1GITREMOTE-HELPERS(7) Git Manual GITREMOTE-HELPERS(7)
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6 gitremote-helpers - Helper programs to interact with remote
7 repositories
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10 git remote-<transport> <repository> [<URL>]
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13 Remote helper programs are normally not used directly by end users, but
14 they are invoked by Git when it needs to interact with remote
15 repositories Git does not support natively. A given helper will
16 implement a subset of the capabilities documented here. When Git needs
17 to interact with a repository using a remote helper, it spawns the
18 helper as an independent process, sends commands to the helper’s
19 standard input, and expects results from the helper’s standard output.
20 Because a remote helper runs as an independent process from Git, there
21 is no need to re-link Git to add a new helper, nor any need to link the
22 helper with the implementation of Git.
23 Every helper must support the "capabilities" command, which Git uses to
25 determine what other commands the helper will accept. Those other
26 commands can be used to discover and update remote refs, transport
27 objects between the object database and the remote repository, and
28 update the local object store.
29 Git comes with a "curl" family of remote helpers, that handle various
31 transport protocols, such as git-remote-http, git-remote-https,
32 git-remote-ftp and git-remote-ftps. They implement the capabilities
33 fetch, option, and push.
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36 Remote helper programs are invoked with one or (optionally) two
37 arguments. The first argument specifies a remote repository as in Git;
38 it is either the name of a configured remote or a URL. The second
39 argument specifies a URL; it is usually of the form
40 <transport>://<address>, but any arbitrary string is possible. The
41 GIT_DIR environment variable is set up for the remote helper and can be
42 used to determine where to store additional data or from which
43 directory to invoke auxiliary Git commands.
44 When Git encounters a URL of the form <transport>://<address>, where
46 <transport> is a protocol that it cannot handle natively, it
47 automatically invokes git remote-<transport> with the full URL as the
48 second argument. If such a URL is encountered directly on the command
49 line, the first argument is the same as the second, and if it is
50 encountered in a configured remote, the first argument is the name of
51 that remote.
52 A URL of the form <transport>::<address> explicitly instructs Git to
54 invoke git remote-<transport> with <address> as the second argument. If
55 such a URL is encountered directly on the command line, the first
56 argument is <address>, and if it is encountered in a configured remote,
57 the first argument is the name of that remote.
58 Additionally, when a configured remote has remote.<name>.vcs set to
60 <transport>, Git explicitly invokes git remote-<transport> with <name>
61 as the first argument. If set, the second argument is
62 remote.<name>.url; otherwise, the second argument is omitted.
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65 Git sends the remote helper a list of commands on standard input, one
66 per line. The first command is always the capabilities command, in
67 response to which the remote helper must print a list of the
68 capabilities it supports (see below) followed by a blank line. The
69 response to the capabilities command determines what commands Git uses
70 in the remainder of the command stream.
71 The command stream is terminated by a blank line. In some cases
73 (indicated in the documentation of the relevant commands), this blank
74 line is followed by a payload in some other protocol (e.g., the pack
75 protocol), while in others it indicates the end of input.
76 Capabilities
78 Each remote helper is expected to support only a subset of commands.
79 The operations a helper supports are declared to Git in the response to
80 the capabilities command (see COMMANDS, below).
81 In the following, we list all defined capabilities and for each we list
83 which commands a helper with that capability must provide.
84 Capabilities for Pushing
86 connect
87 Can attempt to connect to git receive-pack (for pushing), git
88 upload-pack, etc for communication using git’s native packfile
89 protocol. This requires a bidirectional, full-duplex
90 connection.
91 Supported commands: connect.
93 stateless-connect
95 Experimental; for internal use only. Can attempt to connect to
96 a remote server for communication using git’s wire-protocol
97 version 2. See the documentation for the stateless-connect
98 command for more information.
99 Supported commands: stateless-connect.
101 push
103 Can discover remote refs and push local commits and the history
104 leading up to them to new or existing remote refs.
105 Supported commands: list for-push, push.
107 export
109 Can discover remote refs and push specified objects from a
110 fast-import stream to remote refs.
111 Supported commands: list for-push, export.
113 If a helper advertises connect, Git will use it if possible and
115 fall back to another capability if the helper requests so when
116 connecting (see the connect command under COMMANDS). When choosing
117 between push and export, Git prefers push. Other frontends may have
118 some other order of preference.
119 no-private-update
121 When using the refspec capability, git normally updates the
122 private ref on successful push. This update is disabled when
123 the remote-helper declares the capability no-private-update.
124 Capabilities for Fetching
126 connect
127 Can try to connect to git upload-pack (for fetching), git
128 receive-pack, etc for communication using the Git’s native
129 packfile protocol. This requires a bidirectional, full-duplex
130 connection.
131 Supported commands: connect.
133 stateless-connect
135 Experimental; for internal use only. Can attempt to connect to
136 a remote server for communication using git’s wire-protocol
137 version 2. See the documentation for the stateless-connect
138 command for more information.
139 Supported commands: stateless-connect.
141 fetch
143 Can discover remote refs and transfer objects reachable from
144 them to the local object store.
145 Supported commands: list, fetch.
147 import
149 Can discover remote refs and output objects reachable from them
150 as a stream in fast-import format.
151 Supported commands: list, import.
153 check-connectivity
155 Can guarantee that when a clone is requested, the received pack
156 is self contained and is connected.
157 If a helper advertises connect, Git will use it if possible and
159 fall back to another capability if the helper requests so when
160 connecting (see the connect command under COMMANDS). When choosing
161 between fetch and import, Git prefers fetch. Other frontends may
162 have some other order of preference.
163 Miscellaneous capabilities
165 option
166 For specifying settings like verbosity (how much output to
167 write to stderr) and depth (how much history is wanted in the
168 case of a shallow clone) that affect how other commands are
169 carried out.
170 refspec <refspec>
172 For remote helpers that implement import or export, this
173 capability allows the refs to be constrained to a private
174 namespace, instead of writing to refs/heads or refs/remotes
175 directly. It is recommended that all importers providing the
176 import capability use this. It’s mandatory for export.
177 A helper advertising the capability refspec
179 refs/heads/*:refs/svn/origin/branches/* is saying that, when it
180 is asked to import refs/heads/topic, the stream it outputs will
181 update the refs/svn/origin/branches/topic ref.
182 This capability can be advertised multiple times. The first
184 applicable refspec takes precedence. The left-hand of refspecs
185 advertised with this capability must cover all refs reported by
186 the list command. If no refspec capability is advertised, there
187 is an implied refspec *:*.
188 When writing remote-helpers for decentralized version control
190 systems, it is advised to keep a local copy of the repository
191 to interact with, and to let the private namespace refs point
192 to this local repository, while the refs/remotes namespace is
193 used to track the remote repository.
194 bidi-import
196 This modifies the import capability. The fast-import commands
197 cat-blob and ls can be used by remote-helpers to retrieve
198 information about blobs and trees that already exist in
199 fast-import’s memory. This requires a channel from fast-import
200 to the remote-helper. If it is advertised in addition to
201 "import", Git establishes a pipe from fast-import to the
202 remote-helper’s stdin. It follows that Git and fast-import are
203 both connected to the remote-helper’s stdin. Because Git can
204 send multiple commands to the remote-helper it is required that
205 helpers that use bidi-import buffer all import commands of a
206 batch before sending data to fast-import. This is to prevent
207 mixing commands and fast-import responses on the helper’s
208 stdin.
209 export-marks <file>
211 This modifies the export capability, instructing Git to dump
212 the internal marks table to <file> when complete. For details,
213 read up on --export-marks=<file> in git-fast-export(1).
214 import-marks <file>
216 This modifies the export capability, instructing Git to load
217 the marks specified in <file> before processing any input. For
218 details, read up on --import-marks=<file> in git-fast-
219 export(1).
220 signed-tags
222 This modifies the export capability, instructing Git to pass
223 --signed-tags=verbatim to git-fast-export(1). In the absence of
224 this capability, Git will use --signed-tags=warn-strip.
225 object-format
227 This indicates that the helper is able to interact with the
228 remote side using an explicit hash algorithm extension.
229
231 Commands are given by the caller on the helper’s standard input, one
232 per line.
233 capabilities
235 Lists the capabilities of the helper, one per line, ending with a
236 blank line. Each capability may be preceded with *, which marks
237 them mandatory for Git versions using the remote helper to
238 understand. Any unknown mandatory capability is a fatal error.
239 Support for this command is mandatory.
241 list
243 Lists the refs, one per line, in the format "<value> <name> [<attr>
244 ...]". The value may be a hex sha1 hash, "@<dest>" for a symref,
245 ":<keyword> <value>" for a key-value pair, or "?" to indicate that
246 the helper could not get the value of the ref. A space-separated
247 list of attributes follows the name; unrecognized attributes are
248 ignored. The list ends with a blank line.
249 See REF LIST ATTRIBUTES for a list of currently defined attributes.
251 See REF LIST KEYWORDS for a list of currently defined keywords.
252 Supported if the helper has the "fetch" or "import" capability.
254 list for-push
256 Similar to list, except that it is used if and only if the caller
257 wants to the resulting ref list to prepare push commands. A helper
258 supporting both push and fetch can use this to distinguish for
259 which operation the output of list is going to be used, possibly
260 reducing the amount of work that needs to be performed.
261 Supported if the helper has the "push" or "export" capability.
263 option <name> <value>
265 Sets the transport helper option <name> to <value>. Outputs a
266 single line containing one of ok (option successfully set),
267 unsupported (option not recognized) or error <msg> (option <name>
268 is supported but <value> is not valid for it). Options should be
269 set before other commands, and may influence the behavior of those
270 commands.
271 See OPTIONS for a list of currently defined options.
273 Supported if the helper has the "option" capability.
275 fetch <sha1> <name>
277 Fetches the given object, writing the necessary objects to the
278 database. Fetch commands are sent in a batch, one per line,
279 terminated with a blank line. Outputs a single blank line when all
280 fetch commands in the same batch are complete. Only objects which
281 were reported in the output of list with a sha1 may be fetched this
282 way.
283 Optionally may output a lock <file> line indicating the full path
285 of a file under $GIT_DIR/objects/pack which is keeping a pack until
286 refs can be suitably updated. The path must end with .keep. This is
287 a mechanism to name a <pack,idx,keep> tuple by giving only the keep
288 component. The kept pack will not be deleted by a concurrent
289 repack, even though its objects may not be referenced until the
290 fetch completes. The .keep file will be deleted at the conclusion
291 of the fetch.
292 If option check-connectivity is requested, the helper must output
294 connectivity-ok if the clone is self-contained and connected.
295 Supported if the helper has the "fetch" capability.
297 push +<src>:<dst>
299 Pushes the given local <src> commit or branch to the remote branch
300 described by <dst>. A batch sequence of one or more push commands
301 is terminated with a blank line (if there is only one reference to
302 push, a single push command is followed by a blank line). For
303 example, the following would be two batches of push, the first
304 asking the remote-helper to push the local ref master to the remote
305 ref master and the local HEAD to the remote branch, and the second
306 asking to push ref foo to ref bar (forced update requested by the
307 +).
308 push refs/heads/master:refs/heads/master
310 push HEAD:refs/heads/branch
311 \n
312 push +refs/heads/foo:refs/heads/bar
313 \n
314 Zero or more protocol options may be entered after the last push
316 command, before the batch’s terminating blank line.
317 When the push is complete, outputs one or more ok <dst> or error
319 <dst> <why>? lines to indicate success or failure of each pushed
320 ref. The status report output is terminated by a blank line. The
321 option field <why> may be quoted in a C style string if it contains
322 an LF.
323 Supported if the helper has the "push" capability.
325 import <name>
327 Produces a fast-import stream which imports the current value of
328 the named ref. It may additionally import other refs as needed to
329 construct the history efficiently. The script writes to a
330 helper-specific private namespace. The value of the named ref
331 should be written to a location in this namespace derived by
332 applying the refspecs from the "refspec" capability to the name of
333 the ref.
334 Especially useful for interoperability with a foreign versioning
336 system.
337 Just like push, a batch sequence of one or more import is
339 terminated with a blank line. For each batch of import, the remote
340 helper should produce a fast-import stream terminated by a done
341 command.
342 Note that if the bidi-import capability is used the complete batch
344 sequence has to be buffered before starting to send data to
345 fast-import to prevent mixing of commands and fast-import responses
346 on the helper’s stdin.
347 Supported if the helper has the "import" capability.
349 export
351 Instructs the remote helper that any subsequent input is part of a
352 fast-import stream (generated by git fast-export) containing
353 objects which should be pushed to the remote.
354 Especially useful for interoperability with a foreign versioning
356 system.
357 The export-marks and import-marks capabilities, if specified,
359 affect this command in so far as they are passed on to git
360 fast-export, which then will load/store a table of marks for local
361 objects. This can be used to implement for incremental operations.
362 Supported if the helper has the "export" capability.
364 connect <service>
366 Connects to given service. Standard input and standard output of
367 helper are connected to specified service (git prefix is included
368 in service name so e.g. fetching uses git-upload-pack as service)
369 on remote side. Valid replies to this command are empty line
370 (connection established), fallback (no smart transport support,
371 fall back to dumb transports) and just exiting with error message
372 printed (can’t connect, don’t bother trying to fall back). After
373 line feed terminating the positive (empty) response, the output of
374 service starts. After the connection ends, the remote helper exits.
375 Supported if the helper has the "connect" capability.
377 stateless-connect <service>
379 Experimental; for internal use only. Connects to the given remote
380 service for communication using git’s wire-protocol version 2.
381 Valid replies to this command are empty line (connection
382 established), fallback (no smart transport support, fall back to
383 dumb transports) and just exiting with error message printed (can’t
384 connect, don’t bother trying to fall back). After line feed
385 terminating the positive (empty) response, the output of the
386 service starts. Messages (both request and response) must consist
387 of zero or more PKT-LINEs, terminating in a flush packet. Response
388 messages will then have a response end packet after the flush
389 packet to indicate the end of a response. The client must not
390 expect the server to store any state in between request-response
391 pairs. After the connection ends, the remote helper exits.
392 Supported if the helper has the "stateless-connect" capability.
394 If a fatal error occurs, the program writes the error message to stderr
396 and exits. The caller should expect that a suitable error message has
397 been printed if the child closes the connection without completing a
398 valid response for the current command.
399 Additional commands may be supported, as may be determined from
401 capabilities reported by the helper.
402
404 The list command produces a list of refs in which each ref may be
405 followed by a list of attributes. The following ref list attributes are
406 defined.
407 unchanged
409 This ref is unchanged since the last import or fetch, although the
410 helper cannot necessarily determine what value that produced.
411
413 The list command may produce a list of key-value pairs. The following
414 keys are defined.
415 object-format
417 The refs are using the given hash algorithm. This keyword is only
418 used if the server and client both support the object-format
419 extension.
420
422 The following options are defined and (under suitable circumstances)
423 set by Git if the remote helper has the option capability.
424 option verbosity <n>
426 Changes the verbosity of messages displayed by the helper. A value
427 of 0 for <n> means that processes operate quietly, and the helper
428 produces only error output. 1 is the default level of verbosity,
429 and higher values of <n> correspond to the number of -v flags
430 passed on the command line.
431 option progress {true|false}
433 Enables (or disables) progress messages displayed by the transport
434 helper during a command.
435 option depth <depth>
437 Deepens the history of a shallow repository.
438 'option deepen-since <timestamp>
440 Deepens the history of a shallow repository based on time.
441 'option deepen-not <ref>
443 Deepens the history of a shallow repository excluding ref. Multiple
444 options add up.
445 option deepen-relative {'true|false}
447 Deepens the history of a shallow repository relative to current
448 boundary. Only valid when used with "option depth".
449 option followtags {true|false}
451 If enabled the helper should automatically fetch annotated tag
452 objects if the object the tag points at was transferred during the
453 fetch command. If the tag is not fetched by the helper a second
454 fetch command will usually be sent to ask for the tag specifically.
455 Some helpers may be able to use this option to avoid a second
456 network connection.
457 option dry-run {true|false}: If true, pretend the operation completed
459 successfully, but don’t actually change any repository data. For most
460 helpers this only applies to the push, if supported.
461 option servpath <c-style-quoted-path>
463 Sets service path (--upload-pack, --receive-pack etc.) for next
464 connect. Remote helper may support this option, but must not rely
465 on this option being set before connect request occurs.
466 option check-connectivity {true|false}
468 Request the helper to check connectivity of a clone.
469 option force {true|false}
471 Request the helper to perform a force update. Defaults to false.
472 option cloning {true|false}
474 Notify the helper this is a clone request (i.e. the current
475 repository is guaranteed empty).
476 option update-shallow {true|false}
478 Allow to extend .git/shallow if the new refs require it.
479 option pushcert {true|false}
481 GPG sign pushes.
482 'option push-option <string>
484 Transmit <string> as a push option. As the push option must not
485 contain LF or NUL characters, the string is not encoded.
486 option from-promisor {true|false}
488 Indicate that these objects are being fetched from a promisor.
489 option no-dependents {true|false}
491 Indicate that only the objects wanted need to be fetched, not their
492 dependents.
493 option atomic {true|false}
495 When pushing, request the remote server to update refs in a single
496 atomic transaction. If successful, all refs will be updated, or
497 none will. If the remote side does not support this capability, the
498 push will fail.
499 option object-format {true|algorithm}
501 If true, indicate that the caller wants hash algorithm information
502 to be passed back from the remote. This mode is used when fetching
503 refs.
504 If set to an algorithm, indicate that the caller wants to interact
506 with the remote side using that algorithm.
507
509 git-remote(1)
510 git-remote-ext(1)
512 git-remote-fd(1)
514 git-fast-import(1)
516
518 Part of the git(1) suite
519Git 2.31.1 2021-03-26 GITREMOTE-HELPERS(7)