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NAME | SYNOPSIS | DESCRIPTION | PACKET-LINE FRAMING | INITIAL CLIENT REQUEST | CAPABILITY ADVERTISEMENT | COMMAND REQUEST | CAPABILITIES | GIT | NOTES | COLOPHON |
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GITPROTOCOL-V2(5) Git Manual GITPROTOCOL-V2(5)
gitprotocol-v2 - Git Wire Protocol, Version 2
<over-the-wire-protocol>
This document presents a specification for a version 2 of Git’s
wire protocol. Protocol v2 will improve upon v1 in the following
ways:
• Instead of multiple service names, multiple commands will be
supported by a single service
• Easily extendable as capabilities are moved into their own
section of the protocol, no longer being hidden behind a NUL
byte and limited by the size of a pkt-line
• Separate out other information hidden behind NUL bytes (e.g.
agent string as a capability and symrefs can be requested
using ls-refs)
• Reference advertisement will be omitted unless explicitly
requested
• ls-refs command to explicitly request some refs
• Designed with http and stateless-rpc in mind. With clear flush
semantics the http remote helper can simply act as a proxy
In protocol v2 communication is command oriented. When first
contacting a server a list of capabilities will be advertised.
Some of these capabilities will be commands which a client can
request be executed. Once a command has completed, a client can
reuse the connection and request that other commands be executed.
All communication is done using packet-line framing, just as in
v1. See gitprotocol-pack(5) and gitprotocol-common(5) for more
information.
In protocol v2 these special packets will have the following
semantics:
• 0000 Flush Packet (flush-pkt) - indicates the end of a message
• 0001 Delimiter Packet (delim-pkt) - separates sections of a
message
• 0002 Response End Packet (response-end-pkt) - indicates the
end of a response for stateless connections
In general a client can request to speak protocol v2 by sending
version=2 through the respective side-channel for the transport
being used which inevitably sets GIT_PROTOCOL. More information
can be found in gitprotocol-pack(5) and gitprotocol-http(5), as
well as the GIT_PROTOCOL definition in git(1). In all cases the
response from the server is the capability advertisement.
Git Transport
When using the git:// transport, you can request to use protocol
v2 by sending "version=2" as an extra parameter:
003egit-upload-pack /project.git\0host=myserver.com\0\0version=2\0
SSH and File Transport
When using either the ssh:// or file:// transport, the
GIT_PROTOCOL environment variable must be set explicitly to
include "version=2". The server may need to be configured to allow
this environment variable to pass.
HTTP Transport
When using the http:// or https:// transport a client makes a
"smart" info/refs request as described in gitprotocol-http(5) and
requests that v2 be used by supplying "version=2" in the
Git-Protocol header.
C: GET $GIT_URL/info/refs?service=git-upload-pack HTTP/1.0
C: Git-Protocol: version=2
A v2 server would reply:
S: 200 OK
S: <Some headers>
S: ...
S:
S: 000eversion 2\n
S: <capability-advertisement>
Subsequent requests are then made directly to the service
$GIT_URL/git-upload-pack. (This works the same for
git-receive-pack).
Uses the --http-backend-info-refs option to git-upload-pack(1).
The server may need to be configured to pass this header’s
contents via the GIT_PROTOCOL variable. See the discussion in
git-http-backend(1).
A server which decides to communicate (based on a request from a
client) using protocol version 2, notifies the client by sending a
version string in its initial response followed by an
advertisement of its capabilities. Each capability is a key with
an optional value. Clients must ignore all unknown keys. Semantics
of unknown values are left to the definition of each key. Some
capabilities will describe commands which can be requested to be
executed by the client.
capability-advertisement = protocol-version
capability-list
flush-pkt
protocol-version = PKT-LINE("version 2" LF)
capability-list = *capability
capability = PKT-LINE(key[=value] LF)
key = 1*(ALPHA | DIGIT | "-_")
value = 1*(ALPHA | DIGIT | " -_.,?\/{}[]()<>!@#$%^&*+=:;")
After receiving the capability advertisement, a client can then
issue a request to select the command it wants with any particular
capabilities or arguments. There is then an optional section where
the client can provide any command specific parameters or queries.
Only a single command can be requested at a time.
request = empty-request | command-request
empty-request = flush-pkt
command-request = command
capability-list
delim-pkt
command-args
flush-pkt
command = PKT-LINE("command=" key LF)
command-args = *command-specific-arg
command-specific-args are packet line framed arguments defined by
each individual command.
The server will then check to ensure that the client’s request is
comprised of a valid command as well as valid capabilities which
were advertised. If the request is valid the server will then
execute the command. A server MUST wait till it has received the
client’s entire request before issuing a response. The format of
the response is determined by the command being executed, but in
all cases a flush-pkt indicates the end of the response.
When a command has finished, and the client has received the
entire response from the server, a client can either request that
another command be executed or can terminate the connection. A
client may optionally send an empty request consisting of just a
flush-pkt to indicate that no more requests will be made.
There are two different types of capabilities: normal
capabilities, which can be used to convey information or alter the
behavior of a request, and commands, which are the core actions
that a client wants to perform (fetch, push, etc).
Protocol version 2 is stateless by default. This means that all
commands must only last a single round and be stateless from the
perspective of the server side, unless the client has requested a
capability indicating that state should be maintained by the
server. Clients MUST NOT require state management on the server
side in order to function correctly. This permits simple
round-robin load-balancing on the server side, without needing to
worry about state management.
agent
The server can advertise the agent capability with a value X (in
the form agent=X) to notify the client that the server is running
version X. The client may optionally send its own agent string by
including the agent capability with a value Y (in the form
agent=Y) in its request to the server (but it MUST NOT do so if
the server did not advertise the agent capability). The X and Y
strings may contain any printable ASCII characters except space
(i.e., the byte range 33 ⟨ x ⟨ 126), and are typically of the form
"package/version-os" (e.g., "git/1.8.3.1-Linux") where os is the
operating system name (e.g., "Linux"). X and Y can be configured
using the GIT_USER_AGENT environment variable and it takes
priority. The os is retrieved using the sysname field of the
uname(2) system call or its equivalent. The agent strings are
purely informative for statistics and debugging purposes, and MUST
NOT be used to programmatically assume the presence or absence of
particular features.
ls-refs
ls-refs is the command used to request a reference advertisement
in v2. Unlike the current reference advertisement, ls-refs takes
in arguments which can be used to limit the refs sent from the
server.
Additional features not supported in the base command will be
advertised as the value of the command in the capability
advertisement in the form of a space separated list of features:
"<command>=<feature-1> <feature-2>"
ls-refs takes in the following arguments:
symrefs
In addition to the object pointed by it, show the underlying ref
pointed by it when showing a symbolic ref.
peel
Show peeled tags.
ref-prefix <prefix>
When specified, only references having a prefix matching one of
the provided prefixes are displayed. Multiple instances may be
given, in which case references matching any prefix will be
shown. Note that this is purely for optimization; a server MAY
show refs not matching the prefix if it chooses, and clients
should filter the result themselves.
If the unborn feature is advertised the following argument can be
included in the client’s request.
unborn
The server will send information about HEAD even if it is a symref
pointing to an unborn branch in the form "unborn HEAD
symref-target:<target>".
The output of ls-refs is as follows:
output = *ref
flush-pkt
obj-id-or-unborn = (obj-id | "unborn")
ref = PKT-LINE(obj-id-or-unborn SP refname *(SP ref-attribute) LF)
ref-attribute = (symref | peeled)
symref = "symref-target:" symref-target
peeled = "peeled:" obj-id
fetch
fetch is the command used to fetch a packfile in v2. It can be
looked at as a modified version of the v1 fetch where the
ref-advertisement is stripped out (since the ls-refs command fills
that role) and the message format is tweaked to eliminate
redundancies and permit easy addition of future extensions.
Additional features not supported in the base command will be
advertised as the value of the command in the capability
advertisement in the form of a space separated list of features:
"<command>=<feature-1> <feature-2>"
A fetch request can take the following arguments:
want <oid>
Indicates to the server an object which the client wants to
retrieve. Wants can be anything and are not limited to
advertised objects.
have <oid>
Indicates to the server an object which the client has locally.
This allows the server to make a packfile which only contains
the objects that the client needs. Multiple 'have' lines can be
supplied.
done
Indicates to the server that negotiation should terminate (or
not even begin if performing a clone) and that the server should
use the information supplied in the request to construct the
packfile.
thin-pack
Request that a thin pack be sent, which is a pack with deltas
which reference base objects not contained within the pack (but
are known to exist at the receiving end). This can reduce the
network traffic significantly, but it requires the receiving end
to know how to "thicken" these packs by adding the missing bases
to the pack.
no-progress
Request that progress information that would normally be sent on
side-band channel 2, during the packfile transfer, should not be
sent. However, the side-band channel 3 is still used for error
responses.
include-tag
Request that annotated tags should be sent if the objects they
point to are being sent.
ofs-delta
Indicate that the client understands PACKv2 with delta referring
to its base by position in pack rather than by an oid. That is,
they can read OBJ_OFS_DELTA (aka type 6) in a packfile.
If the shallow feature is advertised the following arguments can
be included in the clients request as well as the potential
addition of the shallow-info section in the server’s response as
explained below.
shallow <oid>
A client must notify the server of all commits for which it only
has shallow copies (meaning that it doesn't have the parents of
a commit) by supplying a 'shallow <oid>' line for each such
object so that the server is aware of the limitations of the
client's history. This is so that the server is aware that the
client may not have all objects reachable from such commits.
deepen <depth>
Requests that the fetch/clone should be shallow having a commit
depth of <depth> relative to the remote side.
deepen-relative
Requests that the semantics of the "deepen" command be changed
to indicate that the depth requested is relative to the client's
current shallow boundary, instead of relative to the requested
commits.
deepen-since <timestamp>
Requests that the shallow clone/fetch should be cut at a
specific time, instead of depth. Internally it's equivalent to
doing "git rev-list --max-age=<timestamp>". Cannot be used with
"deepen".
deepen-not <rev>
Requests that the shallow clone/fetch should be cut at a
specific revision specified by '<rev>', instead of a depth.
Internally it's equivalent of doing "git rev-list --not <rev>".
Cannot be used with "deepen", but can be used with
"deepen-since".
If the filter feature is advertised, the following argument can be
included in the client’s request:
filter <filter-spec>
Request that various objects from the packfile be omitted
using one of several filtering techniques. These are intended
for use with partial clone and partial fetch operations. See
`rev-list` for possible "filter-spec" values. When communicating
with other processes, senders SHOULD translate scaled integers
(e.g. "1k") into a fully-expanded form (e.g. "1024") to aid
interoperability with older receivers that may not understand
newly-invented scaling suffixes. However, receivers SHOULD
accept the following suffixes: 'k', 'm', and 'g' for 1024,
1048576, and 1073741824, respectively.
If the ref-in-want feature is advertised, the following argument
can be included in the client’s request as well as the potential
addition of the wanted-refs section in the server’s response as
explained below.
want-ref <ref>
Indicates to the server that the client wants to retrieve a
particular ref, where <ref> is the full name of a ref on the
server. It is a protocol error to send want-ref for the
same ref more than once.
If the sideband-all feature is advertised, the following argument
can be included in the client’s request:
sideband-all
Instruct the server to send the whole response multiplexed, not just
the packfile section. All non-flush and non-delim PKT-LINE in the
response (not only in the packfile section) will then start with a byte
indicating its sideband (1, 2, or 3), and the server may send "0005\2"
(a PKT-LINE of sideband 2 with no payload) as a keepalive packet.
If the packfile-uris feature is advertised, the following argument
can be included in the client’s request as well as the potential
addition of the packfile-uris section in the server’s response as
explained below. Note that at most one packfile-uris line can be
sent to the server.
packfile-uris <comma-separated-list-of-protocols>
Indicates to the server that the client is willing to receive
URIs of any of the given protocols in place of objects in the
sent packfile. Before performing the connectivity check, the
client should download from all given URIs. Currently, the
protocols supported are "http" and "https".
If the wait-for-done feature is advertised, the following argument
can be included in the client’s request.
wait-for-done
Indicates to the server that it should never send "ready", but
should wait for the client to say "done" before sending the
packfile.
The response of fetch is broken into a number of sections
separated by delimiter packets (0001), with each section beginning
with its section header. Most sections are sent only when the
packfile is sent.
output = acknowledgements flush-pkt |
[acknowledgments delim-pkt] [shallow-info delim-pkt]
[wanted-refs delim-pkt] [packfile-uris delim-pkt]
packfile flush-pkt
acknowledgments = PKT-LINE("acknowledgments" LF)
(nak | *ack)
(ready)
ready = PKT-LINE("ready" LF)
nak = PKT-LINE("NAK" LF)
ack = PKT-LINE("ACK" SP obj-id LF)
shallow-info = PKT-LINE("shallow-info" LF)
*PKT-LINE((shallow | unshallow) LF)
shallow = "shallow" SP obj-id
unshallow = "unshallow" SP obj-id
wanted-refs = PKT-LINE("wanted-refs" LF)
*PKT-LINE(wanted-ref LF)
wanted-ref = obj-id SP refname
packfile-uris = PKT-LINE("packfile-uris" LF) *packfile-uri
packfile-uri = PKT-LINE(40*(HEXDIGIT) SP *%x20-ff LF)
packfile = PKT-LINE("packfile" LF)
*PKT-LINE(%x01-03 *%x00-ff)
acknowledgments section
* If the client determines that it is finished with negotiations by
sending a "done" line (thus requiring the server to send a packfile),
the acknowledgments sections MUST be omitted from the server's
response.
• Always begins with the section header "acknowledgments"
• The server will respond with "NAK" if none of the object ids
sent as have lines were common.
• The server will respond with "ACK obj-id" for all of the
object ids sent as have lines which are common.
• A response cannot have both "ACK" lines as well as a "NAK"
line.
• The server will respond with a "ready" line indicating that
the server has found an acceptable common base and is ready to
make and send a packfile (which will be found in the packfile
section of the same response)
• If the server has found a suitable cut point and has decided
to send a "ready" line, then the server can decide to (as an
optimization) omit any "ACK" lines it would have sent during
its response. This is because the server will have already
determined the objects it plans to send to the client and no
further negotiation is needed.
shallow-info section
* If the client has requested a shallow fetch/clone, a shallow
client requests a fetch or the server is shallow then the
server's response may include a shallow-info section. The
shallow-info section will be included if (due to one of the
above conditions) the server needs to inform the client of any
shallow boundaries or adjustments to the clients already
existing shallow boundaries.
• Always begins with the section header "shallow-info"
• If a positive depth is requested, the server will compute the
set of commits which are no deeper than the desired depth.
• The server sends a "shallow obj-id" line for each commit whose
parents will not be sent in the following packfile.
• The server sends an "unshallow obj-id" line for each commit
which the client has indicated is shallow, but is no longer
shallow as a result of the fetch (due to its parents being
sent in the following packfile).
• The server MUST NOT send any "unshallow" lines for anything
which the client has not indicated was shallow as a part of
its request.
wanted-refs section
* This section is only included if the client has requested a
ref using a 'want-ref' line and if a packfile section is also
included in the response.
• Always begins with the section header "wanted-refs".
• The server will send a ref listing ("<oid> <refname>") for
each reference requested using want-ref lines.
• The server MUST NOT send any refs which were not requested
using want-ref lines.
packfile-uris section
* This section is only included if the client sent
'packfile-uris' and the server has at least one such URI to
send.
• Always begins with the section header "packfile-uris".
• For each URI the server sends, it sends a hash of the pack’s
contents (as output by git index-pack) followed by the URI.
• The hashes are 40 hex characters long. When Git upgrades to a
new hash algorithm, this might need to be updated. (It should
match whatever index-pack outputs after "pack\t" or "keep\t".
packfile section
* This section is only included if the client has sent 'want'
lines in its request and either requested that no more
negotiation be done by sending 'done' or if the server has
decided it has found a sufficient cut point to produce a
packfile.
• Always begins with the section header "packfile"
• The transmission of the packfile begins immediately after the
section header
• The data transfer of the packfile is always multiplexed, using
the same semantics of the side-band-64k capability from
protocol version 1. This means that each packet, during the
packfile data stream, is made up of a leading 4-byte pkt-line
length (typical of the pkt-line format), followed by a 1-byte
stream code, followed by the actual data.
The stream code can be one of:
1 - pack data
2 - progress messages
3 - fatal error message just before stream aborts
server-option
If advertised, indicates that any number of server specific
options can be included in a request. This is done by sending each
option as a "server-option=<option>" capability line in the
capability-list section of a request.
The provided options must not contain a NUL or LF character.
object-format
The server can advertise the object-format capability with a value
X (in the form object-format=X) to notify the client that the
server is able to deal with objects using hash algorithm X. If not
specified, the server is assumed to only handle SHA-1. If the
client would like to use a hash algorithm other than SHA-1, it
should specify its object-format string.
session-id=<session-id>
The server may advertise a session ID that can be used to identify
this process across multiple requests. The client may advertise
its own session ID back to the server as well.
Session IDs should be unique to a given process. They must fit
within a packet-line, and must not contain non-printable or
whitespace characters. The current implementation uses trace2
session IDs (see api-trace2[1] for details), but this may change
and users of the session ID should not rely on this fact.
object-info
object-info is the command to retrieve information about one or
more objects. Its main purpose is to allow a client to make
decisions based on this information without having to fully fetch
objects. Object size is the only information that is currently
supported.
An object-info request takes the following arguments:
size
Requests size information to be returned for each listed object id.
oid <oid>
Indicates to the server an object which the client wants to obtain
information for.
The response of object-info is a list of the requested object ids
and associated requested information, each separated by a single
space.
output = info flush-pkt
info = PKT-LINE(attrs) LF)
*PKT-LINE(obj-info LF)
attrs = attr | attrs SP attrs
attr = "size"
obj-info = obj-id SP obj-size
bundle-uri
If the bundle-uri capability is advertised, the server supports
the ‘bundle-uri’ command.
The capability is currently advertised with no value (i.e. not
"bundle-uri=somevalue"), a value may be added in the future for
supporting command-wide extensions. Clients MUST ignore any
unknown capability values and proceed with the 'bundle-uri` dialog
they support.
The bundle-uri command is intended to be issued before fetch to
get URIs to bundle files (see git-bundle(1)) to "seed" and inform
the subsequent fetch command.
The client CAN issue bundle-uri before or after any other valid
command. To be useful to clients it’s expected that it’ll be
issued after an ls-refs and before fetch, but CAN be issued at any
time in the dialog.
DISCUSSION of bundle-uri
The intent of the feature is optimize for server resource
consumption in the common case by changing the common case of
fetching a very large PACK during git-clone(1) into a smaller
incremental fetch.
It also allows servers to achieve better caching in
combination with an uploadpack.packObjectsHook (see
git-config(1)).
By having new clones or fetches be a more predictable and
common negotiation against the tips of recently produces
*.bundle file(s). Servers might even pre-generate the results
of such negotiations for the uploadpack.packObjectsHook as new
pushes come in.
One way that servers could take advantage of these bundles is
that the server would anticipate that fresh clones will
download a known bundle, followed by catching up to the
current state of the repository using ref tips found in that
bundle (or bundles).
PROTOCOL for bundle-uri
A bundle-uri request takes no arguments, and as noted above
does not currently advertise a capability value. Both may be
added in the future.
When the client issues a command=bundle-uri request, the
response is a list of key-value pairs provided as packet lines
with value <key>=<value>. Each <key> should be interpreted as
a config key from the bundle.* namespace to construct a list
of bundles. These keys are grouped by a bundle.<id>.
subsection, where each key corresponding to a given <id>
contributes attributes to the bundle defined by that <id>. See
git-config(1) for the specific details of these keys and how
the Git client will interpret their values.
Clients MUST parse the line according to the above format,
lines that do not conform to the format SHOULD be discarded.
The user MAY be warned in such a case.
bundle-uri CLIENT AND SERVER EXPECTATIONS
URI CONTENTS
The content at the advertised URIs MUST be one of two
types.
The advertised URI may contain a bundle file that git
bundle verify would accept. I.e. they MUST contain one or
more reference tips for use by the client, MUST indicate
prerequisites (in any) with standard "-" prefixes, and
MUST indicate their "object-format", if applicable.
The advertised URI may alternatively contain a plaintext
file that git config --list would accept (with the --file
option). The key-value pairs in this list are in the
bundle.* namespace (see git-config(1)).
bundle-uri CLIENT ERROR RECOVERY
A client MUST above all gracefully degrade on errors,
whether that error is because of bad missing/data in the
bundle URI(s), because that client is too dumb to e.g.
understand and fully parse out bundle headers and their
prerequisite relationships, or something else.
Server operators should feel confident in turning on
"bundle-uri" and not worry if e.g. their CDN goes down
that clones or fetches will run into hard failures. Even
if the server bundle(s) are incomplete, or bad in some way
the client should still end up with a functioning
repository, just as if it had chosen not to use this
protocol extension.
All subsequent discussion on client and server interaction
MUST keep this in mind.
bundle-uri SERVER TO CLIENT
The ordering of the returned bundle uris is not
significant. Clients MUST parse their headers to discover
their contained OIDS and prerequisites. A client MUST
consider the content of the bundle(s) themselves and their
header as the ultimate source of truth.
A server MAY even return bundle(s) that don’t have any
direct relationship to the repository being cloned (either
through accident, or intentional "clever" configuration),
and expect a client to sort out what data they’d like from
the bundle(s), if any.
bundle-uri CLIENT TO SERVER
The client SHOULD provide reference tips found in the
bundle header(s) as have lines in any subsequent fetch
request. A client MAY also ignore the bundle(s) entirely
if doing so is deemed worse for some reason, e.g. if the
bundles can’t be downloaded, it doesn’t like the tips it
finds etc.
WHEN ADVERTISED BUNDLE(S) REQUIRE NO FURTHER NEGOTIATION
If after issuing bundle-uri and ls-refs, and getting the
header(s) of the bundle(s) the client finds that the ref
tips it wants can be retrieved entirely from advertised
bundle(s), the client MAY disconnect from the Git server.
The results of such a clone or fetch should be
indistinguishable from the state attained without using
bundle-uri.
EARLY CLIENT DISCONNECTIONS AND ERROR RECOVERY
A client MAY perform an early disconnect while still
downloading the bundle(s) (having streamed and parsed
their headers). In such a case the client MUST gracefully
recover from any errors related to finishing the download
and validation of the bundle(s).
I.e. a client might need to re-connect and issue a fetch
command, and possibly fall back to not making use of
bundle-uri at all.
This "MAY" behavior is specified as such (and not a
"SHOULD") on the assumption that a server advertising
bundle uris is more likely than not to be serving up a
relatively large repository, and to be pointing to URIs
that have a good chance of being in working order. A
client MAY e.g. look at the payload size of the bundles as
a heuristic to see if an early disconnect is worth it,
should falling back on a full "fetch" dialog be necessary.
WHEN ADVERTISED BUNDLE(S) REQUIRE FURTHER NEGOTIATION
A client SHOULD commence a negotiation of a PACK from the
server via the "fetch" command using the OID tips found in
advertised bundles, even if’s still in the process of
downloading those bundle(s).
This allows for aggressive early disconnects from any
interactive server dialog. The client blindly trusts that
the advertised OID tips are relevant, and issues them as
have lines, it then requests any tips it would like
(usually from the "ls-refs" advertisement) via want lines.
The server will then compute a (hopefully small) PACK with
the expected difference between the tips from the
bundle(s) and the data requested.
The only connection the client then needs to keep active
is to the concurrently downloading static bundle(s), when
those and the incremental PACK are retrieved they should
be inflated and validated. Any errors at this point should
be gracefully recovered from, see above.
bundle-uri PROTOCOL FEATURES
The client constructs a bundle list from the <key>=<value>
pairs provided by the server. These pairs are part of the
bundle.* namespace as documented in git-config(1). In this
section, we discuss some of these keys and describe the
actions the client will do in response to this information.
In particular, the bundle.version key specifies an integer
value. The only accepted value at the moment is 1, but if the
client sees an unexpected value here then the client MUST
ignore the bundle list.
As long as bundle.version is understood, all other unknown
keys MAY be ignored by the client. The server will guarantee
compatibility with older clients, though newer clients may be
better able to use the extra keys to minimize downloads.
Any backwards-incompatible addition of pre-URI key-value will
be guarded by a new bundle.version value or values in
bundle-uri capability advertisement itself, and/or by new
future bundle-uri request arguments.
Some example key-value pairs that are not currently
implemented but could be implemented in the future include:
• Add a "hash=<val>" or "size=<bytes>" advertise the
expected hash or size of the bundle file.
• Advertise that one or more bundle files are the same (to
e.g. have clients round-robin or otherwise choose one of N
possible files).
• A "oid=<OID>" shortcut and "prerequisite=<OID>" shortcut.
For expressing the common case of a bundle with one tip
and no prerequisites, or one tip and one prerequisite.
This would allow for optimizing the common case of servers
who’d like to provide one "big bundle" containing only
their "main" branch, and/or incremental updates thereof.
A client receiving such a response MAY assume that they
can skip retrieving the header from a bundle at the
indicated URI, and thus save themselves and the server(s)
the request(s) needed to inspect the headers of that
bundle or bundles.
promisor-remote=<pr-infos>
The server may advertise some promisor remotes it is using or
knows about to a client which may want to use them as its promisor
remotes, instead of this repository. In this case <pr-infos>
should be of the form:
pr-infos = pr-info | pr-infos ";" pr-info
pr-info = "name=" pr-name | "name=" pr-name "," "url=" pr-url
where pr-name is the urlencoded name of a promisor remote, and
pr-url the urlencoded URL of that promisor remote.
In this case, if the client decides to use one or more promisor
remotes the server advertised, it can reply with
"promisor-remote=<pr-names>" where <pr-names> should be of the
form:
pr-names = pr-name | pr-names ";" pr-name
where pr-name is the urlencoded name of a promisor remote the
server advertised and the client accepts.
Note that, everywhere in this document, pr-name MUST be a valid
remote name, and the ; and , characters MUST be encoded if they
appear in pr-name or pr-url.
If the server doesn’t know any promisor remote that could be good
for a client to use, or prefers a client not to use any promisor
remote it uses or knows about, it shouldn’t advertise the
"promisor-remote" capability at all.
In this case, or if the client doesn’t want to use any promisor
remote the server advertised, the client shouldn’t advertise the
"promisor-remote" capability at all in its reply.
The "promisor.advertise" and "promisor.acceptFromServer"
configuration options can be used on the server and client side to
control what they advertise or accept respectively. See the
documentation of these configuration options for more information.
Note that in the future it would be nice if the "promisor-remote"
protocol capability could be used by the server, when responding
to git fetch or git clone, to advertise better-connected remotes
that the client can use as promisor remotes, instead of this
repository, so that the client can lazily fetch objects from these
other better-connected remotes. This would require the server to
omit in its response the objects available on the better-connected
remotes that the client has accepted. This hasn’t been implemented
yet though. So for now this "promisor-remote" capability is useful
only when the server advertises some promisor remotes it already
uses to borrow objects from.
Part of the git(1) suite
1. api-trace2
file:///home/mtk/share/doc/git-doc/technical/api-trace2.html
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/git/git.git⟩ on 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-07.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Git 2.51.0.rc1 2025-08-07 GITPROTOCOL-V2(5)
Pages that refer to this page: git(1), git-config(1), git-upload-pack(1), gitformat-pack(5), gitprotocol-capabilities(5), gitprotocol-pack(5)
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