Add install-static element

This element currently exists in tripleo-image-elements but it is plenty
useful without tripleo.

Change-Id: I2415f53191773fafece485bdd3c706a2625a0a47

elements/install-static/README.md

@@ -0,0 +1,7 @@
+Copy static files into the built image.
+
+The contents of any ``static/`` subdirs of elements will be installed into
+these images at build time using ``rsync -lCr``. So to install a file
+``/etc/boo``, include ``static/etc/boo`` in your element.
+
+Note: This installs all files with owner and group of root.

elements/install-static/install.d/10-install-static-files

@@ -0,0 +1,11 @@
+#!/bin/bash
+# Note that this relies on the detail that all elements share one dir inside
+# the chroot. This will copy all the files that elements have added to
+# element/static into the image. Mode, symlinks etc will be respected.
+set -eux
+set -o pipefail
+
+STATIC_SOURCE="$(dirname $0)/../static"
+[ -d "${STATIC_SOURCE}" ] || exit 0
+
+rsync -lCr "${STATIC_SOURCE}"/ /