generate-stackbrew-library.sh

#!/bin/bash
set -eu

self="$(basename "$BASH_SOURCE")"
cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"

# get the most recent commit which modified any of "$@"
fileCommit() {
	git log -1 --format='format:%H' HEAD -- "$@"
}

# 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
					}
				}
			')
	)
}

getArches() {
	local repo="$1"; shift
	local officialImagesUrl='https://github.com/docker-library/official-images/raw/master/library/'

	eval "declare -g -A parentRepoToArches=( $(
		find -name 'Dockerfile' -exec awk '
				toupper($1) == "FROM" && $2 !~ /^('"$repo"'|scratch|.*\/.*)(:|$)/ {
					print "'"$officialImagesUrl"'" $2
				}
			' '{}' + \
			| sort -u \
			| xargs bashbrew cat --format '[{{ .RepoName }}:{{ .TagName }}]="{{ join " " .TagEntry.Architectures }}"'
	) )"
}
getArches 'memcached'

cat <<-EOH
# this file is generated via https://github.com/docker-library/memcached/blob/$(fileCommit "$self")/$self

Maintainers: Tianon Gravi <admwiggin@gmail.com> (@tianon),
             Joseph Ferguson <yosifkit@gmail.com> (@yosifkit)
GitRepo: https://github.com/docker-library/memcached.git
EOH

# prints "$2$1$3$1...$N"
join() {
	local sep="$1"; shift
	local out; printf -v out "${sep//%/%%}%s" "$@"
	echo "${out#$sep}"
}

for variant in debian alpine; do
	commit="$(dirCommit "$variant")"

	fullVersion="$(git show "$commit":"$variant/Dockerfile" | awk '$1 == "ENV" && $2 == "MEMCACHED_VERSION" { print $3; exit }')"

	versionAliases=()
	while [ "${fullVersion%.*}" != "$fullVersion" ]; do
		versionAliases+=( $fullVersion )
		fullVersion="${fullVersion%.*}"
	done
	versionAliases+=(
		$fullVersion
		latest
	)

	if [ "$variant" = 'debian' ]; then
		variantAliases=( "${versionAliases[@]}" )
	else
		variantAliases=( "${versionAliases[@]/%/-$variant}" )
		variantAliases=( "${variantAliases[@]//latest-/}" )
	fi

	parent="$(awk 'toupper($1) == "FROM" { print $2 }' "$variant/Dockerfile")"

	suite="${parent#*:}" # "bullseye-slim", "bullseye"
	suite="${suite%-slim}" # "bullseye"
	if [ "$variant" = 'alpine' ]; then
		suite="alpine$suite" # "alpine3.14"
		suiteAliases=( "${versionAliases[@]/%/-$suite}" )
	else
		suiteAliases=( "${variantAliases[@]/%/-$suite}" )
	fi
	suiteAliases=( "${suiteAliases[@]//latest-/}" )
	variantAliases+=( "${suiteAliases[@]}" )

	arches="${parentRepoToArches[$parent]}"

	# https://github.com/memcached/memcached/issues/799
	# https://github.com/docker-library/memcached/issues/69
	arches="$(sed -r -e 's/ arm32v6 / /g' <<<" $arches ")"

	echo
	cat <<-EOE
		Tags: $(join ', ' "${variantAliases[@]}")
		Architectures: $(join ', ' $arches)
		GitCommit: $commit
		Directory: $variant
	EOE
done