can unify your existing git history with dgit's.
349 .SH FILES IN THE SOURCE PACKAGE BUT NOT IN GIT - DOCS, BINARIES ETC.
350 Some upstream tarballs contain build artifacts which upstream expects
351 some users not to want to rebuild (or indeed to find hard to rebuild),
352 but which in Debian we always rebuild.
354 Examples sometimes include crossbuild firmware binaries and
356 To avoid problems when building updated source
358 (in particular, to avoid trying to represent as changes in
359 the source package uninteresting or perhaps unrepresentable changes
361 many maintainers arrange for the package clean target
362 to delete these files.
365 (with any of the commonly used source formats)
366 represent deletion of binaries (outside debian/) present in upstream.
367 Thus deleting such files in a dpkg-source working tree does not
368 actually result in them being deleted from the source package.
370 deleting the files in rules clean sweeps this problem under the rug.
372 However, git does always properly record file deletion.
374 principle is that the dgit git tree is the same of dpkg-source -x,
375 that means that a dgit-compatible git tree always contains these
378 For the non-maintainer,
379 this can be observed in the following suboptimal occurrences:
382 The package clean target often deletes these files, making the git
383 tree dirty trying to build the source package, etc.
386 .BR "dgit -wg" " aka " "--clean=git" ,
387 so that the package clean target is never run.
390 The package build modifies these files, so that builds make the git
392 This can be worked around by using `git reset --hard'
394 (or at least before each commit or push).
396 From the maintainer's point of view,
397 the main consequence is that to make a dgit-compatible git branch
398 it is necessary to commit these files to git.
399 The maintainer has a few additional options for mitigation:
401 it may be possible for the rules file to arrange to do the
402 build in a temporary area, which avoids updating the troublesome
404 they can then be left in the git tree without seeing trouble.
405 .SH PROBLEMS WITH PACKAGE CLEAN TARGETS ETC.
406 A related problem is other unexpected behaviour by a package's
410 modify files which are distributed in the package,
411 or simply forget to remove certain files,
412 dgit will complain that the tree is dirty.
414 Again, the solution is to use
415 .BR "dgit -wg" " aka " "--clean=git" ,
416 which instructs dgit to use git clean instead of the package's
422 This is 100% reliable, but has the downside
423 that if you forget to git add or to commit, and then use
424 .BR "dgit -wg" " or " "git reset --hard" ,
425 your changes may be lost.