Return false for MBR bootloader check on UEFI machines

Somewhat common are dual boot images that have both a MBR loader
and the contents required for a UEFI boot, as largely the pointer
to where to begin reading the rest of the boot loader occurs in
the first few hundred bytes on disk which redirects the disk to
begin reading from a known address.

This goes sideways on UEFI machines where this method of booting
is not recognized nor supported. Thus we need to return false when
we encounter this state.

Change-Id: I8c0b42bb71b9e26ed7fec8894e21ce7fc06b94a1
Story: 2007455
Task: 39133
(cherry picked from commit 81137d4045)

ironic_python_agent/extensions/image.py

@@ -167,6 +167,14 @@ def _is_bootloader_loaded(dev):
                 return True
         return False
 
+    boot = hardware.dispatch_to_managers('get_boot_info')
+
+    if boot.current_boot_mode != 'bios':
+        # We're in UEFI mode, this logic is invalid
+        LOG.debug('Skipping boot sector check as the system is in UEFI '
+                  'boot mode.')
+        return False
+
     try:
         # Looking for things marked "bootable" in the partition table
         stdout, stderr = utils.execute('parted', dev, '-s', '-m',

ironic_python_agent/tests/unit/extensions/test_image.py

@@ -711,6 +711,8 @@ efibootmgr: ** Warning ** : Boot0005 has same label ironic1\n
 
     def test__is_bootloader_loaded(self, mock_execute,
                                    mock_dispatch):
+        mock_dispatch.return_value = hardware.BootInfo(
+            current_boot_mode='bios')
         parted_output = ('BYT;\n'
                          '/dev/loop1:46.1MB:loopback:512:512:gpt:Loopback '
                          'device:;\n'
@@ -765,6 +767,16 @@ efibootmgr: ** Warning ** : Boot0005 has same label ironic1\n
         result = image._is_bootloader_loaded(self.fake_dev)
         self.assertFalse(result)
 
+    def test__is_bootloader_loaded_uefi_mode(self, mock_execute,
+                                             mock_dispatch):
+
+        mock_dispatch.return_value = hardware.BootInfo(
+            current_boot_mode='uefi')
+        result = image._is_bootloader_loaded(self.fake_dev)
+        self.assertFalse(result)
+        mock_dispatch.assert_any_call('get_boot_info')
+        self.assertEqual(0, mock_execute.call_count)
+
     @mock.patch.object(image, '_get_partition', autospec=True)
     @mock.patch.object(utils, 'get_efi_part_on_device', autospec=True)
     def test__manage_uefi_no_partition(self, mock_utils_efi_part,

releasenotes/notes/bootloader-ignored-uefi-mode-8578a009d5b5be62.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes an issue with deployment ramdisks running in UEFI boot mode where
+    dual-boot images may cause the logic to prematurely exit before UEFI
+    parameters can be updated. Internal checks for a BIOS bootloader will
+    always return ``False`` now when the machine is in UEFI mode.