external volume disallows other config keys

Signed-off-by: Joffrey F <joffrey@docker.com>

compose/config/fields_schema_v2.json

@@ -32,6 +32,7 @@
   "definitions": {
     "volume": {
       "id": "#/definitions/volume",
+      "oneOf": [{
         "type": "object",
         "properties": {
           "driver": {"type": "string"},
@@ -41,7 +42,12 @@
               "^.+$": {"type": ["string", "number"]}
             },
             "additionalProperties": false
+          }
         },
+        "additionalProperties": false
+      }, {
+        "type": "object",
+        "properties": {
           "external": {
             "type": ["boolean", "object"],
             "properties": {
@@ -49,7 +55,9 @@
             },
             "additionalProperties": false
           }
-      }
+        },
+        "additionalProperties": false
+      }]
     }
   },
   "additionalProperties": false

tests/unit/config/config_test.py

@@ -793,6 +793,19 @@ class ConfigTest(unittest.TestCase):
         assert 'ext2' in volumes
         assert volumes['ext2']['external']['name'] == 'aliased'
 
+    def test_external_volume_invalid_config(self):
+        config_details = build_config_details({
+            'version': 2,
+            'services': {
+                'bogus': {'image': 'busybox'}
+            },
+            'volumes': {
+                'ext': {'external': True, 'driver': 'foo'}
+            }
+        })
+        with self.assertRaises(ConfigurationError):
+            config.load(config_details)
+
 
 class PortsTest(unittest.TestCase):
     INVALID_PORTS_TYPES = [