Documentation/howto/rebuild-from-update-hook.txt

   1 Subject: [HOWTO] Using post-update hook
   2 Message-ID: <7vy86o6usx.fsf@assigned-by-dhcp.cox.net>
   3 From: Junio C Hamano <junkio@cox.net>
   4 Date: Fri, 26 Aug 2005 18:19:10 -0700
   5 Abstract: In this how-to article, JC talks about how he
   6  uses the post-update hook to automate git documentation page
   7  shown at http://www.kernel.org/pub/software/scm/git/docs/.
   8
   9 The pages under http://www.kernel.org/pub/software/scm/git/docs/
  10 are built from Documentation/ directory of the git.git project
  11 and needed to be kept up-to-date.  The www.kernel.org/ servers
  12 are mirrored and I was told that the origin of the mirror is on
  13 the machine $some.kernel.org, on which I was given an account
  14 when I took over git maintainership from Linus.
  15
  16 The directories relevant to this how-to are these two:
  17
  18     /pub/scm/git/git.git/       The public git repository.
  19     /pub/software/scm/git/docs/ The HTML documentation page.
  20
  21 So I made a repository to generate the documentation under my
  22 home directory over there.
  23
  24     $ cd
  25     $ mkdir doc-git && cd doc-git
  26     $ git clone /pub/scm/git/git.git/ docgen
  27
  28 What needs to happen is to update the $HOME/doc-git/docgen/
  29 working tree, build HTML docs there and install the result in
  30 /pub/software/scm/git/docs/ directory.  So I wrote a little
  31 script:
  32
  33     $ cat >dododoc.sh <<\EOF
  34     #!/bin/sh
  35     cd $HOME/doc-git/docgen || exit
  36
  37     unset GIT_DIR
  38
  39     git pull /pub/scm/git/git.git/ master &&
  40     cd Documentation &&
  41     make install-webdoc
  42     EOF
  43
  44 Initially I used to run this by hand whenever I push into the
  45 public git repository.  Then I did a cron job that ran twice a
  46 day.  The current round uses the post-update hook mechanism,
  47 like this:
  48
  49     $ cat >/pub/scm/git/git.git/hooks/post-update <<\EOF
  50     #!/bin/sh
  51     #
  52     # An example hook script to prepare a packed repository for use over
  53     # dumb transports.
  54     #
  55     # To enable this hook, make this file executable by "chmod +x post-update".
  56
  57     case " $* " in
  58     *' refs/heads/master '*)
  59             echo $HOME/doc-git/dododoc.sh | at now
  60             ;;
  61     esac
  62     exec git-update-server-info
  63     EOF
  64     $ chmod +x /pub/scm/git/git.git/hooks/post-update
  65
  66 There are four things worth mentioning:
  67
  68  - The update-hook is run after the repository accepts a "git
  69    push", under my user privilege.  It is given the full names
  70    of refs that have been updated as arguments.  My post-update
  71    runs the dododoc.sh script only when the master head is
  72    updated.
  73
  74  - When update-hook is run, GIT_DIR is set to '.' by the calling
  75    receive-pack.  This is inherited by the dododoc.sh run via
  76    the "at" command, and needs to be unset; otherwise, "git
  77    pull" it does into $HOME/doc-git/docgen/ repository would not
  78    work correctly.
  79
  80  - The stdout of update hook script is not connected to git
  81    push; I run the heavy part of the command inside "at", to
  82    receive the execution report via e-mail.
  83
  84  - This is still crude and does not protect against simultaneous
  85    make invocations stomping on each other.  I would need to add
  86    some locking mechanism for this.