Use standard-ish image_inspect format

repo2docker/app.py

@@ -597,7 +597,7 @@ class Repo2Docker(Application):
         container_volumes = {}
         if self.volumes:
             image = client.inspect_image(self.output_image_spec)
-            image_workdir = image["ContainerConfig"]["WorkingDir"]
+            image_workdir = image.config["WorkingDir"]
 
             for k, v in self.volumes.items():
                 container_volumes[os.path.abspath(k)] = {

repo2docker/docker.py

@@ -86,7 +86,8 @@ class DockerEngine(ContainerEngine):
         return [Image(tags=image["RepoTags"]) for image in images]
 
     def inspect_image(self, image):
-        return self._apiclient.inspect_image(image)
+        image = self._apiclient.inspect_image(image)
+        return Image(tags=image["RepoTags"], config=image["ContainerConfig"])
 
     def push(self, image_spec):
         return self._apiclient.push(image_spec, stream=True)

repo2docker/engine.py

@@ -89,8 +89,9 @@ class Image:
     Information about a container image
     """
 
-    def __init__(self, *, tags):
+    def __init__(self, *, tags, config=None):
         self._tags = tags or []
+        self._config = config
 
     @property
     def tags(self):
@@ -102,8 +103,19 @@ class Image:
         """
         return self._tags
 
+    @property
+    def config(self):
+        """
+        A dictionary of image configuration information
+
+        If this is `None` the information has not been loaded.
+        If not `None` this must include the following fields:
+        - WorkingDir: The default working directory
+        """
+        return self._config
+
     def __repr__(self):
-        return "Image(tags={})".format(self.tags)
+        return "Image(tags={},config={})".format(self.tags, self.config)
 
 
 class ContainerEngine(LoggingConfigurable):
@@ -211,7 +223,7 @@ class ContainerEngine(LoggingConfigurable):
 
         Returns
         -------
-        dict
+        Image object with .config dict.
         """
         raise NotImplementedError("inspect_image not implemented")