Fix regression on API < 1.25

Signed-off-by: Viktor Adam <rycus86@gmail.com>

docker/api/service.py

@@ -137,6 +137,8 @@ class ServiceApiMixin(object):
         auth_header = auth.get_config_header(self, registry)
         if auth_header:
             headers['X-Registry-Auth'] = auth_header
+        if utils.version_lt(self._version, '1.25'):
+            networks = networks or task_template.pop('Networks', None)
         data = {
             'Name': name,
             'Labels': labels,
@@ -411,7 +413,12 @@ class ServiceApiMixin(object):
 
         if networks is not None:
             converted_networks = utils.convert_service_networks(networks)
-            data['TaskTemplate']['Networks'] = converted_networks
+            if utils.version_lt(self._version, '1.25'):
+                data['Networks'] = converted_networks
+            else:
+                data['TaskTemplate']['Networks'] = converted_networks
+        elif utils.version_lt(self._version, '1.25'):
+            data['Networks'] = current.get('Networks')
         elif data['TaskTemplate'].get('Networks') is None:
             current_task_template = current.get('TaskTemplate', {})
             current_networks = current_task_template.get('Networks')

tests/integration/models_services_test.py

@@ -179,6 +179,30 @@ class ServiceTest(unittest.TestCase):
         service.reload()
         assert not service.attrs['Spec'].get('Labels')
 
+    def test_update_retains_networks(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        network_name = helpers.random_name()
+        network = client.networks.create(
+            network_name, driver='overlay'
+        )
+        service = client.services.create(
+            # create arguments
+            name=helpers.random_name(),
+            networks=[network.id],
+            # ContainerSpec arguments
+            image="alpine",
+            command="sleep 300"
+        )
+        service.update(
+            # create argument
+            name=service.name,
+            # ContainerSpec argument
+            command="sleep 600"
+        )
+        service.reload()
+        networks = service.attrs['Spec']['TaskTemplate']['Networks']
+        assert networks == [{'Target': network.id}]
+
     def test_scale_service(self):
         client = docker.from_env(version=TEST_API_VERSION)
         service = client.services.create(