Allow reading root_device from instance_info

For the future deployment API we need to be able to set root_device
per deployment in addition to per node. This change adds it.

Change-Id: I1dd046c2e5fca211a84290bac8daa7550b21614f
Story: #2006910
Task: #37955

ironic_python_agent/hardware.py

@@ -952,7 +952,9 @@ class GenericHardwareManager(HardwareManager):
         cached_node = get_cached_node()
         root_device_hints = None
         if cached_node is not None:
-            root_device_hints = cached_node['properties'].get('root_device')
+            root_device_hints = (
+                cached_node['instance_info'].get('root_device')
+                or cached_node['properties'].get('root_device'))
             LOG.debug('Looking for a device matching root hints %s',
                       root_device_hints)
 

ironic_python_agent/tests/unit/test_hardware.py

@@ -1304,7 +1304,8 @@ class TestGenericHardwareManager(base.IronicAgentTest):
     def _get_os_install_device_root_device_hints(self, hints, expected_device,
                                                  mock_cached_node, mock_dev):
         mock_cached_node.return_value = {'properties': {'root_device': hints},
-                                         'uuid': 'node1'}
+                                         'uuid': 'node1',
+                                         'instance_info': {}}
         model = 'fastable sd131 7'
         mock_dev.return_value = [
             hardware.BlockDevice(name='/dev/sda',
@@ -1381,6 +1382,7 @@ class TestGenericHardwareManager(base.IronicAgentTest):
             self, mock_cached_node, mock_dev):
         model = 'fastable sd131 7'
         mock_cached_node.return_value = {
+            'instance_info': {},
             'properties': {
                 'root_device': {
                     'model': model,
@@ -1410,6 +1412,42 @@ class TestGenericHardwareManager(base.IronicAgentTest):
         mock_cached_node.assert_called_once_with()
         mock_dev.assert_called_once_with()
 
+    @mock.patch.object(hardware, 'list_all_block_devices', autospec=True)
+    @mock.patch.object(hardware, 'get_cached_node', autospec=True)
+    def test_get_os_install_device_root_device_hints_iinfo(self,
+                                                           mock_cached_node,
+                                                           mock_dev):
+        model = 'fastable sd131 7'
+        mock_cached_node.return_value = {
+            'instance_info': {'root_device': {'model': model}},
+            'uuid': 'node1'
+        }
+        mock_dev.return_value = [
+            hardware.BlockDevice(name='/dev/sda',
+                                 model='TinyUSB Drive',
+                                 size=3116853504,
+                                 rotational=False,
+                                 vendor='Super Vendor',
+                                 wwn='wwn0',
+                                 wwn_with_extension='wwn0ven0',
+                                 wwn_vendor_extension='ven0',
+                                 serial='serial0'),
+            hardware.BlockDevice(name='/dev/sdb',
+                                 model=model,
+                                 size=10737418240,
+                                 rotational=True,
+                                 vendor='fake-vendor',
+                                 wwn='fake-wwn',
+                                 wwn_with_extension='fake-wwnven0',
+                                 wwn_vendor_extension='ven0',
+                                 serial='fake-serial',
+                                 by_path='/dev/disk/by-path/1:0:0:0'),
+        ]
+
+        self.assertEqual('/dev/sdb', self.hardware.get_os_install_device())
+        mock_cached_node.assert_called_once_with()
+        mock_dev.assert_called_once_with()
+
     def test__get_device_info(self):
         fileobj = mock.mock_open(read_data='fake-vendor')
         with mock.patch(

releasenotes/notes/instance-info-root-device-02fed0966bb00fb3.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Allows reading the ``root_device`` from ``instance_info``, overriding
+    the value in ``properties``.