Avoid cpu_arch None values in iscsi deployments

Ironic will fail iscsi deployments if cpu_arch is not specified.
We need to make cpu_arch optional to prevent that.

Change-Id: I184dc53d664dd8631604f98e34786fa06d04d1ed
Task: 28123
Story: 2004448

ironic/drivers/modules/iscsi_deploy.py

@@ -117,8 +117,11 @@ def get_deploy_info(node, address, iqn, port=None, lun='1', conv_flags=None):
                        'ephemeral_mb': i_info['ephemeral_mb'],
                        'preserve_ephemeral': i_info['preserve_ephemeral'],
                        'boot_option': deploy_utils.get_boot_option(node),
-                       'boot_mode': boot_mode_utils.get_boot_mode(node),
-                       'cpu_arch': node.properties.get('cpu_arch')})
+                       'boot_mode': boot_mode_utils.get_boot_mode(node)})
+
+        cpu_arch = node.properties.get('cpu_arch')
+        if cpu_arch is not None:
+            params['cpu_arch'] = cpu_arch
 
         # Append disk label if specified
         disk_label = deploy_utils.get_disk_label(node)

ironic/tests/unit/drivers/modules/test_iscsi_deploy.py

@@ -418,6 +418,15 @@ class IscsiDeployMethodsTestCase(db_base.DbTestCase):
         ret_val = self._test_get_deploy_info(extra_instance_info=capabilities)
         self.assertEqual('local', ret_val['boot_option'])
 
+    def test_get_deploy_info_cpu_arch(self):
+        ret_val = self._test_get_deploy_info()
+        self.assertEqual('x86_64', ret_val['cpu_arch'])
+
+    def test_get_deploy_info_cpu_arch_none(self):
+        self.node.properties['cpu_arch'] = None
+        ret_val = self._test_get_deploy_info()
+        self.assertNotIn('cpu_arch', ret_val)
+
     def test_get_deploy_info_disk_label(self):
         capabilities = {'capabilities': {'disk_label': 'msdos'}}
         ret_val = self._test_get_deploy_info(extra_instance_info=capabilities)

releasenotes/notes/iscsi-optional-cpu-arch-ebf6a90dde34172c.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue where iSCSI based deployments fail if the ``cpu_arch``
+    property is not specified on a node.
+