1 files changed, 27 insertions, 0 deletions
diff --git a/nixpkgs/pkgs/build-support/docker/store-path-to-layer.sh b/nixpkgs/pkgs/build-support/docker/store-path-to-layer.sh
new file mode 100755
index 000000000000..bcad9e83e06f
--- /dev/null
+++ b/nixpkgs/pkgs/build-support/docker/store-path-to-layer.sh
@@ -0,0 +1,27 @@
+#!@shell@
+
+set -eu
+
+layerNumber=$1
+shift
+
+layerPath="./layers/$layerNumber"
+echo "Creating layer #$layerNumber for $@"
+
+mkdir -p "$layerPath"
+tar --no-recursion -rf "$layerPath/layer.tar" \
+    --mtime="@$SOURCE_DATE_EPOCH" \
+    --owner=0 --group=0 /nix /nix/store
+tar -rpf "$layerPath/layer.tar" --hard-dereference --sort=name \
+    --mtime="@$SOURCE_DATE_EPOCH" \
+    --owner=0 --group=0 "$@"
+
+# Compute a checksum of the tarball.
+tarhash=$(tarsum < $layerPath/layer.tar)
+
+# Add a 'checksum' field to the JSON, with the value set to the
+# checksum of the tarball.
+cat ./generic.json | jshon -s "$tarhash" -i checksum > $layerPath/json
+
+# Indicate to docker that we're using schema version 1.0.
+echo -n "1.0" > $layerPath/VERSION