Subject: [HOWTO] Using post-update hook
Message-ID: <7vy86o6usx.fsf@assigned-by-dhcp.cox.net>
From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 26 Aug 2005 18:19:10 -0700
Abstract: In this how-to article, JC talks about how he
uses the post-update hook to automate Git documentation page
shown at http://www.kernel.org/pub/software/scm/git/docs/.
Content-type: text/asciidoc
How to rebuild from update hook
===============================
The pages under http://www.kernel.org/pub/software/scm/git/docs/
are built from Documentation/ directory of the git.git project
and needed to be kept up-to-date. The www.kernel.org/ servers
are mirrored and I was told that the origin of the mirror is on
the machine $some.kernel.org, on which I was given an account
when I took over Git maintainership from Linus.
The directories relevant to this how-to are these two:
/pub/scm/git/git.git/ The public Git repository.
/pub/software/scm/git/docs/ The HTML documentation page.
So I made a repository to generate the documentation under my
home directory over there.
$ cd
$ mkdir doc-git && cd doc-git
$ git clone /pub/scm/git/git.git/ docgen
What needs to happen is to update the $HOME/doc-git/docgen/
working tree, build HTML docs there and install the result in
/pub/software/scm/git/docs/ directory. So I wrote a little
script:
$ cat >dododoc.sh <<\EOF
#!/bin/sh
cd $HOME/doc-git/docgen || exit
unset GIT_DIR
git pull /pub/scm/git/git.git/ master &&
cd Documentation &&
make install-webdoc
EOF
Initially I used to run this by hand whenever I push into the
public Git repository. Then I did a cron job that ran twice a
day. The current round uses the post-update hook mechanism,
like this:
$ cat >/pub/scm/git/git.git/hooks/post-update <<\EOF
#!/bin/sh
#
# An example hook script to prepare a packed repository for use over
# dumb transports.
#
# To enable this hook, make this file executable by "chmod +x post-update".
case " $* " in
*' refs/heads/master '*)
echo $HOME/doc-git/dododoc.sh | at now
;;
esac
exec git-update-server-info
EOF
$ chmod +x /pub/scm/git/git.git/hooks/post-update
There are four things worth mentioning:
- The update-hook is run after the repository accepts a "git
push", under my user privilege. It is given the full names
of refs that have been updated as arguments. My post-update
runs the dododoc.sh script only when the master head is
updated.
- When update-hook is run, GIT_DIR is set to '.' by the calling
receive-pack. This is inherited by the dododoc.sh run via
the "at" command, and needs to be unset; otherwise, "git
pull" it does into $HOME/doc-git/docgen/ repository would not
work correctly.
- The stdout of update hook script is not connected to git
push; I run the heavy part of the command inside "at", to
receive the execution report via e-mail.
- This is still crude and does not protect against simultaneous
make invocations stomping on each other. I would need to add
some locking mechanism for this.