Add grub2 element

This patch is adds a new grub2 element that installs the
grub2 bootloader on the image so it can work with Ironic's
local boot support.

This patch also modifies the iso element which was installing
same grub2. It removes the grub2 installation from iso element
and makes it dependent on grub2 element.

Co-Authored-By: Ramakrishnan G <rameshg87@gmail.com>
Change-Id: I37bcf2c525708d1e2e0f95cf5874a279f76861f7

elements/grub2/README.rst

@@ -0,0 +1,7 @@
+=====
+grub2
+=====
+This image installs grub2 bootloader on the image, that's necessary for
+the local boot feature in Ironic to work. This is being made a separated
+element because usually images have grub2 removed for space reasons and
+also because they are going to boot from network (PXE boot).

elements/grub2/package-installs.yaml

@@ -0,0 +1,3 @@
+signed_grub_efi:
+signed_shim_efi:
+grub_bios:

elements/grub2/pkg-map

@@ -0,0 +1,20 @@
+{
+  "family":{
+    "debian":{
+      "signed_grub_efi": "grub-efi-amd64-signed",
+      "signed_shim_efi": "shim-signed",
+      "grub_bios": "grub-pc-bin"
+    },
+    "redhat":{
+      "signed_grub_efi": "efibootmgr grub2-efi-modules grub2-efi",
+      "signed_shim_efi": "shim",
+      "grub_bios": "grub2"
+    }
+  },
+  "default":{
+      "signed_grub_efi": "grub-efi-amd64-signed",
+      "signed_shim_efi": "shim-signed",
+      "grub_bios": "grub-pc-bin"
+  }
+}
+

elements/grub2/post-install.d/01-delete-grubenv

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+
+set -eu
+set -o pipefail
+
+
+# Delete /boot/grub2/grubenv if it exists because
+# it will fail while doing grub-install again.
+rm -f /boot/grub2/grubenv

elements/iso/element-deps

@@ -1 +1,2 @@
+grub2
 package-installs

elements/iso/package-installs.yaml

@@ -1,3 +1 @@
-signed_grub:
-signed_shim:
 syslinux:

elements/iso/pkg-map

@@ -1,19 +1,13 @@
 {
   "family":{
     "debian":{
-      "signed_grub": "grub-efi-amd64-signed",
-      "signed_shim": "shim-signed",
       "syslinux": "syslinux"
     },
     "redhat":{
-      "signed_grub": "grub2-efi",
-      "signed_shim": "shim",
       "syslinux": ""
     }
   },
   "default":{
-      "signed_grub": "grub-efi-amd64-signed",
-      "signed_shim": "shim-signed",
       "syslinux": "syslinux"
   }
 }