dracut/ignition-ostree: Regenerate UUIDs for /boot and /

This is a general best practice; the intention of filesystem
UUIDs is that they're unique.  It helps backup systems and the like
if we change this.

This builds on coreos/coreos-assembler@e3905fd

In the future, we may also switch to using these UUIDs for subsequent
boots; see: coreos/fedora-coreos-tracker#465

overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/ignition-ostree-firstboot-uuid

@@ -0,0 +1,42 @@
+#!/bin/bash
+set -euo pipefail
+# https://github.com/coreos/fedora-coreos-tracker/issues/465
+# coreos-assembler generates disk images which are installed bit-for-bit
+# or booted directly in the cloud.
+# Generate new UUID on firstboot; this is general best practice, but in the future
+# we may use this for mounting by e.g. adding a boot=<uuid> and root=<uuid> kernel args.
+# Note this code should be changed when we land https://github.com/coreos/fedora-coreos-tracker/issues/94
+# so that we only generate a new UUID if we're using the default one.
+
+label=$1
+
+# Keep this in sync with https://github.com/coreos/coreos-assembler/blob/e3905fd2e138de04184c1cd86b99b0fd83cbe5cf/src/create_disk.sh#L17
+bootfs_uuid="96d15588-3596-4b3c-adca-a2ff7279ea63"
+rootfs_uuid="910678ff-f77e-4a7d-8d53-86f2ac47a823"
+
+target=/dev/disk/by-label/${label}
+if ! [ -b "${target}" ]; then
+  echo "$0: Failed to find block device ${target}" 1>&2
+  exit 1
+fi
+
+eval $(blkid -o export ${target})
+case "${label}" in
+  root) orig_uuid="${rootfs_uuid}"; orig_type=xfs ;;
+  boot) orig_uuid="${bootfs_uuid}"; orig_type=ext4 ;;
+  *) echo "unexpected ${label}"; exit 1 ;;
+esac
+
+if [ "${TYPE}" == "${orig_type}" ] && [ "${UUID}" == "${orig_uuid}" ]; then
+  case "${TYPE}" in
+    # For now we need to fsck first, see https://github.com/coreos/coreos-assembler/pull/1452
+    # Basically we're not passing `metadata_csum_seed` as a mkfs.ext4 option
+    # because grub2 barfs on it.
+    ext4) e2fsck -y "${target}" && tune2fs -U random "${target}" ;;
+    xfs) xfs_admin -U generate "${target}" ;;
+    *) echo "unexpected filesystem type ${TYPE}" 1>&2; exit 1 ;;
+  esac
+  echo "Regenerated UUID for ${target}"
+else
+  echo "No changes required for ${target} TYPE=${TYPE} UUID=${UUID}"
+fi

overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/ignition-ostree-uuid-boot.service

@@ -0,0 +1,20 @@
+[Unit]
+Description=Ignition OSTree: Regenerate filesystem UUID (boot)
+DefaultDependencies=false
+ConditionPathExists=/usr/lib/initrd-release
+ConditionKernelCommandLine=ostree
+ConditionPathExists=!/run/ostree-live
+# We run pretty early
+Before=coreos-copy-firstboot-network.service
+Before=ignition-fetch.service
+Before=ignition-setup-base.service
+Before=ignition-setup-user.service
+
+Before=systemd-fsck@dev-disk-by\x2dlabel-boot.service
+Requires=dev-disk-by\x2dlabel-boot.device
+After=dev-disk-by\x2dlabel-boot.device
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/usr/sbin/ignition-ostree-firstboot-uuid boot

overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/ignition-ostree-uuid-root.service

@@ -0,0 +1,22 @@
+[Unit]
+Description=Ignition OSTree: Regenerate filesystem UUID (root)
+# These conditions match mount-firstboot-sysroot.service
+DefaultDependencies=false
+ConditionKernelCommandLine=!root
+ConditionKernelCommandLine=ostree
+ConditionPathExists=!/run/ostree-live
+Before=initrd-root-fs.target
+After=ignition-disks.service
+
+# Avoid racing with fsck
+Before=systemd-fsck@dev-disk-by\x2dlabel-boot.service
+
+# Note we don't have a Requires: /dev/disk/by-label/root here like
+# the -subsequent service does because ignition-disks may have
+# regenerated it.
+Before=ignition-ostree-mount-firstboot-sysroot.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/usr/sbin/ignition-ostree-firstboot-uuid root

overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/module-setup.sh

@@ -33,9 +33,11 @@ install() {
         findmnt   \
         growpart  \
         realpath  \
+        tune2fs   \
         resize2fs \
         tail      \
         touch     \
+        xfs_admin \
         xfs_growfs
 
     # growpart deps
@@ -60,6 +62,11 @@ install() {
     done
 
     install_ignition_unit ignition-ostree-mount-firstboot-sysroot.service diskful
+    for p in boot root; do
+        install_ignition_unit ignition-ostree-uuid-${p}.service diskful
+    done
+    inst_script "$moddir/ignition-ostree-firstboot-uuid" \
+        "/usr/sbin/ignition-ostree-firstboot-uuid"
     install_ignition_unit ignition-ostree-mount-subsequent-sysroot.service diskful-subsequent
     inst_script "$moddir/ignition-ostree-mount-sysroot.sh" \
         "/usr/sbin/ignition-ostree-mount-sysroot"