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 171If a helper advertises 'connect', Git will use it if possible and 172fall back to another capability if the helper requests so when 173connecting (see the 'connect' command under COMMANDS). 174When choosing between 'fetch' and 'import', Git prefers 'fetch'. 175Other frontends may have some other order of preference. 176 177Miscellaneous 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+ 193A helper advertising the capability 194`refspec refs/heads/*:refs/svn/origin/branches/*` 195is saying that, when it is asked to `import refs/heads/topic`, the 196stream it outputs will update the `refs/svn/origin/branches/topic` 197ref. 198+ 199This capability can be advertised multiple times. The first 200applicable refspec takes precedence. The left-hand of refspecs 201advertised with this capability must cover all refs reported by 202the list command. If no 'refspec' capability is advertised, 203there is an implied `refspec *:*`. 204+ 205When writing remote-helpers for decentralized version control 206systems, it is advised to keep a local copy of the repository to 207interact with, and to let the private namespace refs point to this 208local repository, while the refs/remotes namespace is used to track 209the 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`. 240 241 242 243COMMANDS 244-------- 245 246Commands are given by the caller on the helper's standard input, one per line. 247 248'capabilities':: 249 Lists the capabilities of the helper, one per line, ending 250 with a blank line. Each capability may be preceded with '*', 251 which marks them mandatory for Git versions using the remote 252 helper to understand. Any unknown mandatory capability is a 253 fatal error. 254+ 255Support for this command is mandatory. 256 257'list':: 258 Lists the refs, one per line, in the format "<value> <name> 259 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for 260 a symref, or "?" to indicate that the helper could not get the 261 value of the ref. A space-separated list of attributes follows 262 the name; unrecognized attributes are ignored. The list ends 263 with a blank line. 264+ 265See REF LIST ATTRIBUTES for a list of currently defined attributes. 266+ 267Supported if the helper has the "fetch" or "import" capability. 268 269'list for-push':: 270 Similar to 'list', except that it is used if and only if 271 the caller wants to the resulting ref list to prepare 272 push commands. 273 A helper supporting both push and fetch can use this 274 to distinguish for which operation the output of 'list' 275 is going to be used, possibly reducing the amount 276 of work that needs to be performed. 277+ 278Supported if the helper has the "push" or "export" capability. 279 280'option' <name> <value>:: 281 Sets the transport helper option <name> to <value>. Outputs a 282 single line containing one of 'ok' (option successfully set), 283 'unsupported' (option not recognized) or 'error <msg>' 284 (option <name> is supported but <value> is not valid 285 for it). Options should be set before other commands, 286 and may influence the behavior of those commands. 287+ 288See OPTIONS for a list of currently defined options. 289+ 290Supported if the helper has the "option" capability. 291 292'fetch' <sha1> <name>:: 293 Fetches the given object, writing the necessary objects 294 to the database. Fetch commands are sent in a batch, one 295 per line, terminated with a blank line. 296 Outputs a single blank line when all fetch commands in the 297 same batch are complete. Only objects which were reported 298 in the output of 'list' with a sha1 may be fetched this way. 299+ 300Optionally may output a 'lock <file>' line indicating the full path of 301a file under `$GIT_DIR/objects/pack` which is keeping a pack until 302refs can be suitably updated. The path must end with `.keep`. This is 303a mechanism to name a <pack,idx,keep> tuple by giving only the keep 304component. The kept pack will not be deleted by a concurrent repack, 305even though its objects may not be referenced until the fetch completes. 306The `.keep` file will be deleted at the conclusion of the fetch. 307+ 308If option 'check-connectivity' is requested, the helper must output 309'connectivity-ok' if the clone is self-contained and connected. 310+ 311Supported if the helper has the "fetch" capability. 312 313'push' +<src>:<dst>:: 314 Pushes the given local <src> commit or branch to the 315 remote branch described by <dst>. A batch sequence of 316 one or more 'push' commands is terminated with a blank line 317 (if there is only one reference to push, a single 'push' command 318 is followed by a blank line). For example, the following would 319 be two batches of 'push', the first asking the remote-helper 320 to push the local ref 'master' to the remote ref 'master' and 321 the local `HEAD` to the remote 'branch', and the second 322 asking to push ref 'foo' to ref 'bar' (forced update requested 323 by the '+'). 324+ 325------------ 326push refs/heads/master:refs/heads/master 327push HEAD:refs/heads/branch 328\n 329push +refs/heads/foo:refs/heads/bar 330\n 331------------ 332+ 333Zero or more protocol options may be entered after the last 'push' 334command, before the batch's terminating blank line. 335+ 336When the push is complete, outputs one or more 'ok <dst>' or 337'error <dst> <why>?' lines to indicate success or failure of 338each pushed ref. The status report output is terminated by 339a blank line. The option field <why> may be quoted in a C 340style string if it contains an LF. 341+ 342Supported if the helper has the "push" capability. 343 344'import' <name>:: 345 Produces a fast-import stream which imports the current value 346 of the named ref. It may additionally import other refs as 347 needed to construct the history efficiently. The script writes 348 to a helper-specific private namespace. The value of the named 349 ref should be written to a location in this namespace derived 350 by applying the refspecs from the "refspec" capability to the 351 name of the ref. 352+ 353Especially useful for interoperability with a foreign versioning 354system. 355+ 356Just like 'push', a batch sequence of one or more 'import' is 357terminated with a blank line. For each batch of 'import', the remote 358helper should produce a fast-import stream terminated by a 'done' 359command. 360+ 361Note that if the 'bidi-import' capability is used the complete batch 362sequence has to be buffered before starting to send data to fast-import 363to prevent mixing of commands and fast-import responses on the helper's 364stdin. 365+ 366Supported if the helper has the "import" capability. 367 368'export':: 369 Instructs the remote helper that any subsequent input is 370 part of a fast-import stream (generated by 'git fast-export') 371 containing objects which should be pushed to the remote. 372+ 373Especially useful for interoperability with a foreign versioning 374system. 375+ 376The 'export-marks' and 'import-marks' capabilities, if specified, 377affect this command in so far as they are passed on to 'git 378fast-export', which then will load/store a table of marks for 379local objects. This can be used to implement for incremental 380operations. 381+ 382Supported if the helper has the "export" capability. 383 384'connect' <service>:: 385 Connects to given service. Standard input and standard output 386 of helper are connected to specified service (git prefix is 387 included in service name so e.g. fetching uses 'git-upload-pack' 388 as service) on remote side. Valid replies to this command are 389 empty line (connection established), 'fallback' (no smart 390 transport support, fall back to dumb transports) and just 391 exiting with error message printed (can't connect, don't 392 bother trying to fall back). After line feed terminating the 393 positive (empty) response, the output of service starts. After 394 the connection ends, the remote helper exits. 395+ 396Supported if the helper has the "connect" capability. 397 398'stateless-connect' <service>:: 399 Experimental; for internal use only. 400 Connects to the given remote service for communication using 401 git's wire-protocol version 2. Valid replies to this command 402 are empty line (connection established), 'fallback' (no smart 403 transport support, fall back to dumb transports) and just 404 exiting with error message printed (can't connect, don't bother 405 trying to fall back). After line feed terminating the positive 406 (empty) response, the output of the service starts. Messages 407 (both request and response) must consist of zero or more 408 PKT-LINEs, terminating in a flush packet. The client must not 409 expect the server to store any state in between request-response 410 pairs. After the connection ends, the remote helper exits. 411+ 412Supported if the helper has the "stateless-connect" capability. 413 414If a fatal error occurs, the program writes the error message to 415stderr and exits. The caller should expect that a suitable error 416message has been printed if the child closes the connection without 417completing a valid response for the current command. 418 419Additional commands may be supported, as may be determined from 420capabilities reported by the helper. 421 422REF LIST ATTRIBUTES 423------------------- 424 425The 'list' command produces a list of refs in which each ref 426may be followed by a list of attributes. The following ref list 427attributes are defined. 428 429'unchanged':: 430 This ref is unchanged since the last import or fetch, although 431 the helper cannot necessarily determine what value that produced. 432 433OPTIONS 434------- 435 436The following options are defined and (under suitable circumstances) 437set by Git if the remote helper has the 'option' capability. 438 439'option verbosity' <n>:: 440 Changes the verbosity of messages displayed by the helper. 441 A value of 0 for <n> means that processes operate 442 quietly, and the helper produces only error output. 443 1 is the default level of verbosity, and higher values 444 of <n> correspond to the number of -v flags passed on the 445 command line. 446 447'option progress' {'true'|'false'}:: 448 Enables (or disables) progress messages displayed by the 449 transport helper during a command. 450 451'option depth' <depth>:: 452 Deepens the history of a shallow repository. 453 454'option deepen-since <timestamp>:: 455 Deepens the history of a shallow repository based on time. 456 457'option deepen-not <ref>:: 458 Deepens the history of a shallow repository excluding ref. 459 Multiple options add up. 460 461'option deepen-relative {'true'|'false'}:: 462 Deepens the history of a shallow repository relative to 463 current boundary. Only valid when used with "option depth". 464 465'option followtags' {'true'|'false'}:: 466 If enabled the helper should automatically fetch annotated 467 tag objects if the object the tag points at was transferred 468 during the fetch command. If the tag is not fetched by 469 the helper a second fetch command will usually be sent to 470 ask for the tag specifically. Some helpers may be able to 471 use this option to avoid a second network connection. 472 473'option dry-run' {'true'|'false'}: 474 If true, pretend the operation completed successfully, 475 but don't actually change any repository data. For most 476 helpers this only applies to the 'push', if supported. 477 478'option servpath <c-style-quoted-path>':: 479 Sets service path (--upload-pack, --receive-pack etc.) for 480 next connect. Remote helper may support this option, but 481 must not rely on this option being set before 482 connect request occurs. 483 484'option check-connectivity' {'true'|'false'}:: 485 Request the helper to check connectivity of a clone. 486 487'option force' {'true'|'false'}:: 488 Request the helper to perform a force update. Defaults to 489 'false'. 490 491'option cloning' {'true'|'false'}:: 492 Notify the helper this is a clone request (i.e. the current 493 repository is guaranteed empty). 494 495'option update-shallow' {'true'|'false'}:: 496 Allow to extend .git/shallow if the new refs require it. 497 498'option pushcert' {'true'|'false'}:: 499 GPG sign pushes. 500 501'option push-option <string>:: 502 Transmit <string> as a push option. As the push option 503 must not contain LF or NUL characters, the string is not encoded. 504 505'option from-promisor' {'true'|'false'}:: 506 Indicate that these objects are being fetched from a promisor. 507 508'option no-dependents' {'true'|'false'}:: 509 Indicate that only the objects wanted need to be fetched, not 510 their dependents. 511 512SEE ALSO 513-------- 514linkgit:git-remote[1] 515 516linkgit:git-remote-ext[1] 517 518linkgit:git-remote-fd[1] 519 520linkgit:git-fast-import[1] 521 522GIT 523--- 524Part of the linkgit:git[1] suite