Interpolate environment variables

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

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

@@ -0,0 +1,17 @@
+web:
+  # unbracketed name
+  image: $IMAGE
+
+  # array element
+  ports:
+    - "${HOST_PORT}:8000"
+
+  # dictionary item value
+  labels:
+    mylabel: "${LABEL_VALUE}"
+
+  # unset value
+  hostname: "host-${UNSET_VALUE}"
+
+  # escaped interpolation
+  command: "$${ESCAPED}"

tests/fixtures/volume-path-interpolation/docker-compose.yml

@@ -0,0 +1,5 @@
+test:
+  image: busybox
+  command: top
+  volumes:
+    - "~/${VOLUME_NAME}:/container-path"

tests/integration/cli_test.py

@@ -488,6 +488,21 @@ class CLITestCase(DockerClientTestCase):
         self.assertEqual(len(containers), 1)
         self.assertIn("FOO=1", containers[0].get('Config.Env'))
 
+    @patch.dict(os.environ)
+    def test_home_and_env_var_in_volume_path(self):
+        os.environ['VOLUME_NAME'] = 'my-volume'
+        os.environ['HOME'] = '/tmp/home-dir'
+        expected_host_path = os.path.join(os.environ['HOME'], os.environ['VOLUME_NAME'])
+
+        self.command.base_dir = 'tests/fixtures/volume-path-interpolation'
+        self.command.dispatch(['up', '-d'], None)
+
+        container = self.project.containers(stopped=True)[0]
+        actual_host_path = container.get('Volumes')['/container-path']
+        components = actual_host_path.split('/')
+        self.assertTrue(components[-2:] == ['home-dir', 'my-volume'],
+                        msg="Last two components differ: %s, %s" % (actual_host_path, expected_host_path))
+
     def test_up_with_extends(self):
         self.command.base_dir = 'tests/fixtures/extends'
         self.command.dispatch(['up', '-d'], None)

tests/integration/service_test.py

@@ -273,24 +273,6 @@ class ServiceTest(DockerClientTestCase):
 
         self.assertEqual(service.containers(stopped=False), [new_container])
 
-    @patch.dict(os.environ)
-    def test_create_container_with_home_and_env_var_in_volume_path(self):
-        os.environ['VOLUME_NAME'] = 'my-volume'
-        os.environ['HOME'] = '/tmp/home-dir'
-        expected_host_path = os.path.join(os.environ['HOME'], os.environ['VOLUME_NAME'])
-
-        host_path = '~/${VOLUME_NAME}'
-        container_path = '/container-path'
-
-        service = self.create_service('db', volumes=['%s:%s' % (host_path, container_path)])
-        container = service.create_container()
-        service.start_container(container)
-
-        actual_host_path = container.get('Volumes')[container_path]
-        components = actual_host_path.split('/')
-        self.assertTrue(components[-2:] == ['home-dir', 'my-volume'],
-                        msg="Last two components differ: %s, %s" % (actual_host_path, expected_host_path))
-
     def test_create_container_with_volumes_from(self):
         volume_service = self.create_service('data')
         volume_container_1 = volume_service.create_container()

tests/unit/config_test.py

@@ -59,11 +59,56 @@ class ConfigTest(unittest.TestCase):
         make_service_dict('foo', {'ports': ['8000']}, 'tests/')
 
 
-class VolumePathTest(unittest.TestCase):
+class InterpolationTest(unittest.TestCase):
     @mock.patch.dict(os.environ)
-    def test_volume_binding_with_environ(self):
+    def test_config_file_with_environment_variable(self):
+        os.environ.update(
+            IMAGE="busybox",
+            HOST_PORT="80",
+            LABEL_VALUE="myvalue",
+        )
+
+        service_dicts = config.load(
+            config.find('tests/fixtures/environment-interpolation', None),
+        )
+
+        self.assertEqual(service_dicts, [
+            {
+                'name': 'web',
+                'image': 'busybox',
+                'ports': ['80:8000'],
+                'labels': {'mylabel': 'myvalue'},
+                'hostname': 'host-',
+                'command': '${ESCAPED}',
+            }
+        ])
+
+    @mock.patch.dict(os.environ)
+    def test_invalid_interpolation(self):
+        with self.assertRaises(config.ConfigurationError) as cm:
+            config.load(
+                config.ConfigDetails(
+                    {'web': {'image': '${'}},
+                    'working_dir',
+                    'filename.yml'
+                )
+            )
+
+        self.assertIn('Invalid', cm.exception.msg)
+        self.assertIn('for "image" option', cm.exception.msg)
+        self.assertIn('in service "web"', cm.exception.msg)
+        self.assertIn('"${"', cm.exception.msg)
+
+    @mock.patch.dict(os.environ)
+    def test_volume_binding_with_environment_variable(self):
         os.environ['VOLUME_PATH'] = '/host/path'
-        d = make_service_dict('foo', {'volumes': ['${VOLUME_PATH}:/container/path']}, working_dir='.')
+        d = config.load(
+            config.ConfigDetails(
+                config={'foo': {'volumes': ['${VOLUME_PATH}:/container/path']}},
+                working_dir='.',
+                filename=None,
+            )
+        )[0]
         self.assertEqual(d['volumes'], ['/host/path:/container/path'])
 
     @mock.patch.dict(os.environ)
@@ -400,18 +445,22 @@ class EnvTest(unittest.TestCase):
         os.environ['HOSTENV'] = '/tmp'
         os.environ['CONTAINERENV'] = '/host/tmp'
 
-        service_dict = make_service_dict(
-            'foo',
-            {'volumes': ['$HOSTENV:$CONTAINERENV']},
-            working_dir="tests/fixtures/env"
-        )
+        service_dict = config.load(
+            config.ConfigDetails(
+                config={'foo': {'volumes': ['$HOSTENV:$CONTAINERENV']}},
+                working_dir="tests/fixtures/env",
+                filename=None,
+            )
+        )[0]
         self.assertEqual(set(service_dict['volumes']), set(['/tmp:/host/tmp']))
 
-        service_dict = make_service_dict(
-            'foo',
-            {'volumes': ['/opt${HOSTENV}:/opt${CONTAINERENV}']},
-            working_dir="tests/fixtures/env"
-        )
+        service_dict = config.load(
+            config.ConfigDetails(
+                config={'foo': {'volumes': ['/opt${HOSTENV}:/opt${CONTAINERENV}']}},
+                working_dir="tests/fixtures/env",
+                filename=None,
+            )
+        )[0]
         self.assertEqual(set(service_dict['volumes']), set(['/opt/tmp:/opt/host/tmp']))
 
 

tests/unit/interpolation_test.py

@@ -0,0 +1,31 @@
+import unittest
+
+from compose.config.interpolation import interpolate, InvalidInterpolation
+
+
+class InterpolationTest(unittest.TestCase):
+    def test_valid_interpolations(self):
+        self.assertEqual(interpolate('$foo', dict(foo='hi')), 'hi')
+        self.assertEqual(interpolate('${foo}', dict(foo='hi')), 'hi')
+
+        self.assertEqual(interpolate('${subject} love you', dict(subject='i')), 'i love you')
+        self.assertEqual(interpolate('i ${verb} you', dict(verb='love')), 'i love you')
+        self.assertEqual(interpolate('i love ${object}', dict(object='you')), 'i love you')
+
+    def test_empty_value(self):
+        self.assertEqual(interpolate('${foo}', dict(foo='')), '')
+
+    def test_unset_value(self):
+        self.assertEqual(interpolate('${foo}', dict()), '')
+
+    def test_escaped_interpolation(self):
+        self.assertEqual(interpolate('$${foo}', dict(foo='hi')), '${foo}')
+
+    def test_invalid_strings(self):
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('$}', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${}', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${ }', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${ foo}', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${foo }', dict()))
+        self.assertRaises(InvalidInterpolation, lambda: interpolate('${foo!}', dict()))