fix(config): return a 422 if unsetting a config key that does not exist

    http://www.bennadel.com/blog/2434-http-status-codes-for-invalid-data-400-vs-422.htm is a good explanation of the differences

Author: helgi

rootfs/api/exceptions.py

@@ -18,6 +18,10 @@ class AlreadyExists(APIException):
     status_code = 409
 
 
+class UnprocessableEntity(APIException):
+    status_code = 422
+
+
 class ServiceUnavailable(APIException):
     status_code = 503
     default_detail = 'Service temporarily unavailable, try again later.'

rootfs/api/models/config.py

@@ -3,7 +3,8 @@
 from jsonfield import JSONField
 
 from api.models.release import Release
-from api.models import UuidAuditedModel, DeisException
+from api.models import UuidAuditedModel
+from api.exceptions import DeisException, UnprocessableEntity
 
 
 class Config(UuidAuditedModel):
@@ -130,9 +131,16 @@ def save(self, **kwargs):
                 data = getattr(previous_config, attr, {}).copy()
                 new_data = getattr(self, attr, {}).copy()
 
-                data.update(new_data)
-                # remove config keys if we provided a null value
-                [data.pop(k) for k, v in new_data.items() if v is None]
+                # remove config keys if a null value is provided
+                for key, value in new_data.items():
+                    if value is None:
+                        # error if unsetting non-existing key
+                        if key not in data:
+                            raise UnprocessableEntity('{} does not exist under {}'.format(key, attr))  # noqa
+
+                        data.pop(key)
+                    else:
+                        data[key] = value
                 setattr(self, attr, data)
 
             self.set_healthchecks()

rootfs/api/tests/test_release.py

@@ -333,3 +333,19 @@ def json(self):
                 body = {'version': 2}
                 response = self.client.post(url, body)
                 self.assertEqual(response.status_code, 400, response.data)
+
+    def test_release_unset_config(self, mock_requests):
+        """
+        Test that a release is created when an app is created, a config can be
+        set and then unset without causing a 409 (conflict)
+        """
+        url = '/v2/apps'
+        response = self.client.post(url)
+        self.assertEqual(response.status_code, 201, response.data)
+        app_id = response.data['id']
+
+        # check that updating config rolls a new release
+        url = '/v2/apps/{app_id}/config'.format(**locals())
+        body = {'cpu': json.dumps({'cmd': None})}
+        response = self.client.post(url, body)
+        self.assertEqual(response.status_code, 422, response.data)