Merge lp:~blake-rouse/maas-images/fix-centos-efi into lp:maas-images

[Blake Rouse]

Fix boot loader ordering for CentOS 7 UEFI.

Previously when deploying CentOS 7 the 'centos' efi loader would become the first loader in the boot order, which prevents re-deployments of any OS as the machine will no longer boot from the network first. This branch updates the boot order for EFI and places the currently booted entry as the first in the boot order. Since this is run in ephemeral mode this ensures that the NIC that the machine booted from will start first. 'centos' entry will be after the network, so if MAAS is down the machine will still boot from 'centos' if MAAS is down and the machine reboots. Previous \EFI entries are also removed from bios as those no longer exists as curtin creates a new \EFI partition on deployment.

[Andres Rodriguez (andreserl)]

lgtm!

review: Approve

=== modified file 'curtin/centos7/curtin-hooks.py'
--- curtin/centos7/curtin-hooks.py	2017-04-25 01:26:36 +0000
+++ curtin/centos7/curtin-hooks.py	2017-05-04 03:03:00 +0000
@@ -143,13 +143,53 @@
         in_chroot(['grub2-mkconfig', '-o', '/boot/grub2/grub.cfg'])
 
 
-def install_uefi(target):
-    """Install the EFI data from /boot into efi partition."""
+def get_efibootmgr_value(output, key):
+    """Parses the `output` from 'efibootmgr' to return value for `key`."""
+    for line in output.splitlines():
+        split = line.split(':')
+        if len(split) == 2:
+            curr_key = split[0].strip()
+            value = split[1].strip()
+            if curr_key == key:
+                return value
+
+
+def get_file_efi_loaders(output):
+    """Parses the `output` from 'efibootmgr' to return all loaders that exist
+    in '\EFI' path."""
+    return re.findall(
+        r"^Boot(?P<hex>[0-9a-fA-F]{4})\*?\s*\S+\s+.*File\(\\EFI.*$",
+        output, re.MULTILINE)
+
+
+def grub2_install_efi(target):
+    """Configure for EFI.
+
+    First capture the currently booted loader (normally a network device),
+    then perform grub installation (adds a new bootloader and adjusts the
+    boot order), finally re-adjust the boot order so that the currently booted
+    loader is set to boot first in the new order.
+    """
     with util.RunInChroot(target) as in_chroot:
+        stdout, _ = in_chroot(['efibootmgr', '-v'], capture=True)
+        currently_booted = get_efibootmgr_value(stdout, 'BootCurrent')
+        loaders = get_file_efi_loaders(stdout)
+        if currently_booted in loaders:
+            loaders.remove(currently_booted)
+        for loader in loaders:
+            in_chroot(['efibootmgr', '-B', '-b', loader], capture=True)
         in_chroot([
             'grub2-install', '--target=x86_64-efi',
             '--efi-directory', '/boot/efi',
             '--recheck'])
+        stdout, _ = in_chroot(['efibootmgr'], capture=True)
+        currently_booted = get_efibootmgr_value(stdout, 'BootCurrent')
+        boot_order = get_efibootmgr_value(stdout, 'BootOrder').split(',')
+        if currently_booted in boot_order:
+            boot_order.remove(currently_booted)
+        boot_order = [currently_booted] + boot_order
+        new_boot_order = ','.join(boot_order)
+        in_chroot(['efibootmgr', '-o', new_boot_order])
 
 
 def set_autorelabel(target):
@@ -283,7 +323,7 @@
         target, extra=get_extra_kernel_parameters())
     grub2_mkconfig(target)
     if util.is_uefi_bootable():
-        install_uefi(target)
+        grub2_install_efi(target)
     else:
         for dev in devices:
             grub2_install(target, dev)