Don't break when interpolating environment with unicode characters

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

compose/service.py

@@ -1109,6 +1109,8 @@ def format_environment(environment):
     def format_env(key, value):
         if value is None:
             return key
+        if isinstance(value, six.binary_type):
+            value = value.decode('utf-8')
         return '{key}={value}'.format(key=key, value=value)
     return [format_env(*item) for item in environment.items()]
 

tests/acceptance/cli_test.py

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
@@ -12,6 +13,7 @@ from collections import namedtuple
 from operator import attrgetter
 
 import py
+import six
 import yaml
 from docker import errors
 
@@ -1286,6 +1288,23 @@ class CLITestCase(DockerClientTestCase):
             'simplecomposefile_simple_run_1',
             'exited'))
 
+    @mock.patch.dict(os.environ)
+    def test_run_unicode_env_values_from_system(self):
+        value = 'ą, ć, ę, ł, ń, ó, ś, ź, ż'
+        if six.PY2:  # os.environ doesn't support unicode values in Py2
+            os.environ['BAR'] = value.encode('utf-8')
+        else:  # ... and doesn't support byte values in Py3
+            os.environ['BAR'] = value
+        self.base_dir = 'tests/fixtures/unicode-environment'
+        result = self.dispatch(['run', 'simple'])
+
+        if six.PY2:  # Can't retrieve output on Py3. See issue #3670
+            assert value == result.stdout.strip()
+
+        container = self.project.containers(one_off=OneOffFilter.only, stopped=True)[0]
+        environment = container.get('Config.Env')
+        assert 'FOO={}'.format(value) in environment
+
     @mock.patch.dict(os.environ)
     def test_run_env_values_from_system(self):
         os.environ['FOO'] = 'bar'

tests/fixtures/unicode-environment/docker-compose.yml

@@ -0,0 +1,7 @@
+version: '2'
+services:
+  simple:
+    image: busybox:latest
+    command: sh -c 'echo $$FOO'
+    environment:
+      FOO: ${BAR}