Properly report preprocessing errors to a user

Currently we only return "Data pre-processing failed" and the only option
to figure out what went wrong is to dive into logs.

Also fixed error message for unexpected exceptions during pre-processing
to actually contain some exception information.

Change-Id: I998c0bbd48cc57b7b13fac220f4f7cfe2a5e0681
Closes-Bug: #1523907

ironic_inspector/process.py

@@ -81,8 +81,11 @@ def process(introspection_data):
             LOG.exception(_LE('Hook %(hook)s failed, delaying error report '
                               'until node look up: %(error)s'),
                           {'hook': hook_ext.name, 'error': exc})
-            failures.append(_('Unexpected exception during preprocessing '
-                              'in hook %s') % hook_ext.name)
+            failures.append(_('Unexpected exception %(exc_class)s during '
+                              'preprocessing in hook %(hook)s: %(error)s') %
+                            {'hook': hook_ext.name,
+                             'exc_class': exc.__class__.__name__,
+                             'error': exc})
 
     node_info = _find_node_info(introspection_data, failures)
     if node_info:
@@ -96,7 +99,7 @@ def process(introspection_data):
             'uuid': node_info.uuid,
             'failures': '\n'.join(failures)
         }
-        node_info.finished(error=_('Data pre-processing failed'))
+        node_info.finished(error='\n'.join(failures))
         raise utils.Error(msg)
     elif not node_info:
         msg = _('The following failures happened during running '
@@ -119,8 +122,10 @@ def process(introspection_data):
         node_info.finished(error=str(exc))
         raise
     except Exception as exc:
-        msg = _('Unexpected exception during processing')
-        LOG.exception(msg)
+        LOG.exception(_LE('Unexpected exception during processing'))
+        msg = _('Unexpected exception %(exc_class)s during processing: '
+                '%(error)s') % {'exc_class': exc.__class__.__name__,
+                                'error': exc}
         node_info.finished(error=msg)
         raise utils.Error(msg)
 

ironic_inspector/test/test_process.py

@@ -144,7 +144,7 @@ class TestProcess(BaseTest):
                                 process.process, self.data)
 
         pop_mock.return_value.finished.assert_called_once_with(
-            error='Unexpected exception during processing')
+            error='Unexpected exception RuntimeError during processing: boom')
 
     @prepare_mocks
     def test_hook_unexpected_exceptions(self, cli, pop_mock, process_mock):
@@ -158,7 +158,10 @@ class TestProcess(BaseTest):
                                 process.process, self.data)
 
         pop_mock.return_value.finished.assert_called_once_with(
-            error='Data pre-processing failed')
+            error=mock.ANY)
+        error_message = pop_mock.return_value.finished.call_args[1]['error']
+        self.assertIn('RuntimeError', error_message)
+        self.assertIn('boom', error_message)
 
     @prepare_mocks
     def test_hook_unexpected_exceptions_no_node(self, cli, pop_mock,

releasenotes/notes/preprocessing-error-01e55b4db20fb7fc.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fixed confusing error message shown to user when something bad happens
+    during preprocessing (https://launchpad.net/bugs/1523907).