Provide a clear error message when trying to access ironic (not inspector)

Apparently, it's a common enough case, especially with standalone ironic.

Change-Id: Ic0ffa49aeb2f13cfd08b6027f3b61f2fcc750b4d

ironic_inspector_client/common/http.py

@@ -47,12 +47,31 @@ class ClientError(requests.HTTPError):
         # inspector returns error message in body
         msg = response.content.decode(_ERROR_ENCODING)
         try:
-            msg = json.loads(msg)['error']['message']
+            msg = json.loads(msg)
         except ValueError:
             LOG.debug('Old style error response returned, assuming '
                       'ironic-discoverd')
-        except (KeyError, TypeError):
+        except TypeError:
             LOG.exception('Bad error response from Ironic Inspector')
+        else:
+            try:
+                msg = msg['error']['message']
+            except KeyError as exc:
+                LOG.error('Invalid error response from Ironic Inspector: '
+                          '%(msg)s (missing key %(key)s)',
+                          {'msg': msg, 'key': exc})
+                # It's surprisingly common to try accessing ironic URL with
+                # ironic-inspector-client, handle this case
+                try:
+                    msg = msg['error_message']
+                except KeyError:
+                    pass
+                else:
+                    msg = _('Received Ironic-style response %s. Are you '
+                            'trying to access Ironic URL instead of Ironic '
+                            'Inspector?') % msg
+            except TypeError:
+                LOG.exception('Bad error response from Ironic Inspector')
 
         LOG.debug('Inspector returned error "%(msg)s" (HTTP %(code)s)',
                   {'msg': msg, 'code': response.status_code})

ironic_inspector_client/test/test_common_http.py

@@ -192,3 +192,28 @@ class TestRequest(unittest.TestCase):
 
         self.assertRaisesRegex(http.ClientError, 'boom',
                                self.get_client().request, 'get', 'url')
+
+    def test_accessing_ironic(self):
+        self.req.return_value.status_code = 400
+        self.req.return_value.content = json.dumps(
+            {"error_message": "{\"code\": 404, \"title\": \"Not Found\", "
+             "\"description\": \"\"}"}).encode('utf-8')
+
+        self.assertRaisesRegex(http.ClientError,
+                               'Ironic-style response.*Not Found',
+                               self.get_client().request, 'get', 'url')
+
+    def test_error_non_sense(self):
+        self.req.return_value.status_code = 400
+        self.req.return_value.content = json.dumps(
+            {'hello': 'world'}).encode('utf-8')
+
+        self.assertRaisesRegex(http.ClientError, 'hello',
+                               self.get_client().request, 'get', 'url')
+
+    def test_error_non_sense2(self):
+        self.req.return_value.status_code = 400
+        self.req.return_value.content = b'42'
+
+        self.assertRaisesRegex(http.ClientError, '42',
+                               self.get_client().request, 'get', 'url')

releasenotes/notes/ironic-error-657d352b31ba77ed.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Provides a clear error message when trying to access an ironic URL with
+    ironic-inspector-client.