ubuntu-cpc: Reintroduce the -root.tar.xz artifact (LP: #1585233).

debian/changelog

@@ -1,3 +1,9 @@
+livecd-rootfs (2.530) UNRELEASED; urgency=medium
+
+  * ubuntu-cpc: Reintroduce the -root.tar.xz artifact (LP: #1585233).
+
+ -- Daniel Watkins <oddbloke@ubuntu.com>  Wed, 06 Jun 2018 11:21:57 -0700
+
 livecd-rootfs (2.529) cosmic; urgency=medium
 
   * Improvements to the ubuntu-base (i.e. Docker) build:

live-build/ubuntu-cpc/hooks/031-root-xz.binary

@@ -0,0 +1,30 @@
+#!/bin/bash -ex
+# vi: ts=4 expandtab
+#
+# Generate the rootfs.tar.xz and manifest
+
+if [ -n "$SUBARCH" ]; then
+    echo "Skipping rootfs build for subarch flavor build"
+    exit 0
+fi
+
+. /build/config/functions
+
+tardir=filesystem.dir
+mkdir $tardir
+cp -a chroot/* $tardir
+
+setup_mountpoint $tardir
+
+env DEBIAN_FRONTEND=noninteractive chroot $tardir apt-get --purge remove --assume-yes '^linux-.*' 'linux-base+'
+env DEBIAN_FRONTEND=noninteractive chroot $tardir apt-get --purge remove --assume-yes '^grub-.*'
+env DEBIAN_FRONTEND=noninteractive chroot $tardir apt-get autoremove --purge --assume-yes
+chroot $tardir mkdir -p /lib/modules
+
+teardown_mountpoint $tardir
+
+dpkg-query --admindir=$tardir/var/lib/dpkg -W > livecd.ubuntu-cpc.rootfs.manifest
+
+(cd "$tardir/" && tar -c *) | xz > "livecd.ubuntu-cpc.rootfs.tar.xz"
+
+rm -rf $tardir