Build labels option: array form produces unmarshal error (fixes #5183)

Signed-off-by: Guillermo Arribas <garribas@gmail.com>

compose/service.py

@@ -23,6 +23,7 @@ from . import const
 from . import progress_stream
 from .config import DOCKER_CONFIG_KEYS
 from .config import merge_environment
+from .config.config import parse_labels
 from .config.errors import DependencyError
 from .config.types import ServicePort
 from .config.types import VolumeSpec
@@ -916,7 +917,7 @@ class Service(object):
             nocache=no_cache,
             dockerfile=build_opts.get('dockerfile', None),
             cache_from=build_opts.get('cache_from', None),
-            labels=build_opts.get('labels', None),
+            labels=parse_labels(build_opts.get('labels', None)),
             buildargs=build_args,
             network_mode=build_opts.get('network', None),
             target=build_opts.get('target', None),

tests/integration/service_test.py

@@ -761,7 +761,7 @@ class ServiceTest(DockerClientTestCase):
         assert service.image()
         assert "build_version=2" in service.image()['ContainerConfig']['Cmd']
 
-    def test_build_with_build_labels(self):
+    def test_build_with_build_labels_dict(self):
         base_dir = tempfile.mkdtemp()
         self.addCleanup(shutil.rmtree, base_dir)
 
@@ -778,6 +778,23 @@ class ServiceTest(DockerClientTestCase):
         assert service.image()
         assert service.image()['Config']['Labels']['com.docker.compose.test'] == 'true'
 
+    def test_build_with_build_labels_list(self):
+        base_dir = tempfile.mkdtemp()
+        self.addCleanup(shutil.rmtree, base_dir)
+
+        with open(os.path.join(base_dir, 'Dockerfile'), 'w') as f:
+            f.write('FROM busybox\n')
+
+        service = self.create_service('buildlabels', build={
+            'context': text_type(base_dir),
+            'labels': ['com.docker.compose.test=true']
+        })
+        service.build()
+        self.addCleanup(self.client.remove_image, service.image_name)
+
+        assert service.image()
+        assert service.image()['Config']['Labels']['com.docker.compose.test'] == 'true'
+
     @no_cluster('Container networks not on Swarm')
     def test_build_with_network(self):
         base_dir = tempfile.mkdtemp()

tests/unit/service_test.py

@@ -473,7 +473,7 @@ class ServiceTest(unittest.TestCase):
             nocache=False,
             rm=True,
             buildargs={},
-            labels=None,
+            labels={},
             cache_from=None,
             network_mode=None,
             target=None,
@@ -514,7 +514,7 @@ class ServiceTest(unittest.TestCase):
             nocache=False,
             rm=True,
             buildargs={},
-            labels=None,
+            labels={},
             cache_from=None,
             network_mode=None,
             target=None,