Raise exception when override.yaml & override.yml coexist

Signed-off-by: Eli Atzaba <eliat123@gmail.com>

compose/config/config.py

@@ -24,6 +24,7 @@ from .environment import split_env
 from .errors import CircularReference
 from .errors import ComposeFileNotFound
 from .errors import ConfigurationError
+from .errors import DuplicateOverrideFileFound
 from .errors import VERSION_EXPLANATION
 from .interpolation import interpolate_environment_variables
 from .sort_services import get_container_name_from_network_mode
@@ -292,11 +293,12 @@ def get_default_config_files(base_dir):
 
 
 def get_default_override_file(path):
-    for default_override_filename in DEFAULT_OVERRIDE_FILENAMES:
-        override_filename = os.path.join(path, default_override_filename)
-        if os.path.exists(override_filename):
-            return [override_filename]
-    return []
+    override_files_in_path = [os.path.join(path, override_filename) for override_filename
+                              in DEFAULT_OVERRIDE_FILENAMES
+                              if os.path.exists(os.path.join(path, override_filename))]
+    if len(override_files_in_path) > 1:
+        raise DuplicateOverrideFileFound(override_files_in_path)
+    return override_files_in_path
 
 
 def find_candidates_in_parent_dirs(filenames, path):

compose/config/errors.py

@@ -44,3 +44,15 @@ class ComposeFileNotFound(ConfigurationError):
 
         Supported filenames: %s
         """ % ", ".join(supported_filenames))
+
+
+class DuplicateOverrideFileFound(ConfigurationError):
+    def __init__(self, override_filenames):
+        self.override_filenames = override_filenames
+
+    @property
+    def msg(self):
+        return """
+        Unable to determine with duplicate override files, only a single override file can be used.
+        Found: %s
+        """ % ", ".join(self.override_filenames)

tests/acceptance/cli_test.py

@@ -21,6 +21,7 @@ from docker import errors
 from .. import mock
 from ..helpers import create_host_file
 from compose.cli.command import get_project
+from compose.config.errors import DuplicateOverrideFileFound
 from compose.container import Container
 from compose.project import OneOffFilter
 from compose.utils import nanoseconds_from_time_seconds
@@ -31,7 +32,6 @@ from tests.integration.testcases import v2_1_only
 from tests.integration.testcases import v2_only
 from tests.integration.testcases import v3_only
 
-
 ProcessResult = namedtuple('ProcessResult', 'stdout stderr')
 
 
@@ -2165,3 +2165,9 @@ class CLITestCase(DockerClientTestCase):
         web, db = containers
         self.assertEqual(web.human_readable_command, 'sleep 100')
         self.assertEqual(db.human_readable_command, 'top')
+
+    def test_up_with_duplicate_override_yaml_files(self):
+        self.base_dir = 'tests/fixtures/duplicate-override-yaml-files'
+        with self.assertRaises(DuplicateOverrideFileFound):
+            get_project(self.base_dir, [])
+        self.base_dir = None

tests/fixtures/duplicate-override-yaml-files/docker-compose.override.yaml

@@ -0,0 +1,3 @@
+
+db:
+    command: "top"

tests/fixtures/duplicate-override-yaml-files/docker-compose.override.yml

@@ -0,0 +1,3 @@
+
+db:
+    command: "sleep 300"

tests/fixtures/duplicate-override-yaml-files/docker-compose.yml

@@ -0,0 +1,10 @@
+
+web:
+    image: busybox:latest
+    command: "sleep 100"
+    links:
+        - db
+
+db:
+    image: busybox:latest
+    command: "sleep 200"