Move grub-install to the end, and skip for partition images

The bootloader element installs the grub bootloader for whole-disk
images, but it also correctly sets values in /etc/default/grub and BLS
entries.

This value setting is useful even if the bootloader isn't installed.
For example, the overcloud-full partition image benefits from a
correct /etc/default/grub and BLS entries which ironic-python-agent
will use when it installs grub on the disk during baremetal deploy.

This change moves the actual grub install to the end of the script,
and if there is no $DIB_BLOCK_DEVICE set then install is skipped.

This allows overcloud-full to use the bootloader element instead of
the grub2 element, so the correct grub defaults are set on centos9,
including the correct root device on centos9.

Change-Id: I8cb34914bbbfa05521bbb71cc6637368b980358f

diskimage_builder/elements/bootloader/finalise.d/50-bootloader

@@ -25,6 +25,8 @@ BOOT_DEV=$IMAGE_BLOCK_DEVICE
 declare -A DEVICES
 eval DEVICES=( $IMAGE_BLOCK_DEVICES )
 
+DIB_BLOCK_DEVICE=${DIB_BLOCK_DEVICE:-}
+
 # Right now we can't use pkg-map to branch by arch, so tag an
 # architecture specific virtual package so we can install the
 # rigth thing based on distribution.
@@ -36,9 +38,7 @@ elif [[ "${DIB_BLOCK_DEVICE}" == "mbr" ||
 elif [[ "${DIB_BLOCK_DEVICE}" == "efi" ]]; then
     install-packages -m bootloader grub-efi grub-efi-$ARCH
 else
-    echo "Failure: I'm not sure what bootloader to install"
+    install-packages -m bootloader grub-pc grub-efi grub-efi-$ARCH
-    echo "Ensure you have included a block-device-* element"
-    exit 1
 fi
 
 GRUBNAME=$(type -p grub-install) || echo "trying grub2-install"
@@ -70,8 +70,6 @@ else
     GRUBENV=/boot/grub/grubenv
 fi
 
-echo "Installing GRUB2..."
-
 # When using EFI image-based builds, particularly rhel element
 # based on RHEL>=8.2 .qcow2, we might have /boot/grub2/grubenv
 # as a dangling symlink to /boot/efi because we have extracted
@@ -83,55 +81,6 @@ if [[ -L $GRUBENV ]]; then
     rm -f $GRUBENV
 fi
 
-# We need --force so grub does not fail due to being installed on the
-# root partition of a block device.
-GRUB_OPTS="--force "
-
-if [[ "$ARCH" =~ "ppc" ]] ; then
-    # For PPC (64-Bit regardless of Endian-ness), we use the "boot"
-    # partition as the one to point grub-install to, not the loopback
-    # device.  ppc has a dedicated PReP boot partition.
-    # For grub2 < 2.02~beta3 this needs to be a /dev/mapper/... node after
-    # that a dev/loopXpN node will work fine.
-    $GRUBNAME --modules="part_msdos" $GRUB_OPTS ${DEVICES[boot]} --no-nvram
-else
-    # This set of modules is sufficient for all installs (mbr/gpt/efi)
-    modules="part_msdos part_gpt lvm"
-
-    if [[ ${DIB_BLOCK_DEVICE} == "mbr" || ${DIB_BLOCK_DEVICE} == "gpt" ]]; then
-        if [[ ! "x86_64 amd64" =~ ${ARCH} ]]; then
-            echo "*** ${ARCH} is not supported by mbr/gpt"
-        fi
-        $GRUBNAME --modules="$modules biosdisk" --target=i386-pc \
-                $GRUB_OPTS $BOOT_DEV
-    elif [[ ${DIB_BLOCK_DEVICE} == "efi" ]]; then
-        # We need to manually set the target if it's different to
-        # the host.  Setup for EFI
-        case $ARCH in
-            "x86_64"|"amd64")
-                # This call installs grub for BIOS compatability
-                # which makes portable EFI/BIOS images.
-                $GRUBNAME --modules="$modules" --target=i386-pc $BOOT_DEV
-                # Set the x86_64 specific efi target for the generic
-                # installation below.
-                GRUB_OPTS="--target=x86_64-efi"
-                ;;
-            # At this point, we don't need to override the target
-            # for any other architectures.
-        esac
-        # If we don't have a distro specific dir with presigned efi targets
-        # we install a generic one.
-        if [ ! -d /boot/efi/$EFI_BOOT_DIR ]; then
-            echo "WARNING: /boot/efi/$EFI_BOOT_DIR does not exist, UEFI secure boot not supported"
-            # This tells the EFI install to put the EFI binaries into
-            # the generic /BOOT directory and avoids trying to update
-            # nvram settings.
-            extra_options="--removable"
-            $GRUBNAME --modules="$modules" $extra_options $GRUB_OPTS $BOOT_DEV
-        fi
-    fi
-fi
-
 echo "GRUB_DEVICE=LABEL=${DIB_ROOT_LABEL}" >> /etc/default/grub
 echo 'GRUB_DISABLE_LINUX_UUID=true' >> /etc/default/grub
 echo "GRUB_TIMEOUT=${DIB_GRUB_TIMEOUT:-5}" >>/etc/default/grub
@@ -206,3 +155,59 @@ if [[ ${DIB_BLOCK_DEVICE} == "efi" ]]; then
     fi
 fi
 
+if [[ ! "$ARCH" =~ "ppc" ]] && [[ -z  "${DIB_BLOCK_DEVICE}" ]]; then
+    echo "WARNING: No bootloader installation will occur."
+    echo "To install a bootloader ensure you have included a block-device-* element"
+    exit 0
+fi
+
+echo "Installing GRUB2..."
+
+# We need --force so grub does not fail due to being installed on the
+# root partition of a block device.
+GRUB_OPTS="--force "
+
+if [[ "$ARCH" =~ "ppc" ]] ; then
+    # For PPC (64-Bit regardless of Endian-ness), we use the "boot"
+    # partition as the one to point grub-install to, not the loopback
+    # device.  ppc has a dedicated PReP boot partition.
+    # For grub2 < 2.02~beta3 this needs to be a /dev/mapper/... node after
+    # that a dev/loopXpN node will work fine.
+    $GRUBNAME --modules="part_msdos" $GRUB_OPTS ${DEVICES[boot]} --no-nvram
+else
+    # This set of modules is sufficient for all installs (mbr/gpt/efi)
+    modules="part_msdos part_gpt lvm"
+
+    if [[ ${DIB_BLOCK_DEVICE} == "mbr" || ${DIB_BLOCK_DEVICE} == "gpt" ]]; then
+        if [[ ! "x86_64 amd64" =~ ${ARCH} ]]; then
+            echo "*** ${ARCH} is not supported by mbr/gpt"
+        fi
+        $GRUBNAME --modules="$modules biosdisk" --target=i386-pc \
+                $GRUB_OPTS $BOOT_DEV
+    elif [[ ${DIB_BLOCK_DEVICE} == "efi" ]]; then
+        # We need to manually set the target if it's different to
+        # the host.  Setup for EFI
+        case $ARCH in
+            "x86_64"|"amd64")
+                # This call installs grub for BIOS compatability
+                # which makes portable EFI/BIOS images.
+                $GRUBNAME --modules="$modules" --target=i386-pc $BOOT_DEV
+                # Set the x86_64 specific efi target for the generic
+                # installation below.
+                GRUB_OPTS="--target=x86_64-efi"
+                ;;
+            # At this point, we don't need to override the target
+            # for any other architectures.
+        esac
+        # If we don't have a distro specific dir with presigned efi targets
+        # we install a generic one.
+        if [ ! -d /boot/efi/$EFI_BOOT_DIR ]; then
+            echo "WARNING: /boot/efi/$EFI_BOOT_DIR does not exist, UEFI secure boot not supported"
+            # This tells the EFI install to put the EFI binaries into
+            # the generic /BOOT directory and avoids trying to update
+            # nvram settings.
+            extra_options="--removable"
+            $GRUBNAME --modules="$modules" $extra_options $GRUB_OPTS $BOOT_DEV
+        fi
+    fi
+fi