Finish labels implementation, add tests and docs

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

docker/utils/utils.py

@@ -454,14 +454,13 @@ def create_container_config(
             for k, v in six.iteritems(environment)
         ]
 
-    if isinstance(labels, six.string_types):
-        labels = [labels, ]
+    if labels is not None and compare_version('1.18', version) < 0:
+        raise errors.DockerException(
+            'labels were only introduced in API version 1.18'
+        )
 
     if isinstance(labels, list):
-        labels_dict = {}
-        for lbl in labels:
-            labels_dict[lbl] = {}
-        labels = labels_dict
+        labels = dict((lbl, six.text_type('')) for lbl in labels)
 
     if isinstance(mem_limit, six.string_types):
         mem_limit = parse_bytes(mem_limit)

docs/api.md

@@ -209,6 +209,7 @@ from. Optionally a single string joining container id's with commas
 * memswap_limit (int):
 * host_config (dict): A [HostConfig](hostconfig.md) dictionary
 * mac_address (str): The Mac Address to assign the container
+* labels (dict or list): A dictionary of name-value labels (e.g. `{"label1": "value1", "label2": "value2"}`) or a list of names of labels to set with empty values (e.g. `["label1", "label2"]`)
 
 **Returns** (dict): A dictionary with an image 'Id' key and a 'Warnings' key.
 

tests/test.py

@@ -1305,6 +1305,54 @@ class DockerClientTest(Cleanup, unittest.TestCase):
             args[1]['timeout'], docker.client.DEFAULT_TIMEOUT_SECONDS
         )
 
+    def test_create_container_with_labels_dict(self):
+        labels_dict = {
+            six.text_type('foo'): six.text_type('1'),
+            six.text_type('bar'): six.text_type('2'),
+        }
+        try:
+            self.client.create_container(
+                'busybox', 'true',
+                labels=labels_dict,
+            )
+        except Exception as e:
+            self.fail('Command should not raise exception: {0}'.format(e))
+        args = fake_request.call_args
+        self.assertEqual(args[0][0], url_prefix + 'containers/create')
+        self.assertEqual(json.loads(args[1]['data'])['Labels'], labels_dict)
+        self.assertEqual(
+            args[1]['headers'], {'Content-Type': 'application/json'}
+        )
+        self.assertEqual(
+            args[1]['timeout'], docker.client.DEFAULT_TIMEOUT_SECONDS
+        )
+
+    def test_create_container_with_labels_list(self):
+        labels_list = [
+            six.text_type('foo'),
+            six.text_type('bar'),
+        ]
+        labels_dict = {
+            six.text_type('foo'): six.text_type(),
+            six.text_type('bar'): six.text_type(),
+        }
+        try:
+            self.client.create_container(
+                'busybox', 'true',
+                labels=labels_list,
+            )
+        except Exception as e:
+            self.fail('Command should not raise exception: {0}'.format(e))
+        args = fake_request.call_args
+        self.assertEqual(args[0][0], url_prefix + 'containers/create')
+        self.assertEqual(json.loads(args[1]['data'])['Labels'], labels_dict)
+        self.assertEqual(
+            args[1]['headers'], {'Content-Type': 'application/json'}
+        )
+        self.assertEqual(
+            args[1]['timeout'], docker.client.DEFAULT_TIMEOUT_SECONDS
+        )
+
     def test_resize_container(self):
         try:
             self.client.resize(