If -x-networking is used, set the correct API version.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

compose/cli/command.py

@@ -67,8 +67,8 @@ def get_config_path(file_option):
     return [config_file] if config_file else None
 
 
-def get_client(verbose=False):
-    client = docker_client()
+def get_client(verbose=False, version=None):
+    client = docker_client(version=version)
     if verbose:
         version_info = six.iteritems(client.version())
         log.info("Compose version %s", __version__)
@@ -83,11 +83,12 @@ def get_project(base_dir, config_path=None, project_name=None, verbose=False,
                 use_networking=False, network_driver=None):
     config_details = config.find(base_dir, config_path)
 
+    api_version = '1.21' if use_networking else None
     try:
         return Project.from_dicts(
             get_project_name(config_details.working_dir, project_name),
             config.load(config_details),
-            get_client(verbose=verbose),
+            get_client(verbose=verbose, version=api_version),
             use_networking=use_networking,
             network_driver=network_driver,
         )

compose/cli/docker_client.py

@@ -9,7 +9,10 @@ from ..const import HTTP_TIMEOUT
 log = logging.getLogger(__name__)
 
 
-def docker_client():
+DEFAULT_API_VERSION = '1.19'
+
+
+def docker_client(version=None):
     """
     Returns a docker-py client configured using environment variables
     according to the same logic as the official Docker client.
@@ -18,6 +21,8 @@ def docker_client():
         log.warn('The DOCKER_CLIENT_TIMEOUT environment variable is deprecated. Please use COMPOSE_HTTP_TIMEOUT instead.')
 
     kwargs = kwargs_from_env(assert_hostname=False)
-    kwargs['version'] = os.environ.get('COMPOSE_API_VERSION', '1.19')
+    kwargs['version'] = version or os.environ.get(
+        'COMPOSE_API_VERSION',
+        DEFAULT_API_VERSION)
     kwargs['timeout'] = HTTP_TIMEOUT
     return Client(**kwargs)