Convert "generate-stackbrew-library.sh" to output the new 2822-based format

Author: yosifkit

generate-stackbrew-library.sh

@@ -1,14 +1,49 @@
 #!/bin/bash
-set -e
+set -eu
 
+self="$(basename "$BASH_SOURCE")"
 cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 
-url='git://github.com/docker-library/rails'
+# get the most recent commit which modified any of "$@"
+fileCommit() {
+	git log -1 --format='format:%H' HEAD -- "$@"
+}
 
-echo '# maintainer: InfoSiftr <[email protected]> (@infosiftr)'
+# get the most recent commit which modified "$1/Dockerfile" or any file COPY'd from "$1/Dockerfile"
+dirCommit() {
+	local dir="$1"; shift
+	(
+		cd "$dir"
+		fileCommit \
+			Dockerfile \
+			$(git show HEAD:./Dockerfile | awk '
+				toupper($1) == "COPY" {
+					for (i = 2; i < NF; i++) {
+						print $i
+					}
+				}
+			')
+	)
+}
 
-commit="$(git log -1 --format='format:%H' -- Dockerfile $(awk 'toupper($1) == "COPY" { for (i = 2; i < NF; i++) { print $i } }' Dockerfile))"
-fullVersion="$(grep -m1 'ENV RAILS_VERSION ' Dockerfile | cut -d' ' -f3)"
+cat <<-EOH
+# this file is generated via https://github.com/docker-library/rails/blob/$(fileCommit "$self")/$self
+
+Maintainers: Tianon Gravi <[email protected]> (@tianon),
+             Joseph Ferguson <[email protected]> (@yosifkit)
+GitRepo: https://github.com/docker-library/rails.git
+EOH
+
+# prints "$2$1$3$1...$N"
+join() {
+	local sep="$1"; shift
+	local out; printf -v out "${sep//%/%%}%s" "$@"
+	echo "${out#$sep}"
+}
+
+commit="$(dirCommit .)"
+
+fullVersion="$(git show "$commit":Dockerfile | awk '$1 == "ENV" && $2 == "RAILS_VERSION" { print $3; exit }')"
 
 versionAliases=()
 while [ "${fullVersion%.*}" != "$fullVersion" ]; do
@@ -18,12 +53,20 @@ done
 versionAliases+=( $fullVersion latest )
 
 echo
-for va in "${versionAliases[@]}"; do
-	echo "$va: ${url}@${commit}"
-done
+cat <<-EOE
+	Tags: $(join ', ' "${versionAliases[@]}")
+	GitCommit: $commit
+EOE
 
 for variant in onbuild; do
+	commit="$(dirCommit "$variant")"
+
+	variantAliases=( "$variant" )
+
 	echo
-	commit="$(cd "$variant" && git log -1 --format='format:%H' -- Dockerfile $(awk 'toupper($1) == "COPY" { for (i = 2; i < NF; i++) { print $i } }' Dockerfile))"
-	echo "$variant: ${url}@${commit} $variant"
+	cat <<-EOE
+		Tags: $(join ', ' "${variantAliases[@]}")
+		GitCommit: $commit
+		Directory: $variant
+	EOE
 done