function library for git hooks & a post-receive hook for automatic branch building

git-hook-functions.sh

#!/bin/bash

GIT_DIR=$(git rev-parse --git-dir 2>/dev/null)
if [ -z "$GIT_DIR" ]; then
	echo >&2 "fatal: hooks/functions: GIT_DIR not set"
	exit 1
fi

read oldrev newrev refname

# --- Interpret
# 0000->1234 (create)
# 1234->2345 (update)
# 2345->0000 (delete)
if expr "$oldrev" : '0*$' >/dev/null
then
	change_type="create"
else
	if expr "$newrev" : '0*$' >/dev/null
	then
		change_type="delete"
	else
		change_type="update"
	fi
fi

# --- Get the revision types
newrev_type=$(git cat-file -t $newrev 2> /dev/null)
oldrev_type=$(git cat-file -t "$oldrev" 2> /dev/null)
case "$change_type" in
create|update)
	rev="$newrev"
	rev_type="$newrev_type"
	;;
delete)
	rev="$oldrev"
	rev_type="$oldrev_type"
	;;
esac

# The revision type tells us what type the commit is, combined with
# the location of the ref we can decide between
#  - working branch
#  - tracking branch
#  - unannoted tag
#  - annotated tag
case "$refname","$rev_type" in
	refs/tags/*,commit)
		# un-annotated tag
		refname_type="tag"
		short_refname=${refname##refs/tags/}
		;;
	refs/tags/*,tag)
		# annotated tag
		refname_type="annotated tag"
		short_refname=${refname##refs/tags/}
		# change recipients
		if [ -n "$announcerecipients" ]; then
			recipients="$announcerecipients"
		fi
		;;
	refs/heads/*,commit)
		# branch
		refname_type="branch"
		short_refname=${refname##refs/heads/}
		;;
	refs/remotes/*,commit)
		# tracking branch
		refname_type="tracking branch"
		short_refname=${refname##refs/remotes/}
		;;
	*)
		# Anything else (is there anything else?)
		refname_type="unknown"
		;;
esac

describe=$(git describe $rev 2>/dev/null)
if [ -z "$describe" ]; then
	describe=$rev
fi

projectdesc=$(sed -ne '1p' "$GIT_DIR/description")
# Check if the description is unchanged from it's default, and shorten it to
# a more manageable length if it is
if expr "$projectdesc" : "Unnamed repository.*$" >/dev/null
then
	projectdesc="UNNAMED PROJECT"
fi

# some email helpers
recipients=$(git config hooks.mailinglist)
announcerecipients=$(git config hooks.announcelist)
envelopesender=$(git config hooks.envelopesender)
emailprefix=$(git config hooks.emailprefix || echo '[SCM] ')
custom_showrev=$(git config hooks.showrev)

# get the name of the target branch for builds
regex='refs/heads/(.*)'
if [[ $refname =~ $regex ]]; then
	target_branch="${BASH_REMATCH[1]}"
fi

# how to spawn builds in jenkins
jenkins_url="http://jenkins//job"
jenkins_token="SEEEKRIT"
	
get_autobuild_options() {
	configfile_hash=$(git ls-tree $newrev | grep autobuild.cfg | cut -d' ' -f 3 | cut -f 1 )
	if [[ "$configfile_hash" != "" ]] ; then
		autobuild_options=$( git cat-file blob "$configfile_hash" | egrep -i "^\s*${target_branch}=" | cut -d= -f 2 )
		echo "autobuild options detected: '${autobuild_options}'"
		autobuild_enabled=$( echo "$autobuild_options" | grep '\<autobuild\>' )
	fi
}

post-receive.sh

job="MyJenkinsJob"

# load the git hook functions library
. git-hook-functions.sh

# read the autobuild configuration
get_autobuild_options

if [[ $autobuild_enabled ]] ; then
	function trigger_build {
		echo "Automatically scheduling new build against origin/$target_branch: $jenkins_url/$job"
		wget -q -O - "$jenkins_url/$job/buildWithParameters?token=$jenkins_token&BRANCH=$target_branch" > /dev/null
	}

	case "$change_type" in
		create)
			if expr "$newrev" : '0*$' >/dev/null; then
				echo "$refname is newly created, so not triggering a build."
			else
				trigger_build
			fi
			;;
		update)
			trigger_build
			;;
		delete)
			echo "$refname is being deleted, so not triggering a build."
			;;
	esac
fi