Don't add long path prefix to build context URLs

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

compose/config/__init__.py

@@ -6,6 +6,7 @@ from . import environment
 from .config import ConfigurationError
 from .config import DOCKER_CONFIG_KEYS
 from .config import find
+from .config import is_url
 from .config import load
 from .config import merge_environment
 from .config import merge_labels

compose/service.py

@@ -27,6 +27,7 @@ from . import __version__
 from . import const
 from . import progress_stream
 from .config import DOCKER_CONFIG_KEYS
+from .config import is_url
 from .config import merge_environment
 from .config import merge_labels
 from .config.errors import DependencyError
@@ -1676,7 +1677,7 @@ def rewrite_build_path(path):
     if not six.PY3 and not IS_WINDOWS_PLATFORM:
         path = path.encode('utf8')
 
-    if IS_WINDOWS_PLATFORM and not path.startswith(WINDOWS_LONGPATH_PREFIX):
+    if IS_WINDOWS_PLATFORM and not is_url(path) and not path.startswith(WINDOWS_LONGPATH_PREFIX):
         path = WINDOWS_LONGPATH_PREFIX + os.path.normpath(path)
 
     return path

tests/unit/service_test.py

@@ -21,6 +21,7 @@ from compose.const import LABEL_ONE_OFF
 from compose.const import LABEL_PROJECT
 from compose.const import LABEL_SERVICE
 from compose.const import SECRETS_PATH
+from compose.const import WINDOWS_LONGPATH_PREFIX
 from compose.container import Container
 from compose.errors import OperationFailedError
 from compose.parallel import ParallelStreamWriter
@@ -38,6 +39,7 @@ from compose.service import NeedsBuildError
 from compose.service import NetworkMode
 from compose.service import NoSuchImageError
 from compose.service import parse_repository_tag
+from compose.service import rewrite_build_path
 from compose.service import Service
 from compose.service import ServiceNetworkMode
 from compose.service import warn_on_masked_volume
@@ -1486,3 +1488,28 @@ class ServiceSecretTest(unittest.TestCase):
 
         assert volumes[0].source == secret1['file']
         assert volumes[0].target == '{}/{}'.format(SECRETS_PATH, secret1['secret'].source)
+
+
+class RewriteBuildPathTest(unittest.TestCase):
+    @mock.patch('compose.service.IS_WINDOWS_PLATFORM', True)
+    def test_rewrite_url_no_prefix(self):
+        urls = [
+            'http://test.com',
+            'https://test.com',
+            'git://test.com',
+            'github.com/test/test',
+            'git@test.com',
+        ]
+        for u in urls:
+            assert rewrite_build_path(u) == u
+
+    @mock.patch('compose.service.IS_WINDOWS_PLATFORM', True)
+    def test_rewrite_windows_path(self):
+        assert rewrite_build_path('C:\\context') == WINDOWS_LONGPATH_PREFIX + 'C:\\context'
+        assert rewrite_build_path(
+            rewrite_build_path('C:\\context')
+        ) == rewrite_build_path('C:\\context')
+
+    @mock.patch('compose.service.IS_WINDOWS_PLATFORM', False)
+    def test_rewrite_unix_path(self):
+        assert rewrite_build_path('/context') == '/context'