Get layer size if not provided

Docker registry with Manifest v1 does not require the size of layers to
be included. However, when this information is not provided we can use
os.path.getsize() to get and show the size of tarball. We can also
use this function for FileSource to provide consistent output messages.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/virtBootstrap/sources/docker_source.py b/src/virtBootstrap/sources/docker_source.py
index 246356a..2dadb42 100644
--- a/src/virtBootstrap/sources/docker_source.py
+++ b/src/virtBootstrap/sources/docker_source.py
@@ -92,15 +92,14 @@ class DockerSource(object):
             raise ValueError('Unsupported manifest schema.')
 
         for layer in layers_list:
-            layer_digest = layer[digest_field]
-            layer_size = layer['size'] if 'size' in layer else None
-
             # Store checksums of layers
+            layer_digest = layer[digest_field]
             sum_type, layer_sum = layer_digest.split(':')
             self.checksums.append([sum_type, layer_sum])
 
             # Store file path and size of each layer
             file_path = os.path.join(self.images_dir, layer_sum + '.tar')
+            layer_size = layer.get('size', None)
             self.layers.append([file_path, layer_size])
 
     def gen_valid_uri(self, uri):