Documentation/git-receive-pack.txt

   1 git-receive-pack(1)
   2 ===================
   3
   4 NAME
   5 ----
   6 git-receive-pack - Receive what is pushed into the repository
   7
   8
   9 SYNOPSIS
  10 --------
  11 [verse]
  12 'git-receive-pack' <directory>
  13
  14 DESCRIPTION
  15 -----------
  16 Invoked by 'git send-pack' and updates the repository with the
  17 information fed from the remote end.
  18
  19 This command is usually not invoked directly by the end user.
  20 The UI for the protocol is on the 'git send-pack' side, and the
  21 program pair is meant to be used to push updates to remote
  22 repository.  For pull operations, see linkgit:git-fetch-pack[1].
  23
  24 The command allows for creation and fast-forwarding of sha1 refs
  25 (heads/tags) on the remote end (strictly speaking, it is the
  26 local end 'git-receive-pack' runs, but to the user who is sitting at
  27 the send-pack end, it is updating the remote.  Confused?)
  28
  29 There are other real-world examples of using update and
  30 post-update hooks found in the Documentation/howto directory.
  31
  32 'git-receive-pack' honours the receive.denyNonFastForwards config
  33 option, which tells it if updates to a ref should be denied if they
  34 are not fast-forwards.
  35
  36 A number of other receive.* config options are available to tweak
  37 its behavior, see linkgit:git-config[1].
  38
  39 OPTIONS
  40 -------
  41 <directory>::
  42         The repository to sync into.
  43
  44 PRE-RECEIVE HOOK
  45 ----------------
  46 Before any ref is updated, if $GIT_DIR/hooks/pre-receive file exists
  47 and is executable, it will be invoked once with no parameters.  The
  48 standard input of the hook will be one line per ref to be updated:
  49
  50        sha1-old SP sha1-new SP refname LF
  51
  52 The refname value is relative to $GIT_DIR; e.g. for the master
  53 head this is "refs/heads/master".  The two sha1 values before
  54 each refname are the object names for the refname before and after
  55 the update.  Refs to be created will have sha1-old equal to 0\{40},
  56 while refs to be deleted will have sha1-new equal to 0\{40}, otherwise
  57 sha1-old and sha1-new should be valid objects in the repository.
  58
  59 When accepting a signed push (see linkgit:git-push[1]), the signed
  60 push certificate is stored in a blob and an environment variable
  61 `GIT_PUSH_CERT` can be consulted for its object name.  See the
  62 description of `post-receive` hook for an example.  In addition, the
  63 certificate is verified using GPG and the result is exported with
  64 the following environment variables:
  65
  66 `GIT_PUSH_CERT_SIGNER`::
  67         The name and the e-mail address of the owner of the key that
  68         signed the push certificate.
  69
  70 `GIT_PUSH_CERT_KEY`::
  71         The GPG key ID of the key that signed the push certificate.
  72
  73 `GIT_PUSH_CERT_STATUS`::
  74         The status of GPG verification of the push certificate,
  75         using the same mnemonic as used in `%G?` format of `git log`
  76         family of commands (see linkgit:git-log[1]).
  77
  78 `GIT_PUSH_CERT_NONCE`::
  79         The nonce string the process asked the signer to include
  80         in the push certificate.  If this does not match the value
  81         recorded on the "nonce" header in the push certificate, it
  82         may indicate that the certificate is a valid one that is
  83         being replayed from a separate "git push" session.
  84
  85 `GIT_PUSH_CERT_NONCE_STATUS`::
  86 `UNSOLICITED`;;
  87         "git push --signed" sent a nonce when we did not ask it to
  88         send one.
  89 `MISSING`;;
  90         "git push --signed" did not send any nonce header.
  91 `BAD`;;
  92         "git push --signed" sent a bogus nonce.
  93 `OK`;;
  94         "git push --signed" sent the nonce we asked it to send.
  95 `SLOP`;;
  96         "git push --signed" sent a nonce different from what we
  97         asked it to send now, but in a previous session.  See
  98         `GIT_PUSH_CERT_NONCE_SLOP` environment variable.
  99
 100 `GIT_PUSH_CERT_NONCE_SLOP`::
 101         "git push --signed" sent a nonce different from what we
 102         asked it to send now, but in a different session whose
 103         starting time is different by this many seconds from the
 104         current session.  Only meaningful when
 105         `GIT_PUSH_CERT_NONCE_STATUS` says `SLOP`.
 106         Also read about `receive.certNonceSlop` variable in
 107         linkgit:git-config[1].
 108
 109 This hook is called before any refname is updated and before any
 110 fast-forward checks are performed.
 111
 112 If the pre-receive hook exits with a non-zero exit status no updates
 113 will be performed, and the update, post-receive and post-update
 114 hooks will not be invoked either.  This can be useful to quickly
 115 bail out if the update is not to be supported.
 116
 117 See the notes on the quarantine environment below.
 118
 119 UPDATE HOOK
 120 -----------
 121 Before each ref is updated, if $GIT_DIR/hooks/update file exists
 122 and is executable, it is invoked once per ref, with three parameters:
 123
 124        $GIT_DIR/hooks/update refname sha1-old sha1-new
 125
 126 The refname parameter is relative to $GIT_DIR; e.g. for the master
 127 head this is "refs/heads/master".  The two sha1 arguments are
 128 the object names for the refname before and after the update.
 129 Note that the hook is called before the refname is updated,
 130 so either sha1-old is 0\{40} (meaning there is no such ref yet),
 131 or it should match what is recorded in refname.
 132
 133 The hook should exit with non-zero status if it wants to disallow
 134 updating the named ref.  Otherwise it should exit with zero.
 135
 136 Successful execution (a zero exit status) of this hook does not
 137 ensure the ref will actually be updated, it is only a prerequisite.
 138 As such it is not a good idea to send notices (e.g. email) from
 139 this hook.  Consider using the post-receive hook instead.
 140
 141 POST-RECEIVE HOOK
 142 -----------------
 143 After all refs were updated (or attempted to be updated), if any
 144 ref update was successful, and if $GIT_DIR/hooks/post-receive
 145 file exists and is executable, it will be invoked once with no
 146 parameters.  The standard input of the hook will be one line
 147 for each successfully updated ref:
 148
 149        sha1-old SP sha1-new SP refname LF
 150
 151 The refname value is relative to $GIT_DIR; e.g. for the master
 152 head this is "refs/heads/master".  The two sha1 values before
 153 each refname are the object names for the refname before and after
 154 the update.  Refs that were created will have sha1-old equal to
 155 0\{40}, while refs that were deleted will have sha1-new equal to
 156 0\{40}, otherwise sha1-old and sha1-new should be valid objects in
 157 the repository.
 158
 159 The `GIT_PUSH_CERT*` environment variables can be inspected, just as
 160 in `pre-receive` hook, after accepting a signed push.
 161
 162 Using this hook, it is easy to generate mails describing the updates
 163 to the repository.  This example script sends one mail message per
 164 ref listing the commits pushed to the repository, and logs the push
 165 certificates of signed pushes with good signatures to a logger
 166 service:
 167
 168 ----
 169 #!/bin/sh
 170 # mail out commit update information.
 171 while read oval nval ref
 172 do
 173         if expr "$oval" : '0*$' >/dev/null
 174         then
 175                 echo "Created a new ref, with the following commits:"
 176                 git rev-list --pretty "$nval"
 177         else
 178                 echo "New commits:"
 179                 git rev-list --pretty "$nval" "^$oval"
 180         fi |
 181         mail -s "Changes to ref $ref" commit-list@mydomain
 182 done
 183 # log signed push certificate, if any
 184 if test -n "${GIT_PUSH_CERT-}" && test ${GIT_PUSH_CERT_STATUS} = G
 185 then
 186         (
 187                 echo expected nonce is ${GIT_PUSH_NONCE}
 188                 git cat-file blob ${GIT_PUSH_CERT}
 189         ) | mail -s "push certificate from $GIT_PUSH_CERT_SIGNER" push-log@mydomain
 190 fi
 191 exit 0
 192 ----
 193
 194 The exit code from this hook invocation is ignored, however a
 195 non-zero exit code will generate an error message.
 196
 197 Note that it is possible for refname to not have sha1-new when this
 198 hook runs.  This can easily occur if another user modifies the ref
 199 after it was updated by 'git-receive-pack', but before the hook was able
 200 to evaluate it.  It is recommended that hooks rely on sha1-new
 201 rather than the current value of refname.
 202
 203 POST-UPDATE HOOK
 204 ----------------
 205 After all other processing, if at least one ref was updated, and
 206 if $GIT_DIR/hooks/post-update file exists and is executable, then
 207 post-update will be called with the list of refs that have been updated.
 208 This can be used to implement any repository wide cleanup tasks.
 209
 210 The exit code from this hook invocation is ignored; the only thing
 211 left for 'git-receive-pack' to do at that point is to exit itself
 212 anyway.
 213
 214 This hook can be used, for example, to run `git update-server-info`
 215 if the repository is packed and is served via a dumb transport.
 216
 217 ----
 218 #!/bin/sh
 219 exec git update-server-info
 220 ----
 221
 222
 223 QUARANTINE ENVIRONMENT
 224 ----------------------
 225
 226 When `receive-pack` takes in objects, they are placed into a temporary
 227 "quarantine" directory within the `$GIT_DIR/objects` directory and
 228 migrated into the main object store only after the `pre-receive` hook
 229 has completed. If the push fails before then, the temporary directory is
 230 removed entirely.
 231
 232 This has a few user-visible effects and caveats:
 233
 234   1. Pushes which fail due to problems with the incoming pack, missing
 235      objects, or due to the `pre-receive` hook will not leave any
 236      on-disk data. This is usually helpful to prevent repeated failed
 237      pushes from filling up your disk, but can make debugging more
 238      challenging.
 239
 240   2. Any objects created by the `pre-receive` hook will be created in
 241      the quarantine directory (and migrated only if it succeeds).
 242
 243   3. The `pre-receive` hook MUST NOT update any refs to point to
 244      quarantined objects. Other programs accessing the repository will
 245      not be able to see the objects (and if the pre-receive hook fails,
 246      those refs would become corrupted). For safety, any ref updates
 247      from within `pre-receive` are automatically rejected.
 248
 249
 250 SEE ALSO
 251 --------
 252 linkgit:git-send-pack[1], linkgit:gitnamespaces[7]
 253
 254 GIT
 255 ---
 256 Part of the linkgit:git[1] suite