Fix discovering WWN/serial for devicemapper devices

UDev prefix is DM_ not ID_ for them. On top of that, they don't have
short serials (or at least don't always have).

Change-Id: I5b6075fbff72201a2fd620f789978acceafc417b
(cherry picked from commit 69e22545033f544d628f9c4ecd5a665ba0b5b85e)

3 files changed, 31 insertions, 16 deletions

diff --git a/ironic_python_agent/hardware.py b/ironic_python_agent/hardware.py
index 35faba14..70843f8e 100644
--- a/ironic_python_agent/hardware.py
+++ b/ironic_python_agent/hardware.py
@@ -635,26 +635,34 @@ def list_all_block_devices(block_type='disk',
 
         name = os.path.join('/dev', device['KNAME'])
 
+        extra = {}
         try:
             udev = pyudev.Devices.from_device_file(context, name)
         except pyudev.DeviceNotFoundByFileError as e:
             LOG.warning("Device %(dev)s is inaccessible, skipping... "
                         "Error: %(error)s", {'dev': name, 'error': e})
-            extra = {}
         except pyudev.DeviceNotFoundByNumberError as e:
             LOG.warning("Device %(dev)s is not supported by pyudev, "
                         "skipping... Error: %(error)s",
                         {'dev': name, 'error': e})
-            extra = {}
         else:
             # TODO(lucasagomes): Since lsblk only supports
             # returning the short serial we are using
-            # ID_SERIAL_SHORT here to keep compatibility with the
+            # ID_SERIAL_SHORT first to keep compatibility with the
             # bash deploy ramdisk
-            extra = {key: udev.get('ID_%s' % udev_key) for key, udev_key in
-                     [('wwn', 'WWN'), ('serial', 'SERIAL_SHORT'),
-                      ('wwn_with_extension', 'WWN_WITH_EXTENSION'),
-                      ('wwn_vendor_extension', 'WWN_VENDOR_EXTENSION')]}
+            for key, udev_key in [
+                ('serial', 'SERIAL_SHORT'),
+                ('serial', 'SERIAL'),
+                ('wwn', 'WWN'),
+                ('wwn_with_extension', 'WWN_WITH_EXTENSION'),
+                ('wwn_vendor_extension', 'WWN_VENDOR_EXTENSION')
+            ]:
+                if key in extra:
+                    continue
+                value = (udev.get(f'ID_{udev_key}')
+                         or udev.get(f'DM_{udev_key}'))  # devicemapper
+                if value:
+                    extra[key] = value
 
         # NOTE(lucasagomes): Newer versions of the lsblk tool supports
         # HCTL as a parameter but let's get it from sysfs to avoid breaking
diff --git a/ironic_python_agent/tests/unit/test_hardware.py b/ironic_python_agent/tests/unit/test_hardware.py
index 17d67822..dfe4f872 100644
--- a/ironic_python_agent/tests/unit/test_hardware.py
+++ b/ironic_python_agent/tests/unit/test_hardware.py
@@ -1585,13 +1585,16 @@ class TestGenericHardwareManager(base.IronicAgentTest):
             ('', ''),
         ]
 
-        mocked_mpath.return_value = False
-        mocked_udev.side_effect = iter([
+        mocked_mpath.return_value = True
+        mocked_udev.side_effect = [
             {'ID_WWN': 'wwn%d' % i, 'ID_SERIAL_SHORT': 'serial%d' % i,
+             'ID_SERIAL': 'do not use me',
              'ID_WWN_WITH_EXTENSION': 'wwn-ext%d' % i,
              'ID_WWN_VENDOR_EXTENSION': 'wwn-vendor-ext%d' % i}
-            for i in range(5)
-        ])
+            for i in range(3)
+        ] + [
+            {'DM_WWN': 'wwn3', 'DM_SERIAL': 'serial3'},
+        ]
         mocked_dev_vendor.return_value = 'Super Vendor'
         devices = hardware.list_all_block_devices()
         expected_devices = [
@@ -1625,19 +1628,19 @@ class TestGenericHardwareManager(base.IronicAgentTest):
                                  wwn_vendor_extension='wwn-vendor-ext2',
                                  serial='serial2',
                                  hctl='1:0:0:0'),
-            hardware.BlockDevice(name='/dev/sdd',
+            hardware.BlockDevice(name='/dev/dm-0',
                                  model='NWD-BLP4-1600',
                                  size=1765517033472,
                                  rotational=False,
                                  vendor='Super Vendor',
                                  wwn='wwn3',
-                                 wwn_with_extension='wwn-ext3',
-                                 wwn_vendor_extension='wwn-vendor-ext3',
+                                 wwn_with_extension=None,
+                                 wwn_vendor_extension=None,
                                  serial='serial3',
                                  hctl='1:0:0:0')
         ]
 
-        self.assertEqual(4, len(expected_devices))
+        self.assertEqual(4, len(devices))
         for expected, device in zip(expected_devices, devices):
             # Compare all attrs of the objects
             for attr in ['name', 'model', 'size', 'rotational',
@@ -1646,7 +1649,7 @@ class TestGenericHardwareManager(base.IronicAgentTest):
                 self.assertEqual(getattr(expected, attr),
                                  getattr(device, attr))
         expected_calls = [mock.call('/sys/block/%s/device/scsi_device' % dev)
-                          for dev in ('sda', 'sdb', 'sdc', 'sdd')]
+                          for dev in ('sda', 'sdb', 'sdc', 'dm-0')]
         mocked_listdir.assert_has_calls(expected_calls)
         mocked_mpath.assert_called_once_with()
 
diff --git a/releasenotes/notes/multipath-serial-615fc925984abbf7.yaml b/releasenotes/notes/multipath-serial-615fc925984abbf7.yaml
new file mode 100644
index 00000000..4a13352b
--- /dev/null
+++ b/releasenotes/notes/multipath-serial-615fc925984abbf7.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fixes discovering WWN/serial numbers for devicemapper devices.