blob: 6760b10828908e03c129290fd5c9862bca4fffc8 [file] [log] [blame]
Andrew Geisslerc9f78652020-09-18 14:11:35 -05001.. SPDX-License-Identifier: CC-BY-2.5
2
3=====================
4File Download Support
5=====================
6
7|
8
9BitBake's fetch module is a standalone piece of library code that deals
10with the intricacies of downloading source code and files from remote
11systems. Fetching source code is one of the cornerstones of building
12software. As such, this module forms an important part of BitBake.
13
14The current fetch module is called "fetch2" and refers to the fact that
15it is the second major version of the API. The original version is
16obsolete and has been removed from the codebase. Thus, in all cases,
17"fetch" refers to "fetch2" in this manual.
18
19The Download (Fetch)
20====================
21
22BitBake takes several steps when fetching source code or files. The
23fetcher codebase deals with two distinct processes in order: obtaining
24the files from somewhere (cached or otherwise) and then unpacking those
25files into a specific location and perhaps in a specific way. Getting
26and unpacking the files is often optionally followed by patching.
27Patching, however, is not covered by this module.
28
29The code to execute the first part of this process, a fetch, looks
30something like the following: ::
31
32 src_uri = (d.getVar('SRC_URI') or "").split()
33 fetcher = bb.fetch2.Fetch(src_uri, d)
34 fetcher.download()
35
36This code sets up an instance of the fetch class. The instance uses a
37space-separated list of URLs from the :term:`SRC_URI`
38variable and then calls the ``download`` method to download the files.
39
40The instantiation of the fetch class is usually followed by: ::
41
42 rootdir = l.getVar('WORKDIR')
43 fetcher.unpack(rootdir)
44
45This code unpacks the downloaded files to the specified by ``WORKDIR``.
46
47.. note::
48
49 For convenience, the naming in these examples matches the variables
50 used by OpenEmbedded. If you want to see the above code in action,
51 examine the OpenEmbedded class file ``base.bbclass``
52 .
53
54The ``SRC_URI`` and ``WORKDIR`` variables are not hardcoded into the
55fetcher, since those fetcher methods can be (and are) called with
56different variable names. In OpenEmbedded for example, the shared state
57(sstate) code uses the fetch module to fetch the sstate files.
58
59When the ``download()`` method is called, BitBake tries to resolve the
60URLs by looking for source files in a specific search order:
61
62- *Pre-mirror Sites:* BitBake first uses pre-mirrors to try and find
63 source files. These locations are defined using the
64 :term:`PREMIRRORS` variable.
65
66- *Source URI:* If pre-mirrors fail, BitBake uses the original URL (e.g
67 from ``SRC_URI``).
68
69- *Mirror Sites:* If fetch failures occur, BitBake next uses mirror
70 locations as defined by the :term:`MIRRORS` variable.
71
72For each URL passed to the fetcher, the fetcher calls the submodule that
73handles that particular URL type. This behavior can be the source of
74some confusion when you are providing URLs for the ``SRC_URI`` variable.
75Consider the following two URLs: ::
76
77 http://git.yoctoproject.org/git/poky;protocol=git
78 git://git.yoctoproject.org/git/poky;protocol=http
79
80In the former case, the URL is passed to the ``wget`` fetcher, which does not
81understand "git". Therefore, the latter case is the correct form since the Git
82fetcher does know how to use HTTP as a transport.
83
84Here are some examples that show commonly used mirror definitions: ::
85
86 PREMIRRORS ?= "\
87 bzr://.*/.\* http://somemirror.org/sources/ \\n \
88 cvs://.*/.\* http://somemirror.org/sources/ \\n \
89 git://.*/.\* http://somemirror.org/sources/ \\n \
90 hg://.*/.\* http://somemirror.org/sources/ \\n \
91 osc://.*/.\* http://somemirror.org/sources/ \\n \
92 p4://.*/.\* http://somemirror.org/sources/ \\n \
93 svn://.*/.\* http://somemirror.org/sources/ \\n"
94
95 MIRRORS =+ "\
96 ftp://.*/.\* http://somemirror.org/sources/ \\n \
97 http://.*/.\* http://somemirror.org/sources/ \\n \
98 https://.*/.\* http://somemirror.org/sources/ \\n"
99
100It is useful to note that BitBake
101supports cross-URLs. It is possible to mirror a Git repository on an
102HTTP server as a tarball. This is what the ``git://`` mapping in the
103previous example does.
104
105Since network accesses are slow, BitBake maintains a cache of files
106downloaded from the network. Any source files that are not local (i.e.
107downloaded from the Internet) are placed into the download directory,
108which is specified by the :term:`DL_DIR` variable.
109
110File integrity is of key importance for reproducing builds. For
111non-local archive downloads, the fetcher code can verify SHA-256 and MD5
112checksums to ensure the archives have been downloaded correctly. You can
113specify these checksums by using the ``SRC_URI`` variable with the
114appropriate varflags as follows: ::
115
116 SRC_URI[md5sum] = "value"
117 SRC_URI[sha256sum] = "value"
118
119You can also specify the checksums as
120parameters on the ``SRC_URI`` as shown below: ::
121
122 SRC_URI = "http://example.com/foobar.tar.bz2;md5sum=4a8e0f237e961fd7785d19d07fdb994d"
123
124If multiple URIs exist, you can specify the checksums either directly as
125in the previous example, or you can name the URLs. The following syntax
126shows how you name the URIs: ::
127
128 SRC_URI = "http://example.com/foobar.tar.bz2;name=foo"
129 SRC_URI[foo.md5sum] = 4a8e0f237e961fd7785d19d07fdb994d
130
131After a file has been downloaded and
132has had its checksum checked, a ".done" stamp is placed in ``DL_DIR``.
133BitBake uses this stamp during subsequent builds to avoid downloading or
134comparing a checksum for the file again.
135
136.. note::
137
138 It is assumed that local storage is safe from data corruption. If
139 this were not the case, there would be bigger issues to worry about.
140
141If :term:`BB_STRICT_CHECKSUM` is set, any
142download without a checksum triggers an error message. The
143:term:`BB_NO_NETWORK` variable can be used to
144make any attempted network access a fatal error, which is useful for
145checking that mirrors are complete as well as other things.
146
147.. _bb-the-unpack:
148
149The Unpack
150==========
151
152The unpack process usually immediately follows the download. For all
153URLs except Git URLs, BitBake uses the common ``unpack`` method.
154
155A number of parameters exist that you can specify within the URL to
156govern the behavior of the unpack stage:
157
158- *unpack:* Controls whether the URL components are unpacked. If set to
159 "1", which is the default, the components are unpacked. If set to
160 "0", the unpack stage leaves the file alone. This parameter is useful
161 when you want an archive to be copied in and not be unpacked.
162
163- *dos:* Applies to ``.zip`` and ``.jar`` files and specifies whether
164 to use DOS line ending conversion on text files.
165
166- *basepath:* Instructs the unpack stage to strip the specified
167 directories from the source path when unpacking.
168
169- *subdir:* Unpacks the specific URL to the specified subdirectory
170 within the root directory.
171
172The unpack call automatically decompresses and extracts files with ".Z",
173".z", ".gz", ".xz", ".zip", ".jar", ".ipk", ".rpm". ".srpm", ".deb" and
174".bz2" extensions as well as various combinations of tarball extensions.
175
176As mentioned, the Git fetcher has its own unpack method that is
177optimized to work with Git trees. Basically, this method works by
178cloning the tree into the final directory. The process is completed
179using references so that there is only one central copy of the Git
180metadata needed.
181
182.. _bb-fetchers:
183
184Fetchers
185========
186
187As mentioned earlier, the URL prefix determines which fetcher submodule
188BitBake uses. Each submodule can support different URL parameters, which
189are described in the following sections.
190
191.. _local-file-fetcher:
192
193Local file fetcher (``file://``)
194--------------------------------
195
196This submodule handles URLs that begin with ``file://``. The filename
197you specify within the URL can be either an absolute or relative path to
198a file. If the filename is relative, the contents of the
199:term:`FILESPATH` variable is used in the same way
200``PATH`` is used to find executables. If the file cannot be found, it is
201assumed that it is available in :term:`DL_DIR` by the
202time the ``download()`` method is called.
203
204If you specify a directory, the entire directory is unpacked.
205
206Here are a couple of example URLs, the first relative and the second
207absolute: ::
208
209 SRC_URI = "file://relativefile.patch"
210 SRC_URI = "file:///Users/ich/very_important_software"
211
212.. _http-ftp-fetcher:
213
214HTTP/FTP wget fetcher (``http://``, ``ftp://``, ``https://``)
215-------------------------------------------------------------
216
217This fetcher obtains files from web and FTP servers. Internally, the
218fetcher uses the wget utility.
219
220The executable and parameters used are specified by the
221``FETCHCMD_wget`` variable, which defaults to sensible values. The
222fetcher supports a parameter "downloadfilename" that allows the name of
223the downloaded file to be specified. Specifying the name of the
224downloaded file is useful for avoiding collisions in
225:term:`DL_DIR` when dealing with multiple files that
226have the same name.
227
228Some example URLs are as follows: ::
229
230 SRC_URI = "http://oe.handhelds.org/not_there.aac"
231 SRC_URI = "ftp://oe.handhelds.org/not_there_as_well.aac"
232 SRC_URI = "ftp://you@oe.handhelds.org/home/you/secret.plan"
233
234.. note::
235
236 Because URL parameters are delimited by semi-colons, this can
237 introduce ambiguity when parsing URLs that also contain semi-colons,
238 for example:
239 ::
240
241 SRC_URI = "http://abc123.org/git/?p=gcc/gcc.git;a=snapshot;h=a5dd47"
242
243
244 Such URLs should should be modified by replacing semi-colons with '&'
245 characters:
246 ::
247
248 SRC_URI = "http://abc123.org/git/?p=gcc/gcc.git&a=snapshot&h=a5dd47"
249
250
251 In most cases this should work. Treating semi-colons and '&' in
252 queries identically is recommended by the World Wide Web Consortium
253 (W3C). Note that due to the nature of the URL, you may have to
254 specify the name of the downloaded file as well:
255 ::
256
257 SRC_URI = "http://abc123.org/git/?p=gcc/gcc.git&a=snapshot&h=a5dd47;downloadfilename=myfile.bz2"
258
259
260.. _cvs-fetcher:
261
262CVS fetcher (``(cvs://``)
263-------------------------
264
265This submodule handles checking out files from the CVS version control
266system. You can configure it using a number of different variables:
267
268- :term:`FETCHCMD_cvs <FETCHCMD>`: The name of the executable to use when running
269 the ``cvs`` command. This name is usually "cvs".
270
271- :term:`SRCDATE`: The date to use when fetching the CVS source code. A
272 special value of "now" causes the checkout to be updated on every
273 build.
274
275- :term:`CVSDIR`: Specifies where a temporary
276 checkout is saved. The location is often ``DL_DIR/cvs``.
277
278- CVS_PROXY_HOST: The name to use as a "proxy=" parameter to the
279 ``cvs`` command.
280
281- CVS_PROXY_PORT: The port number to use as a "proxyport="
282 parameter to the ``cvs`` command.
283
284As well as the standard username and password URL syntax, you can also
285configure the fetcher with various URL parameters:
286
287The supported parameters are as follows:
288
289- *"method":* The protocol over which to communicate with the CVS
290 server. By default, this protocol is "pserver". If "method" is set to
291 "ext", BitBake examines the "rsh" parameter and sets ``CVS_RSH``. You
292 can use "dir" for local directories.
293
294- *"module":* Specifies the module to check out. You must supply this
295 parameter.
296
297- *"tag":* Describes which CVS TAG should be used for the checkout. By
298 default, the TAG is empty.
299
300- *"date":* Specifies a date. If no "date" is specified, the
301 :term:`SRCDATE` of the configuration is used to
302 checkout a specific date. The special value of "now" causes the
303 checkout to be updated on every build.
304
305- *"localdir":* Used to rename the module. Effectively, you are
306 renaming the output directory to which the module is unpacked. You
307 are forcing the module into a special directory relative to
308 :term:`CVSDIR`.
309
310- *"rsh":* Used in conjunction with the "method" parameter.
311
312- *"scmdata":* Causes the CVS metadata to be maintained in the tarball
313 the fetcher creates when set to "keep". The tarball is expanded into
314 the work directory. By default, the CVS metadata is removed.
315
316- *"fullpath":* Controls whether the resulting checkout is at the
317 module level, which is the default, or is at deeper paths.
318
319- *"norecurse":* Causes the fetcher to only checkout the specified
320 directory with no recurse into any subdirectories.
321
322- *"port":* The port to which the CVS server connects.
323
324Some example URLs are as follows: ::
325
326 SRC_URI = "cvs://CVSROOT;module=mymodule;tag=some-version;method=ext"
327 SRC_URI = "cvs://CVSROOT;module=mymodule;date=20060126;localdir=usethat"
328
329.. _svn-fetcher:
330
331Subversion (SVN) Fetcher (``svn://``)
332-------------------------------------
333
334This fetcher submodule fetches code from the Subversion source control
335system. The executable used is specified by ``FETCHCMD_svn``, which
336defaults to "svn". The fetcher's temporary working directory is set by
337:term:`SVNDIR`, which is usually ``DL_DIR/svn``.
338
339The supported parameters are as follows:
340
341- *"module":* The name of the svn module to checkout. You must provide
342 this parameter. You can think of this parameter as the top-level
343 directory of the repository data you want.
344
345- *"path_spec":* A specific directory in which to checkout the
346 specified svn module.
347
348- *"protocol":* The protocol to use, which defaults to "svn". If
349 "protocol" is set to "svn+ssh", the "ssh" parameter is also used.
350
351- *"rev":* The revision of the source code to checkout.
352
Andrew Geisslerf0343792020-11-18 10:42:21 -0600353- *"scmdata":* Causes the ".svn" directories to be available during
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500354 compile-time when set to "keep". By default, these directories are
355 removed.
356
357- *"ssh":* An optional parameter used when "protocol" is set to
358 "svn+ssh". You can use this parameter to specify the ssh program used
359 by svn.
360
361- *"transportuser":* When required, sets the username for the
362 transport. By default, this parameter is empty. The transport
363 username is different than the username used in the main URL, which
364 is passed to the subversion command.
365
366Following are three examples using svn: ::
367
368 SRC_URI = "svn://myrepos/proj1;module=vip;protocol=http;rev=667"
369 SRC_URI = "svn://myrepos/proj1;module=opie;protocol=svn+ssh"
370 SRC_URI = "svn://myrepos/proj1;module=trunk;protocol=http;path_spec=${MY_DIR}/proj1"
371
372.. _git-fetcher:
373
374Git Fetcher (``git://``)
375------------------------
376
377This fetcher submodule fetches code from the Git source control system.
378The fetcher works by creating a bare clone of the remote into
379:term:`GITDIR`, which is usually ``DL_DIR/git2``. This
380bare clone is then cloned into the work directory during the unpack
381stage when a specific tree is checked out. This is done using alternates
382and by reference to minimize the amount of duplicate data on the disk
383and make the unpack process fast. The executable used can be set with
384``FETCHCMD_git``.
385
386This fetcher supports the following parameters:
387
388- *"protocol":* The protocol used to fetch the files. The default is
389 "git" when a hostname is set. If a hostname is not set, the Git
390 protocol is "file". You can also use "http", "https", "ssh" and
391 "rsync".
392
393- *"nocheckout":* Tells the fetcher to not checkout source code when
394 unpacking when set to "1". Set this option for the URL where there is
395 a custom routine to checkout code. The default is "0".
396
397- *"rebaseable":* Indicates that the upstream Git repository can be
398 rebased. You should set this parameter to "1" if revisions can become
399 detached from branches. In this case, the source mirror tarball is
400 done per revision, which has a loss of efficiency. Rebasing the
401 upstream Git repository could cause the current revision to disappear
402 from the upstream repository. This option reminds the fetcher to
403 preserve the local cache carefully for future use. The default value
404 for this parameter is "0".
405
406- *"nobranch":* Tells the fetcher to not check the SHA validation for
407 the branch when set to "1". The default is "0". Set this option for
408 the recipe that refers to the commit that is valid for a tag instead
409 of the branch.
410
411- *"bareclone":* Tells the fetcher to clone a bare clone into the
412 destination directory without checking out a working tree. Only the
413 raw Git metadata is provided. This parameter implies the "nocheckout"
414 parameter as well.
415
416- *"branch":* The branch(es) of the Git tree to clone. If unset, this
417 is assumed to be "master". The number of branch parameters much match
418 the number of name parameters.
419
420- *"rev":* The revision to use for the checkout. The default is
421 "master".
422
423- *"tag":* Specifies a tag to use for the checkout. To correctly
424 resolve tags, BitBake must access the network. For that reason, tags
425 are often not used. As far as Git is concerned, the "tag" parameter
426 behaves effectively the same as the "rev" parameter.
427
428- *"subpath":* Limits the checkout to a specific subpath of the tree.
429 By default, the whole tree is checked out.
430
431- *"destsuffix":* The name of the path in which to place the checkout.
432 By default, the path is ``git/``.
433
434- *"usehead":* Enables local ``git://`` URLs to use the current branch
435 HEAD as the revision for use with ``AUTOREV``. The "usehead"
436 parameter implies no branch and only works when the transfer protocol
437 is ``file://``.
438
439Here are some example URLs: ::
440
441 SRC_URI = "git://git.oe.handhelds.org/git/vip.git;tag=version-1"
442 SRC_URI = "git://git.oe.handhelds.org/git/vip.git;protocol=http"
443
444.. _gitsm-fetcher:
445
446Git Submodule Fetcher (``gitsm://``)
447------------------------------------
448
449This fetcher submodule inherits from the :ref:`Git
450fetcher<bitbake-user-manual/bitbake-user-manual-fetching:git fetcher
451(\`\`git://\`\`)>` and extends that fetcher's behavior by fetching a
452repository's submodules. :term:`SRC_URI` is passed to the Git fetcher as
453described in the :ref:`bitbake-user-manual/bitbake-user-manual-fetching:git
454fetcher (\`\`git://\`\`)` section.
455
456.. note::
457
458 You must clean a recipe when switching between '``git://``' and
459 '``gitsm://``' URLs.
460
461 The Git Submodules fetcher is not a complete fetcher implementation.
462 The fetcher has known issues where it does not use the normal source
463 mirroring infrastructure properly. Further, the submodule sources it
464 fetches are not visible to the licensing and source archiving
465 infrastructures.
466
467.. _clearcase-fetcher:
468
469ClearCase Fetcher (``ccrc://``)
470-------------------------------
471
472This fetcher submodule fetches code from a
473`ClearCase <http://en.wikipedia.org/wiki/Rational_ClearCase>`__
474repository.
475
476To use this fetcher, make sure your recipe has proper
477:term:`SRC_URI`, :term:`SRCREV`, and
478:term:`PV` settings. Here is an example: ::
479
480 SRC_URI = "ccrc://cc.example.org/ccrc;vob=/example_vob;module=/example_module"
481 SRCREV = "EXAMPLE_CLEARCASE_TAG"
482 PV = "${@d.getVar("SRCREV", False).replace("/", "+")}"
483
484The fetcher uses the ``rcleartool`` or
485``cleartool`` remote client, depending on which one is available.
486
487Following are options for the ``SRC_URI`` statement:
488
489- *vob*: The name, which must include the prepending "/" character,
490 of the ClearCase VOB. This option is required.
491
492- *module*: The module, which must include the prepending "/"
493 character, in the selected VOB.
494
495 .. note::
496
497 The module and vob options are combined to create the load rule in the
498 view config spec. As an example, consider the vob and module values from
499 the SRC_URI statement at the start of this section. Combining those values
500 results in the following: ::
501
502 load /example_vob/example_module
503
504- *proto*: The protocol, which can be either ``http`` or ``https``.
505
506By default, the fetcher creates a configuration specification. If you
507want this specification written to an area other than the default, use
508the ``CCASE_CUSTOM_CONFIG_SPEC`` variable in your recipe to define where
509the specification is written.
510
511.. note::
512
513 the SRCREV loses its functionality if you specify this variable. However,
514 SRCREV is still used to label the archive after a fetch even though it does
515 not define what is fetched.
516
517Here are a couple of other behaviors worth mentioning:
518
519- When using ``cleartool``, the login of ``cleartool`` is handled by
520 the system. The login require no special steps.
521
522- In order to use ``rcleartool`` with authenticated users, an
523 "rcleartool login" is necessary before using the fetcher.
524
525.. _perforce-fetcher:
526
527Perforce Fetcher (``p4://``)
528----------------------------
529
530This fetcher submodule fetches code from the
531`Perforce <https://www.perforce.com/>`__ source control system. The
532executable used is specified by ``FETCHCMD_p4``, which defaults to "p4".
533The fetcher's temporary working directory is set by
534:term:`P4DIR`, which defaults to "DL_DIR/p4".
535The fetcher does not make use of a perforce client, instead it
536relies on ``p4 files`` to retrieve a list of
537files and ``p4 print`` to transfer the content
538of those files locally.
539
540To use this fetcher, make sure your recipe has proper
541:term:`SRC_URI`, :term:`SRCREV`, and
542:term:`PV` values. The p4 executable is able to use the
543config file defined by your system's ``P4CONFIG`` environment variable
544in order to define the Perforce server URL and port, username, and
545password if you do not wish to keep those values in a recipe itself. If
546you choose not to use ``P4CONFIG``, or to explicitly set variables that
547``P4CONFIG`` can contain, you can specify the ``P4PORT`` value, which is
548the server's URL and port number, and you can specify a username and
549password directly in your recipe within ``SRC_URI``.
550
551Here is an example that relies on ``P4CONFIG`` to specify the server URL
552and port, username, and password, and fetches the Head Revision: ::
553
554 SRC_URI = "p4://example-depot/main/source/..."
555 SRCREV = "${AUTOREV}"
556 PV = "p4-${SRCPV}"
557 S = "${WORKDIR}/p4"
558
559Here is an example that specifies the server URL and port, username, and
560password, and fetches a Revision based on a Label: ::
561
562 P4PORT = "tcp:p4server.example.net:1666"
563 SRC_URI = "p4://user:passwd@example-depot/main/source/..."
564 SRCREV = "release-1.0"
565 PV = "p4-${SRCPV}"
566 S = "${WORKDIR}/p4"
567
568.. note::
569
570 You should always set S to "${WORKDIR}/p4" in your recipe.
571
572By default, the fetcher strips the depot location from the local file paths. In
573the above example, the content of ``example-depot/main/source/`` will be placed
574in ``${WORKDIR}/p4``. For situations where preserving parts of the remote depot
575paths locally is desirable, the fetcher supports two parameters:
576
577- *"module":*
578 The top-level depot location or directory to fetch. The value of this
579 parameter can also point to a single file within the depot, in which case
580 the local file path will include the module path.
581- *"remotepath":*
582 When used with the value "``keep``", the fetcher will mirror the full depot
583 paths locally for the specified location, even in combination with the
584 ``module`` parameter.
585
586Here is an example use of the the ``module`` parameter: ::
587
588 SRC_URI = "p4://user:passwd@example-depot/main;module=source/..."
589
590In this case, the content of the top-level directory ``source/`` will be fetched
591to ``${P4DIR}``, including the directory itself. The top-level directory will
592be accesible at ``${P4DIR}/source/``.
593
594Here is an example use of the the ``remotepath`` parameter: ::
595
596 SRC_URI = "p4://user:passwd@example-depot/main;module=source/...;remotepath=keep"
597
598In this case, the content of the top-level directory ``source/`` will be fetched
599to ``${P4DIR}``, but the complete depot paths will be mirrored locally. The
600top-level directory will be accessible at
601``${P4DIR}/example-depot/main/source/``.
602
603.. _repo-fetcher:
604
605Repo Fetcher (``repo://``)
606--------------------------
607
608This fetcher submodule fetches code from ``google-repo`` source control
609system. The fetcher works by initiating and syncing sources of the
610repository into :term:`REPODIR`, which is usually
611``${DL_DIR}/repo``.
612
613This fetcher supports the following parameters:
614
615- *"protocol":* Protocol to fetch the repository manifest (default:
616 git).
617
618- *"branch":* Branch or tag of repository to get (default: master).
619
620- *"manifest":* Name of the manifest file (default: ``default.xml``).
621
622Here are some example URLs: ::
623
624 SRC_URI = "repo://REPOROOT;protocol=git;branch=some_branch;manifest=my_manifest.xml"
625 SRC_URI = "repo://REPOROOT;protocol=file;branch=some_branch;manifest=my_manifest.xml"
626
627Other Fetchers
628--------------
629
630Fetch submodules also exist for the following:
631
632- Bazaar (``bzr://``)
633
634- Mercurial (``hg://``)
635
636- npm (``npm://``)
637
638- OSC (``osc://``)
639
640- Secure FTP (``sftp://``)
641
642- Secure Shell (``ssh://``)
643
644- Trees using Git Annex (``gitannex://``)
645
646No documentation currently exists for these lesser used fetcher
647submodules. However, you might find the code helpful and readable.
648
649Auto Revisions
650==============
651
652We need to document ``AUTOREV`` and ``SRCREV_FORMAT`` here.