Added env var parsing to volume container paths

This commit adds environment variable parsing to the container side
of the volume mapping in configs. The common use case for this is
mounting SSH agent sockets in a container, using code like:

volumes:
    - $SSH_AUTH_SOCK:$SSH_AUTH_SOCK
environment:
    - SSH_AUTH_SOCK

Signed-off-by: Jeff Kramer <[email protected]>

compose/config.py

@@ -184,7 +184,7 @@ def process_container_options(service_dict, working_dir=None):
     service_dict = service_dict.copy()
 
     if 'volumes' in service_dict:
-        service_dict['volumes'] = resolve_host_paths(service_dict['volumes'], working_dir=working_dir)
+        service_dict['volumes'] = resolve_volume_paths(service_dict['volumes'], working_dir=working_dir)
 
     if 'build' in service_dict:
         service_dict['build'] = resolve_build_path(service_dict['build'], working_dir=working_dir)
@@ -345,18 +345,18 @@ def env_vars_from_file(filename):
     return env
 
 
-def resolve_host_paths(volumes, working_dir=None):
+def resolve_volume_paths(volumes, working_dir=None):
     if working_dir is None:
-        raise Exception("No working_dir passed to resolve_host_paths()")
+        raise Exception("No working_dir passed to resolve_volume_paths()")
 
-    return [resolve_host_path(v, working_dir) for v in volumes]
+    return [resolve_volume_path(v, working_dir) for v in volumes]
 
 
-def resolve_host_path(volume, working_dir):
+def resolve_volume_path(volume, working_dir):
     container_path, host_path = split_path_mapping(volume)
+    container_path = os.path.expanduser(os.path.expandvars(container_path))
     if host_path is not None:
-        host_path = os.path.expanduser(host_path)
-        host_path = os.path.expandvars(host_path)
+        host_path = os.path.expanduser(os.path.expandvars(host_path))
         return "%s:%s" % (expand_path(working_dir, host_path), container_path)
     else:
         return container_path

tests/unit/config_test.py

@@ -334,6 +334,25 @@ class EnvTest(unittest.TestCase):
             {'FILE_DEF': 'F1', 'FILE_DEF_EMPTY': '', 'ENV_DEF': 'E3', 'NO_DEF': ''},
         )
 
+    @mock.patch.dict(os.environ)
+    def test_resolve_path(self):
+        os.environ['HOSTENV'] = '/tmp'
+        os.environ['CONTAINERENV'] = '/host/tmp'
+
+        service_dict = config.make_service_dict(
+            'foo',
+            {'volumes': ['$HOSTENV:$CONTAINERENV']},
+            working_dir="tests/fixtures/env"
+        )
+        self.assertEqual(set(service_dict['volumes']), set(['/tmp:/host/tmp']))
+
+        service_dict = config.make_service_dict(
+            'foo',
+            {'volumes': ['/opt${HOSTENV}:/opt${CONTAINERENV}']},
+            working_dir="tests/fixtures/env"
+        )
+        self.assertEqual(set(service_dict['volumes']), set(['/opt/tmp:/opt/host/tmp']))
+
 
 class ExtendsTest(unittest.TestCase):
     def test_extends(self):