Make reproducible tarballs with dist

2 files changed, 46 insertions, 4 deletions

diff --git a/lib/actions/dist.bash b/lib/actions/dist.bash
index 727cb53..137576d 100644
--- a/lib/actions/dist.bash
+++ b/lib/actions/dist.bash
@@ -13,9 +13,25 @@ RSTAR_DEPS_BIN+=(
 )
 
 action() {
-	local version="${1:-$(date +%Y.%m)}"
+	local LC_ALL
+	local SOURCE_DATE_EPOCH
+	local basename
+	local tarball
+	local version
+
+	# Prepare environment for a reproducible tarball
+	LC_ALL=C.UTF-8
+	SOURCE_DATE_EPOCH="$(git log -1 --pretty=format:%at)"
+
+	# Set a version if none was specified explicitly
+	version="${1:-$(datetime %Y.%m)}"
 	WORKDIR="$BASEDIR/tmp/rakudo-star-$version"
 
+	debug "SOURCE_DATE_EPOCH set to $SOURCE_DATE_EPOCH"
+
+	export LC_ALL
+	export SOURCE_DATE_EPOCH
+
 	info "Creating distribution contents at $WORKDIR"
 
 	chgdir "$BASEDIR"
@@ -31,17 +47,27 @@ action() {
 
 	# Add a MANIFEST.txt
 	chgdir "$WORKDIR"
-	find . > MANIFEST.txt
+	touch MANIFEST.txt
+	find . -type f | sed 's|^./||' | sort > MANIFEST.txt
 
 	# Tar it all up into a distribution tarball
 	info "Creating tarball out of $WORKDIR"
 
-	local tarball="$BASEDIR/dist/rakudo-star-$version.tar.gz"
+	basename="rakudo-star-$version"
+	tarball="$BASEDIR/dist/$basename.tar.gz"
 
 	mkdir -p -- "$(dirname "$tarball")"
 	chgdir "$BASEDIR/tmp"
 
-	tar czf "$tarball" "rakudo-star-$version"
+	awk '{ print "'"$basename"'/"$0 }' "$WORKDIR/MANIFEST.txt" \
+		| tar -c -T - \
+			--mtime @"$SOURCE_DATE_EPOCH" \
+			--mode=go=rX,u+rw,a-s \
+			--format=gnu \
+			--numeric-owner --owner=0 --group=0 \
+		| gzip -9cn \
+		> "$tarball"
+	touch -d"$(datetime)" "$tarball"
 
 	chgdir "$(dirname "$tarball")"
 
diff --git a/lib/util.bash b/lib/util.bash
index 97131c3..a387d8b 100644
--- a/lib/util.bash
+++ b/lib/util.bash
@@ -33,6 +33,22 @@ config_etc_kv() {
 	printf "%s" "$value"
 }
 
+# Create a datetime stamp. This is a wrapper around the date utility, ensuring
+# that the date being formatted is always in UTC and respect SOURCE_DATE_EPOCH,
+# if it is set.
+datetime() {
+	local date_opts
+
+	# Apply SOURCE_DATE_EPOCH as the date to base off of.
+	if [[ $SOURCE_DATE_EPOCH ]]
+	then
+		date_opts+=("-d@$SOURCE_DATE_EPOCH")
+		date_opts+=("-u")
+	fi
+
+	date "${date_opts[@]}" +"${1:-%FT%T}"
+}
+
 # Log a message as error, and exit the program. This is intended for serious
 # issues that prevent the script from running correctly. The exit code can be
 # specified with -i, or will default to 1.