Try to set boot device to PXE before rebooting

Change-Id: I4c50048f6ceac609315a08282a50c3ca61568d8f
Closes-Bug: #1401801

ironic_discoverd/discover.py

@@ -101,6 +101,13 @@ def _background_start_discover(ironic, node):
         firewall.update_filters(ironic)
 
     if not node.extra.get('ipmi_setup_credentials'):
+        try:
+            utils.retry_on_conflict(ironic.node.set_boot_device,
+                                    node.uuid, 'pxe', persistent=False)
+        except Exception as exc:
+            LOG.warning('Failed to set boot device to PXE for node %s: %s',
+                        node.uuid, exc)
+
         try:
             utils.retry_on_conflict(ironic.node.set_power_state,
                                     node.uuid, 'reboot')

ironic_discoverd/test/test_discover.py

@@ -76,6 +76,12 @@ class TestDiscover(test_base.BaseTest):
             exceptions.Conflict(),  # this is just retried
             exceptions.InternalServerError(),
             None]
+        # Failure to set boot device is also not fatal
+        cli.node.set_boot_device.side_effect = [
+            exceptions.Conflict(),  # this is just retried
+            None,
+            exceptions.InternalServerError(),
+            None]
 
         discover.discover(['uuid1', 'uuid2', 'uuid3'])
 
@@ -96,6 +102,7 @@ class TestDiscover(test_base.BaseTest):
                                  mac=[])
         filters_mock.assert_called_with(cli)
         self.assertEqual(2, filters_mock.call_count)  # 1 node w/o ports
+        self.assertEqual(4, cli.node.set_boot_device.call_count)
         self.assertEqual(4, cli.node.set_power_state.call_count)
         cli.node.set_power_state.assert_called_with(mock.ANY, 'reboot')
         patch = [{'op': 'add', 'path': '/extra/on_discovery', 'value': 'true'},