1GITREMOTE-HELPERS(7)              Git Manual              GITREMOTE-HELPERS(7)
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NAME

6       gitremote-helpers - Helper programs to interact with remote
7       repositories
8

SYNOPSIS

10       git remote-<transport> <repository> [<URL>]
11

DESCRIPTION

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
24       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
30       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.
34

INVOCATION

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
45       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
53       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
59       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.
63

INPUT FORMAT

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
72       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
77   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
82       In the following, we list all defined capabilities and for each we list
83       which commands a helper with that capability must provide.
84
85       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
92               Supported commands: connect.
93
94           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
100               Supported commands: stateless-connect.
101
102           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
106               Supported commands: list for-push, push.
107
108           export
109               Can discover remote refs and push specified objects from a
110               fast-import stream to remote refs.
111
112               Supported commands: list for-push, export.
113
114           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
120           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
125       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
132               Supported commands: connect.
133
134           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
140               Supported commands: stateless-connect.
141
142           fetch
143               Can discover remote refs and transfer objects reachable from
144               them to the local object store.
145
146               Supported commands: list, fetch.
147
148           import
149               Can discover remote refs and output objects reachable from them
150               as a stream in fast-import format.
151
152               Supported commands: list, import.
153
154           check-connectivity
155               Can guarantee that when a clone is requested, the received pack
156               is self contained and is connected.
157
158           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
164       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
171           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
178               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
183               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
189               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
195           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
210           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
215           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
221           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
226           object-format
227               This indicates that the helper is able to interact with the
228               remote side using an explicit hash algorithm extension.
229

COMMANDS

231       Commands are given by the caller on the helper’s standard input, one
232       per line.
233
234       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
240           Support for this command is mandatory.
241
242       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
250           See REF LIST ATTRIBUTES for a list of currently defined attributes.
251           See REF LIST KEYWORDS for a list of currently defined keywords.
252
253           Supported if the helper has the "fetch" or "import" capability.
254
255       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
262           Supported if the helper has the "push" or "export" capability.
263
264       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
272           See OPTIONS for a list of currently defined options.
273
274           Supported if the helper has the "option" capability.
275
276       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
284           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
293           If option check-connectivity is requested, the helper must output
294           connectivity-ok if the clone is self-contained and connected.
295
296           Supported if the helper has the "fetch" capability.
297
298       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
309               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
315           Zero or more protocol options may be entered after the last push
316           command, before the batch’s terminating blank line.
317
318           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
324           Supported if the helper has the "push" capability.
325
326       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
335           Especially useful for interoperability with a foreign versioning
336           system.
337
338           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
343           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
348           Supported if the helper has the "import" capability.
349
350       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
355           Especially useful for interoperability with a foreign versioning
356           system.
357
358           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
363           Supported if the helper has the "export" capability.
364
365       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
376           Supported if the helper has the "connect" capability.
377
378       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
393           Supported if the helper has the "stateless-connect" capability.
394
395       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
400       Additional commands may be supported, as may be determined from
401       capabilities reported by the helper.
402

REF LIST ATTRIBUTES

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
408       unchanged
409           This ref is unchanged since the last import or fetch, although the
410           helper cannot necessarily determine what value that produced.
411

REF LIST KEYWORDS

413       The list command may produce a list of key-value pairs. The following
414       keys are defined.
415
416       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

OPTIONS

422       The following options are defined and (under suitable circumstances)
423       set by Git if the remote helper has the option capability.
424
425       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
432       option progress {true|false}
433           Enables (or disables) progress messages displayed by the transport
434           helper during a command.
435
436       option depth <depth>
437           Deepens the history of a shallow repository.
438
439       'option deepen-since <timestamp>
440           Deepens the history of a shallow repository based on time.
441
442       'option deepen-not <ref>
443           Deepens the history of a shallow repository excluding ref. Multiple
444           options add up.
445
446       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
450       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
458       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
462       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
467       option check-connectivity {true|false}
468           Request the helper to check connectivity of a clone.
469
470       option force {true|false}
471           Request the helper to perform a force update. Defaults to false.
472
473       option cloning {true|false}
474           Notify the helper this is a clone request (i.e. the current
475           repository is guaranteed empty).
476
477       option update-shallow {true|false}
478           Allow to extend .git/shallow if the new refs require it.
479
480       option pushcert {true|false}
481           GPG sign pushes.
482
483       '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
487       option from-promisor {true|false}
488           Indicate that these objects are being fetched from a promisor.
489
490       option no-dependents {true|false}
491           Indicate that only the objects wanted need to be fetched, not their
492           dependents.
493
494       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
500       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
505           If set to an algorithm, indicate that the caller wants to interact
506           with the remote side using that algorithm.
507

SEE ALSO

509       git-remote(1)
510
511       git-remote-ext(1)
512
513       git-remote-fd(1)
514
515       git-fast-import(1)
516

GIT

518       Part of the git(1) suite
519
520
521
522Git 2.31.1                        2021-03-26              GITREMOTE-HELPERS(7)
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