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1 gitremote-helpers(7)
2 ====================
3
4 NAME
5 ----
6 gitremote-helpers - Helper programs to interact with remote repositories
7
8 SYNOPSIS
9 --------
10 [verse]
11 'git remote-<transport>' <repository> [<URL>]
12
13 DESCRIPTION
14 -----------
15
16 Remote helper programs are normally not used directly by end users,
17 but they are invoked by Git when it needs to interact with remote
18 repositories Git does not support natively. A given helper will
19 implement a subset of the capabilities documented here. When Git
20 needs to interact with a repository using a remote helper, it spawns
21 the helper as an independent process, sends commands to the helper's
22 standard input, and expects results from the helper's standard
23 output. Because a remote helper runs as an independent process from
24 Git, there is no need to re-link Git to add a new helper, nor any
25 need to link the helper with the implementation of Git.
26
27 Every helper must support the "capabilities" command, which Git
28 uses to determine what other commands the helper will accept. Those
29 other commands can be used to discover and update remote refs,
30 transport objects between the object database and the remote repository,
31 and update the local object store.
32
33 Git comes with a "curl" family of remote helpers, that handle various
34 transport protocols, such as 'git-remote-http', 'git-remote-https',
35 'git-remote-ftp' and 'git-remote-ftps'. They implement the capabilities
36 'fetch', 'option', and 'push'.
37
38 INVOCATION
39 ----------
40
41 Remote helper programs are invoked with one or (optionally) two
42 arguments. The first argument specifies a remote repository as in Git;
43 it is either the name of a configured remote or a URL. The second
44 argument specifies a URL; it is usually of the form
45 '<transport>://<address>', but any arbitrary string is possible.
46 The `GIT_DIR` environment variable is set up for the remote helper
47 and can be used to determine where to store additional data or from
48 which directory to invoke auxiliary Git commands.
49
50 When Git encounters a URL of the form '<transport>://<address>', where
51 '<transport>' is a protocol that it cannot handle natively, it
52 automatically invokes 'git remote-<transport>' with the full URL as
53 the second argument. If such a URL is encountered directly on the
54 command line, the first argument is the same as the second, and if it
55 is encountered in a configured remote, the first argument is the name
56 of that remote.
57
58 A URL of the form '<transport>::<address>' explicitly instructs Git to
59 invoke 'git remote-<transport>' with '<address>' as the second
60 argument. If such a URL is encountered directly on the command line,
61 the first argument is '<address>', and if it is encountered in a
62 configured remote, the first argument is the name of that remote.
63
64 Additionally, when a configured remote has `remote.<name>.vcs` set to
65 '<transport>', Git explicitly invokes 'git remote-<transport>' with
66 '<name>' as the first argument. If set, the second argument is
67 `remote.<name>.url`; otherwise, the second argument is omitted.
68
69 INPUT FORMAT
70 ------------
71
72 Git sends the remote helper a list of commands on standard input, one
73 per line. The first command is always the 'capabilities' command, in
74 response to which the remote helper must print a list of the
75 capabilities it supports (see below) followed by a blank line. The
76 response to the capabilities command determines what commands Git uses
77 in the remainder of the command stream.
78
79 The command stream is terminated by a blank line. In some cases
80 (indicated in the documentation of the relevant commands), this blank
81 line is followed by a payload in some other protocol (e.g., the pack
82 protocol), while in others it indicates the end of input.
83
84 Capabilities
85 ~~~~~~~~~~~~
86
87 Each remote helper is expected to support only a subset of commands.
88 The operations a helper supports are declared to Git in the response
89 to the `capabilities` command (see COMMANDS, below).
90
91 In the following, we list all defined capabilities and for
92 each we list which commands a helper with that capability
93 must provide.
94
95 Capabilities for Pushing
96 ^^^^^^^^^^^^^^^^^^^^^^^^
97 'connect'::
98 Can attempt to connect to 'git receive-pack' (for pushing),
99 'git upload-pack', etc for communication using
100 git's native packfile protocol. This
101 requires a bidirectional, full-duplex connection.
102 +
103 Supported commands: 'connect'.
104
105 'stateless-connect'::
106 Experimental; for internal use only.
107 Can attempt to connect to a remote server for communication
108 using git's wire-protocol version 2. See the documentation
109 for the stateless-connect command for more information.
110 +
111 Supported commands: 'stateless-connect'.
112
113 'push'::
114 Can discover remote refs and push local commits and the
115 history leading up to them to new or existing remote refs.
116 +
117 Supported commands: 'list for-push', 'push'.
118
119 'export'::
120 Can discover remote refs and push specified objects from a
121 fast-import stream to remote refs.
122 +
123 Supported commands: 'list for-push', 'export'.
124
125 If a helper advertises 'connect', Git will use it if possible and
126 fall back to another capability if the helper requests so when
127 connecting (see the 'connect' command under COMMANDS).
128 When choosing between 'push' and 'export', Git prefers 'push'.
129 Other frontends may have some other order of preference.
130
131 'no-private-update'::
132 When using the 'refspec' capability, git normally updates the
133 private ref on successful push. This update is disabled when
134 the remote-helper declares the capability 'no-private-update'.
135
136
137 Capabilities for Fetching
138 ^^^^^^^^^^^^^^^^^^^^^^^^^
139 'connect'::
140 Can try to connect to 'git upload-pack' (for fetching),
141 'git receive-pack', etc for communication using the
142 Git's native packfile protocol. This
143 requires a bidirectional, full-duplex connection.
144 +
145 Supported commands: 'connect'.
146
147 'stateless-connect'::
148 Experimental; for internal use only.
149 Can attempt to connect to a remote server for communication
150 using git's wire-protocol version 2. See the documentation
151 for the stateless-connect command for more information.
152 +
153 Supported commands: 'stateless-connect'.
154
155 'fetch'::
156 Can discover remote refs and transfer objects reachable from
157 them to the local object store.
158 +
159 Supported commands: 'list', 'fetch'.
160
161 'import'::
162 Can discover remote refs and output objects reachable from
163 them as a stream in fast-import format.
164 +
165 Supported commands: 'list', 'import'.
166
167 'check-connectivity'::
168 Can guarantee that when a clone is requested, the received
169 pack is self contained and is connected.
170
171 If a helper advertises 'connect', Git will use it if possible and
172 fall back to another capability if the helper requests so when
173 connecting (see the 'connect' command under COMMANDS).
174 When choosing between 'fetch' and 'import', Git prefers 'fetch'.
175 Other frontends may have some other order of preference.
176
177 Miscellaneous capabilities
178 ^^^^^^^^^^^^^^^^^^^^^^^^^^
179
180 'option'::
181 For specifying settings like `verbosity` (how much output to
182 write to stderr) and `depth` (how much history is wanted in the
183 case of a shallow clone) that affect how other commands are
184 carried out.
185
186 'refspec' <refspec>::
187 For remote helpers that implement 'import' or 'export', this capability
188 allows the refs to be constrained to a private namespace, instead of
189 writing to refs/heads or refs/remotes directly.
190 It is recommended that all importers providing the 'import'
191 capability use this. It's mandatory for 'export'.
192 +
193 A helper advertising the capability
194 `refspec refs/heads/*:refs/svn/origin/branches/*`
195 is saying that, when it is asked to `import refs/heads/topic`, the
196 stream it outputs will update the `refs/svn/origin/branches/topic`
197 ref.
198 +
199 This capability can be advertised multiple times. The first
200 applicable refspec takes precedence. The left-hand of refspecs
201 advertised with this capability must cover all refs reported by
202 the list command. If no 'refspec' capability is advertised,
203 there is an implied `refspec *:*`.
204 +
205 When writing remote-helpers for decentralized version control
206 systems, it is advised to keep a local copy of the repository to
207 interact with, and to let the private namespace refs point to this
208 local repository, while the refs/remotes namespace is used to track
209 the remote repository.
210
211 'bidi-import'::
212 This modifies the 'import' capability.
213 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers
214 to retrieve information about blobs and trees that already exist in
215 fast-import's memory. This requires a channel from fast-import to the
216 remote-helper.
217 If it is advertised in addition to "import", Git establishes a pipe from
218 fast-import to the remote-helper's stdin.
219 It follows that Git and fast-import are both connected to the
220 remote-helper's stdin. Because Git can send multiple commands to
221 the remote-helper it is required that helpers that use 'bidi-import'
222 buffer all 'import' commands of a batch before sending data to fast-import.
223 This is to prevent mixing commands and fast-import responses on the
224 helper's stdin.
225
226 'export-marks' <file>::
227 This modifies the 'export' capability, instructing Git to dump the
228 internal marks table to <file> when complete. For details,
229 read up on `--export-marks=<file>` in linkgit:git-fast-export[1].
230
231 'import-marks' <file>::
232 This modifies the 'export' capability, instructing Git to load the
233 marks specified in <file> before processing any input. For details,
234 read up on `--import-marks=<file>` in linkgit:git-fast-export[1].
235
236 'signed-tags'::
237 This modifies the 'export' capability, instructing Git to pass
238 `--signed-tags=verbatim` to linkgit:git-fast-export[1]. In the
239 absence of this capability, Git will use `--signed-tags=warn-strip`.
240
241 'object-format'::
242 This indicates that the helper is able to interact with the remote
243 side using an explicit hash algorithm extension.
244
245
246 COMMANDS
247 --------
248
249 Commands are given by the caller on the helper's standard input, one per line.
250
251 'capabilities'::
252 Lists the capabilities of the helper, one per line, ending
253 with a blank line. Each capability may be preceded with '*',
254 which marks them mandatory for Git versions using the remote
255 helper to understand. Any unknown mandatory capability is a
256 fatal error.
257 +
258 Support for this command is mandatory.
259
260 'list'::
261 Lists the refs, one per line, in the format "<value> <name>
262 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for
263 a symref, ":<keyword> <value>" for a key-value pair, or
264 "?" to indicate that the helper could not get the value of the
265 ref. A space-separated list of attributes follows the name;
266 unrecognized attributes are ignored. The list ends with a
267 blank line.
268 +
269 See REF LIST ATTRIBUTES for a list of currently defined attributes.
270 See REF LIST KEYWORDS for a list of currently defined keywords.
271 +
272 Supported if the helper has the "fetch" or "import" capability.
273
274 'list for-push'::
275 Similar to 'list', except that it is used if and only if
276 the caller wants to the resulting ref list to prepare
277 push commands.
278 A helper supporting both push and fetch can use this
279 to distinguish for which operation the output of 'list'
280 is going to be used, possibly reducing the amount
281 of work that needs to be performed.
282 +
283 Supported if the helper has the "push" or "export" capability.
284
285 'option' <name> <value>::
286 Sets the transport helper option <name> to <value>. Outputs a
287 single line containing one of 'ok' (option successfully set),
288 'unsupported' (option not recognized) or 'error <msg>'
289 (option <name> is supported but <value> is not valid
290 for it). Options should be set before other commands,
291 and may influence the behavior of those commands.
292 +
293 See OPTIONS for a list of currently defined options.
294 +
295 Supported if the helper has the "option" capability.
296
297 'fetch' <sha1> <name>::
298 Fetches the given object, writing the necessary objects
299 to the database. Fetch commands are sent in a batch, one
300 per line, terminated with a blank line.
301 Outputs a single blank line when all fetch commands in the
302 same batch are complete. Only objects which were reported
303 in the output of 'list' with a sha1 may be fetched this way.
304 +
305 Optionally may output a 'lock <file>' line indicating the full path of
306 a file under `$GIT_DIR/objects/pack` which is keeping a pack until
307 refs can be suitably updated. The path must end with `.keep`. This is
308 a mechanism to name a <pack,idx,keep> tuple by giving only the keep
309 component. The kept pack will not be deleted by a concurrent repack,
310 even though its objects may not be referenced until the fetch completes.
311 The `.keep` file will be deleted at the conclusion of the fetch.
312 +
313 If option 'check-connectivity' is requested, the helper must output
314 'connectivity-ok' if the clone is self-contained and connected.
315 +
316 Supported if the helper has the "fetch" capability.
317
318 'push' +<src>:<dst>::
319 Pushes the given local <src> commit or branch to the
320 remote branch described by <dst>. A batch sequence of
321 one or more 'push' commands is terminated with a blank line
322 (if there is only one reference to push, a single 'push' command
323 is followed by a blank line). For example, the following would
324 be two batches of 'push', the first asking the remote-helper
325 to push the local ref 'master' to the remote ref 'master' and
326 the local `HEAD` to the remote 'branch', and the second
327 asking to push ref 'foo' to ref 'bar' (forced update requested
328 by the '+').
329 +
330 ------------
331 push refs/heads/master:refs/heads/master
332 push HEAD:refs/heads/branch
333 \n
334 push +refs/heads/foo:refs/heads/bar
335 \n
336 ------------
337 +
338 Zero or more protocol options may be entered after the last 'push'
339 command, before the batch's terminating blank line.
340 +
341 When the push is complete, outputs one or more 'ok <dst>' or
342 'error <dst> <why>?' lines to indicate success or failure of
343 each pushed ref. The status report output is terminated by
344 a blank line. The option field <why> may be quoted in a C
345 style string if it contains an LF.
346 +
347 Supported if the helper has the "push" capability.
348
349 'import' <name>::
350 Produces a fast-import stream which imports the current value
351 of the named ref. It may additionally import other refs as
352 needed to construct the history efficiently. The script writes
353 to a helper-specific private namespace. The value of the named
354 ref should be written to a location in this namespace derived
355 by applying the refspecs from the "refspec" capability to the
356 name of the ref.
357 +
358 Especially useful for interoperability with a foreign versioning
359 system.
360 +
361 Just like 'push', a batch sequence of one or more 'import' is
362 terminated with a blank line. For each batch of 'import', the remote
363 helper should produce a fast-import stream terminated by a 'done'
364 command.
365 +
366 Note that if the 'bidi-import' capability is used the complete batch
367 sequence has to be buffered before starting to send data to fast-import
368 to prevent mixing of commands and fast-import responses on the helper's
369 stdin.
370 +
371 Supported if the helper has the "import" capability.
372
373 'export'::
374 Instructs the remote helper that any subsequent input is
375 part of a fast-import stream (generated by 'git fast-export')
376 containing objects which should be pushed to the remote.
377 +
378 Especially useful for interoperability with a foreign versioning
379 system.
380 +
381 The 'export-marks' and 'import-marks' capabilities, if specified,
382 affect this command in so far as they are passed on to 'git
383 fast-export', which then will load/store a table of marks for
384 local objects. This can be used to implement for incremental
385 operations.
386 +
387 Supported if the helper has the "export" capability.
388
389 'connect' <service>::
390 Connects to given service. Standard input and standard output
391 of helper are connected to specified service (git prefix is
392 included in service name so e.g. fetching uses 'git-upload-pack'
393 as service) on remote side. Valid replies to this command are
394 empty line (connection established), 'fallback' (no smart
395 transport support, fall back to dumb transports) and just
396 exiting with error message printed (can't connect, don't
397 bother trying to fall back). After line feed terminating the
398 positive (empty) response, the output of service starts. After
399 the connection ends, the remote helper exits.
400 +
401 Supported if the helper has the "connect" capability.
402
403 'stateless-connect' <service>::
404 Experimental; for internal use only.
405 Connects to the given remote service for communication using
406 git's wire-protocol version 2. Valid replies to this command
407 are empty line (connection established), 'fallback' (no smart
408 transport support, fall back to dumb transports) and just
409 exiting with error message printed (can't connect, don't bother
410 trying to fall back). After line feed terminating the positive
411 (empty) response, the output of the service starts. Messages
412 (both request and response) must consist of zero or more
413 PKT-LINEs, terminating in a flush packet. Response messages will
414 then have a response end packet after the flush packet to
415 indicate the end of a response. The client must not
416 expect the server to store any state in between request-response
417 pairs. After the connection ends, the remote helper exits.
418 +
419 Supported if the helper has the "stateless-connect" capability.
420
421 If a fatal error occurs, the program writes the error message to
422 stderr and exits. The caller should expect that a suitable error
423 message has been printed if the child closes the connection without
424 completing a valid response for the current command.
425
426 Additional commands may be supported, as may be determined from
427 capabilities reported by the helper.
428
429 REF LIST ATTRIBUTES
430 -------------------
431
432 The 'list' command produces a list of refs in which each ref
433 may be followed by a list of attributes. The following ref list
434 attributes are defined.
435
436 'unchanged'::
437 This ref is unchanged since the last import or fetch, although
438 the helper cannot necessarily determine what value that produced.
439
440 REF LIST KEYWORDS
441 -----------------
442
443 The 'list' command may produce a list of key-value pairs.
444 The following keys are defined.
445
446 'object-format'::
447 The refs are using the given hash algorithm. This keyword is only
448 used if the server and client both support the object-format
449 extension.
450
451
452 OPTIONS
453 -------
454
455 The following options are defined and (under suitable circumstances)
456 set by Git if the remote helper has the 'option' capability.
457
458 'option verbosity' <n>::
459 Changes the verbosity of messages displayed by the helper.
460 A value of 0 for <n> means that processes operate
461 quietly, and the helper produces only error output.
462 1 is the default level of verbosity, and higher values
463 of <n> correspond to the number of -v flags passed on the
464 command line.
465
466 'option progress' {'true'|'false'}::
467 Enables (or disables) progress messages displayed by the
468 transport helper during a command.
469
470 'option depth' <depth>::
471 Deepens the history of a shallow repository.
472
473 'option deepen-since <timestamp>::
474 Deepens the history of a shallow repository based on time.
475
476 'option deepen-not <ref>::
477 Deepens the history of a shallow repository excluding ref.
478 Multiple options add up.
479
480 'option deepen-relative {'true'|'false'}::
481 Deepens the history of a shallow repository relative to
482 current boundary. Only valid when used with "option depth".
483
484 'option followtags' {'true'|'false'}::
485 If enabled the helper should automatically fetch annotated
486 tag objects if the object the tag points at was transferred
487 during the fetch command. If the tag is not fetched by
488 the helper a second fetch command will usually be sent to
489 ask for the tag specifically. Some helpers may be able to
490 use this option to avoid a second network connection.
491
492 'option dry-run' {'true'|'false'}:
493 If true, pretend the operation completed successfully,
494 but don't actually change any repository data. For most
495 helpers this only applies to the 'push', if supported.
496
497 'option servpath <c-style-quoted-path>'::
498 Sets service path (--upload-pack, --receive-pack etc.) for
499 next connect. Remote helper may support this option, but
500 must not rely on this option being set before
501 connect request occurs.
502
503 'option check-connectivity' {'true'|'false'}::
504 Request the helper to check connectivity of a clone.
505
506 'option force' {'true'|'false'}::
507 Request the helper to perform a force update. Defaults to
508 'false'.
509
510 'option cloning' {'true'|'false'}::
511 Notify the helper this is a clone request (i.e. the current
512 repository is guaranteed empty).
513
514 'option update-shallow' {'true'|'false'}::
515 Allow to extend .git/shallow if the new refs require it.
516
517 'option pushcert' {'true'|'false'}::
518 GPG sign pushes.
519
520 'option push-option <string>::
521 Transmit <string> as a push option. As the push option
522 must not contain LF or NUL characters, the string is not encoded.
523
524 'option from-promisor' {'true'|'false'}::
525 Indicate that these objects are being fetched from a promisor.
526
527 'option no-dependents' {'true'|'false'}::
528 Indicate that only the objects wanted need to be fetched, not
529 their dependents.
530
531 'option atomic' {'true'|'false'}::
532 When pushing, request the remote server to update refs in a single atomic
533 transaction. If successful, all refs will be updated, or none will. If the
534 remote side does not support this capability, the push will fail.
535
536 'option object-format' {'true'|algorithm}::
537 If 'true', indicate that the caller wants hash algorithm information
538 to be passed back from the remote. This mode is used when fetching
539 refs.
540 +
541 If set to an algorithm, indicate that the caller wants to interact with
542 the remote side using that algorithm.
543
544 SEE ALSO
545 --------
546 linkgit:git-remote[1]
547
548 linkgit:git-remote-ext[1]
549
550 linkgit:git-remote-fd[1]
551
552 linkgit:git-fast-import[1]
553
554 GIT
555 ---
556 Part of the linkgit:git[1] suite