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1gitremote-helpers(7)
2====================
3
4NAME
5----
6gitremote-helpers - Helper programs to interact with remote repositories
7
8SYNOPSIS
9--------
10[verse]
11'git remote-<transport>' <repository> [<URL>]
12
13DESCRIPTION
14-----------
15
16Remote helper programs are normally not used directly by end users,
17but they are invoked by Git when it needs to interact with remote
18repositories Git does not support natively. A given helper will
19implement a subset of the capabilities documented here. When Git
20needs to interact with a repository using a remote helper, it spawns
21the helper as an independent process, sends commands to the helper's
22standard input, and expects results from the helper's standard
23output. Because a remote helper runs as an independent process from
24Git, there is no need to re-link Git to add a new helper, nor any
25need to link the helper with the implementation of Git.
26
27Every helper must support the "capabilities" command, which Git
28uses to determine what other commands the helper will accept. Those
29other commands can be used to discover and update remote refs,
30transport objects between the object database and the remote repository,
31and update the local object store.
32
33Git comes with a "curl" family of remote helpers, that handle various
34transport 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
38INVOCATION
39----------
40
41Remote helper programs are invoked with one or (optionally) two
42arguments. The first argument specifies a remote repository as in Git;
43it is either the name of a configured remote or a URL. The second
44argument specifies a URL; it is usually of the form
45'<transport>://<address>', but any arbitrary string is possible.
46The `GIT_DIR` environment variable is set up for the remote helper
47and can be used to determine where to store additional data or from
48which directory to invoke auxiliary Git commands.
49
50When Git encounters a URL of the form '<transport>://<address>', where
51'<transport>' is a protocol that it cannot handle natively, it
52automatically invokes 'git remote-<transport>' with the full URL as
53the second argument. If such a URL is encountered directly on the
54command line, the first argument is the same as the second, and if it
55is encountered in a configured remote, the first argument is the name
56of that remote.
57
58A URL of the form '<transport>::<address>' explicitly instructs Git to
59invoke 'git remote-<transport>' with '<address>' as the second
60argument. If such a URL is encountered directly on the command line,
61the first argument is '<address>', and if it is encountered in a
62configured remote, the first argument is the name of that remote.
63
64Additionally, 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
69INPUT FORMAT
70------------
71
72Git sends the remote helper a list of commands on standard input, one
73per line. The first command is always the 'capabilities' command, in
74response to which the remote helper must print a list of the
75capabilities it supports (see below) followed by a blank line. The
76response to the capabilities command determines what commands Git uses
77in the remainder of the command stream.
78
79The command stream is terminated by a blank line. In some cases
80(indicated in the documentation of the relevant commands), this blank
81line is followed by a payload in some other protocol (e.g., the pack
82protocol), while in others it indicates the end of input.
83
84Capabilities
85~~~~~~~~~~~~
86
87Each remote helper is expected to support only a subset of commands.
88The operations a helper supports are declared to Git in the response
89to the `capabilities` command (see COMMANDS, below).
90
91In the following, we list all defined capabilities and for
92each we list which commands a helper with that capability
93must provide.
94
95Capabilities 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+
103Supported 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+
111Supported 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+
117Supported 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+
123Supported commands: 'list for-push', 'export'.
124
125If a helper advertises 'connect', Git will use it if possible and
126fall back to another capability if the helper requests so when
127connecting (see the 'connect' command under COMMANDS).
128When choosing between 'push' and 'export', Git prefers 'push'.
129Other 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
137Capabilities 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+
145Supported 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+
153Supported commands: 'stateless-connect'.
154
155'fetch'::
156 Can discover remote refs and transfer objects reachable from
157 them to the local object store.
158+
159Supported 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+
165Supported 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'get'::
172 Can use the 'get' command to download a file from a given URI.
173
174If a helper advertises 'connect', Git will use it if possible and
175fall back to another capability if the helper requests so when
176connecting (see the 'connect' command under COMMANDS).
177When choosing between 'fetch' and 'import', Git prefers 'fetch'.
178Other frontends may have some other order of preference.
179
180Miscellaneous capabilities
181^^^^^^^^^^^^^^^^^^^^^^^^^^
182
183'option'::
184 For specifying settings like `verbosity` (how much output to
185 write to stderr) and `depth` (how much history is wanted in the
186 case of a shallow clone) that affect how other commands are
187 carried out.
188
189'refspec' <refspec>::
190 For remote helpers that implement 'import' or 'export', this capability
191 allows the refs to be constrained to a private namespace, instead of
192 writing to refs/heads or refs/remotes directly.
193 It is recommended that all importers providing the 'import'
194 capability use this. It's mandatory for 'export'.
195+
196A helper advertising the capability
197`refspec refs/heads/*:refs/svn/origin/branches/*`
198is saying that, when it is asked to `import refs/heads/topic`, the
199stream it outputs will update the `refs/svn/origin/branches/topic`
200ref.
201+
202This capability can be advertised multiple times. The first
203applicable refspec takes precedence. The left-hand of refspecs
204advertised with this capability must cover all refs reported by
205the list command. If no 'refspec' capability is advertised,
206there is an implied `refspec *:*`.
207+
208When writing remote-helpers for decentralized version control
209systems, it is advised to keep a local copy of the repository to
210interact with, and to let the private namespace refs point to this
211local repository, while the refs/remotes namespace is used to track
212the remote repository.
213
214'bidi-import'::
215 This modifies the 'import' capability.
216 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers
217 to retrieve information about blobs and trees that already exist in
218 fast-import's memory. This requires a channel from fast-import to the
219 remote-helper.
220 If it is advertised in addition to "import", Git establishes a pipe from
221 fast-import to the remote-helper's stdin.
222 It follows that Git and fast-import are both connected to the
223 remote-helper's stdin. Because Git can send multiple commands to
224 the remote-helper it is required that helpers that use 'bidi-import'
225 buffer all 'import' commands of a batch before sending data to fast-import.
226 This is to prevent mixing commands and fast-import responses on the
227 helper's stdin.
228
229'export-marks' <file>::
230 This modifies the 'export' capability, instructing Git to dump the
231 internal marks table to <file> when complete. For details,
232 read up on `--export-marks=<file>` in linkgit:git-fast-export[1].
233
234'import-marks' <file>::
235 This modifies the 'export' capability, instructing Git to load the
236 marks specified in <file> before processing any input. For details,
237 read up on `--import-marks=<file>` in linkgit:git-fast-export[1].
238
239'signed-tags'::
240 This modifies the 'export' capability, instructing Git to pass
241 `--signed-tags=verbatim` to linkgit:git-fast-export[1]. In the
242 absence of this capability, Git will use `--signed-tags=warn-strip`.
243
244'object-format'::
245 This indicates that the helper is able to interact with the remote
246 side using an explicit hash algorithm extension.
247
248
249COMMANDS
250--------
251
252Commands are given by the caller on the helper's standard input, one per line.
253
254'capabilities'::
255 Lists the capabilities of the helper, one per line, ending
256 with a blank line. Each capability may be preceded with '*',
257 which marks them mandatory for Git versions using the remote
258 helper to understand. Any unknown mandatory capability is a
259 fatal error.
260+
261Support for this command is mandatory.
262
263'list'::
264 Lists the refs, one per line, in the format "<value> <name>
265 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for
266 a symref, ":<keyword> <value>" for a key-value pair, or
267 "?" to indicate that the helper could not get the value of the
268 ref. A space-separated list of attributes follows the name;
269 unrecognized attributes are ignored. The list ends with a
270 blank line.
271+
272See REF LIST ATTRIBUTES for a list of currently defined attributes.
273See REF LIST KEYWORDS for a list of currently defined keywords.
274+
275Supported if the helper has the "fetch" or "import" capability.
276
277'list for-push'::
278 Similar to 'list', except that it is used if and only if
279 the caller wants to the resulting ref list to prepare
280 push commands.
281 A helper supporting both push and fetch can use this
282 to distinguish for which operation the output of 'list'
283 is going to be used, possibly reducing the amount
284 of work that needs to be performed.
285+
286Supported if the helper has the "push" or "export" capability.
287
288'option' <name> <value>::
289 Sets the transport helper option <name> to <value>. Outputs a
290 single line containing one of 'ok' (option successfully set),
291 'unsupported' (option not recognized) or 'error <msg>'
292 (option <name> is supported but <value> is not valid
293 for it). Options should be set before other commands,
294 and may influence the behavior of those commands.
295+
296See OPTIONS for a list of currently defined options.
297+
298Supported if the helper has the "option" capability.
299
300'fetch' <sha1> <name>::
301 Fetches the given object, writing the necessary objects
302 to the database. Fetch commands are sent in a batch, one
303 per line, terminated with a blank line.
304 Outputs a single blank line when all fetch commands in the
305 same batch are complete. Only objects which were reported
306 in the output of 'list' with a sha1 may be fetched this way.
307+
308Optionally may output a 'lock <file>' line indicating the full path of
309a file under `$GIT_DIR/objects/pack` which is keeping a pack until
310refs can be suitably updated. The path must end with `.keep`. This is
311a mechanism to name a <pack,idx,keep> tuple by giving only the keep
312component. The kept pack will not be deleted by a concurrent repack,
313even though its objects may not be referenced until the fetch completes.
314The `.keep` file will be deleted at the conclusion of the fetch.
315+
316If option 'check-connectivity' is requested, the helper must output
317'connectivity-ok' if the clone is self-contained and connected.
318+
319Supported if the helper has the "fetch" capability.
320
321'push' +<src>:<dst>::
322 Pushes the given local <src> commit or branch to the
323 remote branch described by <dst>. A batch sequence of
324 one or more 'push' commands is terminated with a blank line
325 (if there is only one reference to push, a single 'push' command
326 is followed by a blank line). For example, the following would
327 be two batches of 'push', the first asking the remote-helper
328 to push the local ref 'master' to the remote ref 'master' and
329 the local `HEAD` to the remote 'branch', and the second
330 asking to push ref 'foo' to ref 'bar' (forced update requested
331 by the '+').
332+
333------------
334push refs/heads/master:refs/heads/master
335push HEAD:refs/heads/branch
336\n
337push +refs/heads/foo:refs/heads/bar
338\n
339------------
340+
341Zero or more protocol options may be entered after the last 'push'
342command, before the batch's terminating blank line.
343+
344When the push is complete, outputs one or more 'ok <dst>' or
345'error <dst> <why>?' lines to indicate success or failure of
346each pushed ref. The status report output is terminated by
347a blank line. The option field <why> may be quoted in a C
348style string if it contains an LF.
349+
350Supported if the helper has the "push" capability.
351
352'import' <name>::
353 Produces a fast-import stream which imports the current value
354 of the named ref. It may additionally import other refs as
355 needed to construct the history efficiently. The script writes
356 to a helper-specific private namespace. The value of the named
357 ref should be written to a location in this namespace derived
358 by applying the refspecs from the "refspec" capability to the
359 name of the ref.
360+
361Especially useful for interoperability with a foreign versioning
362system.
363+
364Just like 'push', a batch sequence of one or more 'import' is
365terminated with a blank line. For each batch of 'import', the remote
366helper should produce a fast-import stream terminated by a 'done'
367command.
368+
369Note that if the 'bidi-import' capability is used the complete batch
370sequence has to be buffered before starting to send data to fast-import
371to prevent mixing of commands and fast-import responses on the helper's
372stdin.
373+
374Supported if the helper has the "import" capability.
375
376'export'::
377 Instructs the remote helper that any subsequent input is
378 part of a fast-import stream (generated by 'git fast-export')
379 containing objects which should be pushed to the remote.
380+
381Especially useful for interoperability with a foreign versioning
382system.
383+
384The 'export-marks' and 'import-marks' capabilities, if specified,
385affect this command in so far as they are passed on to 'git
386fast-export', which then will load/store a table of marks for
387local objects. This can be used to implement for incremental
388operations.
389+
390Supported if the helper has the "export" capability.
391
392'connect' <service>::
393 Connects to given service. Standard input and standard output
394 of helper are connected to specified service (git prefix is
395 included in service name so e.g. fetching uses 'git-upload-pack'
396 as service) on remote side. Valid replies to this command are
397 empty line (connection established), 'fallback' (no smart
398 transport support, fall back to dumb transports) and just
399 exiting with error message printed (can't connect, don't
400 bother trying to fall back). After line feed terminating the
401 positive (empty) response, the output of service starts. After
402 the connection ends, the remote helper exits.
403+
404Supported if the helper has the "connect" capability.
405
406'stateless-connect' <service>::
407 Experimental; for internal use only.
408 Connects to the given remote service for communication using
409 git's wire-protocol version 2. Valid replies to this command
410 are empty line (connection established), 'fallback' (no smart
411 transport support, fall back to dumb transports) and just
412 exiting with error message printed (can't connect, don't bother
413 trying to fall back). After line feed terminating the positive
414 (empty) response, the output of the service starts. Messages
415 (both request and response) must consist of zero or more
416 PKT-LINEs, terminating in a flush packet. Response messages will
417 then have a response end packet after the flush packet to
418 indicate the end of a response. The client must not
419 expect the server to store any state in between request-response
420 pairs. After the connection ends, the remote helper exits.
421+
422Supported if the helper has the "stateless-connect" capability.
423
424'get' <uri> <path>::
425 Downloads the file from the given `<uri>` to the given `<path>`. If
426 `<path>.temp` exists, then Git assumes that the `.temp` file is a
427 partial download from a previous attempt and will resume the
428 download from that position.
429
430If a fatal error occurs, the program writes the error message to
431stderr and exits. The caller should expect that a suitable error
432message has been printed if the child closes the connection without
433completing a valid response for the current command.
434
435Additional commands may be supported, as may be determined from
436capabilities reported by the helper.
437
438REF LIST ATTRIBUTES
439-------------------
440
441The 'list' command produces a list of refs in which each ref
442may be followed by a list of attributes. The following ref list
443attributes are defined.
444
445'unchanged'::
446 This ref is unchanged since the last import or fetch, although
447 the helper cannot necessarily determine what value that produced.
448
449REF LIST KEYWORDS
450-----------------
451
452The 'list' command may produce a list of key-value pairs.
453The following keys are defined.
454
455'object-format'::
456 The refs are using the given hash algorithm. This keyword is only
457 used if the server and client both support the object-format
458 extension.
459
460
461OPTIONS
462-------
463
464The following options are defined and (under suitable circumstances)
465set by Git if the remote helper has the 'option' capability.
466
467'option verbosity' <n>::
468 Changes the verbosity of messages displayed by the helper.
469 A value of 0 for <n> means that processes operate
470 quietly, and the helper produces only error output.
471 1 is the default level of verbosity, and higher values
472 of <n> correspond to the number of -v flags passed on the
473 command line.
474
475'option progress' {'true'|'false'}::
476 Enables (or disables) progress messages displayed by the
477 transport helper during a command.
478
479'option depth' <depth>::
480 Deepens the history of a shallow repository.
481
482'option deepen-since' <timestamp>::
483 Deepens the history of a shallow repository based on time.
484
485'option deepen-not' <ref>::
486 Deepens the history of a shallow repository excluding ref.
487 Multiple options add up.
488
489'option deepen-relative' {'true'|'false'}::
490 Deepens the history of a shallow repository relative to
491 current boundary. Only valid when used with "option depth".
492
493'option followtags' {'true'|'false'}::
494 If enabled the helper should automatically fetch annotated
495 tag objects if the object the tag points at was transferred
496 during the fetch command. If the tag is not fetched by
497 the helper a second fetch command will usually be sent to
498 ask for the tag specifically. Some helpers may be able to
499 use this option to avoid a second network connection.
500
501'option dry-run' {'true'|'false'}::
502 If true, pretend the operation completed successfully,
503 but don't actually change any repository data. For most
504 helpers this only applies to the 'push', if supported.
505
506'option servpath <c-style-quoted-path>'::
507 Sets service path (--upload-pack, --receive-pack etc.) for
508 next connect. Remote helper may support this option, but
509 must not rely on this option being set before
510 connect request occurs.
511
512'option check-connectivity' {'true'|'false'}::
513 Request the helper to check connectivity of a clone.
514
515'option force' {'true'|'false'}::
516 Request the helper to perform a force update. Defaults to
517 'false'.
518
519'option cloning' {'true'|'false'}::
520 Notify the helper this is a clone request (i.e. the current
521 repository is guaranteed empty).
522
523'option update-shallow' {'true'|'false'}::
524 Allow to extend .git/shallow if the new refs require it.
525
526'option pushcert' {'true'|'false'}::
527 GPG sign pushes.
528
529'option push-option' <string>::
530 Transmit <string> as a push option. As the push option
531 must not contain LF or NUL characters, the string is not encoded.
532
533'option from-promisor' {'true'|'false'}::
534 Indicate that these objects are being fetched from a promisor.
535
536'option no-dependents' {'true'|'false'}::
537 Indicate that only the objects wanted need to be fetched, not
538 their dependents.
539
540'option atomic' {'true'|'false'}::
541 When pushing, request the remote server to update refs in a single atomic
542 transaction. If successful, all refs will be updated, or none will. If the
543 remote side does not support this capability, the push will fail.
544
545'option object-format true'::
546 Indicate that the caller wants hash algorithm information
547 to be passed back from the remote. This mode is used when fetching
548 refs.
549
550SEE ALSO
551--------
552linkgit:git-remote[1]
553
554linkgit:git-remote-ext[1]
555
556linkgit:git-remote-fd[1]
557
558linkgit:git-fast-import[1]
559
560GIT
561---
562Part of the linkgit:git[1] suite