Update to use newer manifest file format (#233)

The new format is base on based on RFC 2822.

See:

https://github.com/docker-library/official-images#instruction-format

Also:

* No longer hardcodes the variant names (onbuild slim wheezy)
* Sorts version numbers which puts the higher version numbers first
* Adds link to generate-stackbrew-library.sh in manifest header
* Don't script against `ls` when determining variants
* And some other code improvements

generate-stackbrew-library.sh

@@ -9,37 +9,62 @@ array_6_6='6 latest';
 
 cd $(cd ${0%/*} && pwd -P);
 
+self="$(basename "$BASH_SOURCE")"
+
 versions=( */ )
 versions=( "${versions[@]%/}" )
-url='git://github.com/nodejs/docker-node'
+url='https://github.com/nodejs/docker-node'
 
-echo '# maintainer: Node.js Docker Team <https://github.com/nodejs/docker-node> (@nodejs)'
+# sort version numbers with highest first
+IFS=$'\n'; versions=( $(echo "${versions[*]}" | sort -r) ); unset IFS
+
+# get the most recent commit which modified any of "$@"
+fileCommit() {
+	git log -1 --format='format:%H' HEAD -- "$@"
+}
+
+echo "# this file is generated via ${url}/blob/$(fileCommit "$self")/$self"
+echo
+echo "Maintainers: The Node.js Docker Team <${url}> (@nodejs)"
+echo "GitRepo: ${url}.git"
+echo
+
+# prints "$2$1$3$1...$N"
+join() {
+	local sep="$1"; shift
+	local out; printf -v out "${sep//%/%%}%s" "$@"
+	echo "${out#$sep}"
+}
 
 for version in "${versions[@]}"; do
-	if [[ "$version" == "docs" ]]; then
-		continue
-	fi
+	# Skip "docs" and other non-docker directories
+	[ -f "$version/Dockerfile" ] || continue
+	
 	eval stub=$(echo "$version" | awk -F. '{ print "$array_" $1 "_" $2 }');
-	commit="$(git log -1 --format='format:%H' -- "$version")"
+	commit="$(fileCommit "$version")"
 	fullVersion="$(grep -m1 'ENV NODE_VERSION ' "$version/Dockerfile" | cut -d' ' -f3)"
 
 	versionAliases=( $fullVersion $version ${stub} )
-
+	
+	echo "Tags: $(join ', ' "${versionAliases[@]}")"
+	echo "GitCommit: ${commit}"
+	echo "Directory: ${version}"
 	echo
-	for va in "${versionAliases[@]}"; do
-		echo "$va: ${url}@${commit} $version"
-	done
 
-	for variant in onbuild slim wheezy; do
-		commit="$(git log -1 --format='format:%H' -- "$version/$variant")"
+	variants=$(echo $version/*/ | xargs -n1 basename)
+	for variant in $variants; do
+		# Skip non-docker directories
+		[ -f "$version/$variant/Dockerfile" ] || continue
+		
+		commit="$(fileCommit "$version/$variant")"
+		
+		slash='/'
+		variantAliases=( "${versionAliases[@]/%/-${variant//$slash/-}}" )
+		variantAliases=( "${variantAliases[@]//latest-/}" )
+
+		echo "Tags: $(join ', ' "${variantAliases[@]}")"
+		echo "GitCommit: ${commit}"
+		echo "Directory: ${version}/${variant}"
 		echo
-		for va in "${versionAliases[@]}"; do
-			if [ "$va" = 'latest' ]; then
-				va="$variant"
-			else
-				va="$va-$variant"
-			fi
-			echo "$va: ${url}@${commit} $version/$variant"
-		done
 	done
 done