Log required troubleshooting info on image dl fail

Currently, we only log the image ID and attempted URL. Now, we log the
status code recieved and detailed information about how and when things
failed.

Change-Id: I718c7facbe1500d98be78b7b6137e92fdfb2fdf1
Closes-bug: 1420981
Depends-On: I69f6f6eef4ad573f406d64d579a9811c70ac5d28

3 files changed, 17 insertions, 10 deletions

diff --git a/ironic_python_agent/errors.py b/ironic_python_agent/errors.py
index 5ec2e3bf..f21678d4 100644
--- a/ironic_python_agent/errors.py
+++ b/ironic_python_agent/errors.py
@@ -137,8 +137,8 @@ class ImageDownloadError(RESTError):
 
     message = 'Error downloading image.'
 
-    def __init__(self, image_id):
-        details = 'Could not download image with id {0}.'.format(image_id)
+    def __init__(self, image_id, msg):
+        details = 'Download of image id {0} failed: {1}'.format(image_id, msg)
         super(ImageDownloadError, self).__init__(details)
 
 
diff --git a/ironic_python_agent/extensions/standby.py b/ironic_python_agent/extensions/standby.py
index 4b02f143..b792d177 100644
--- a/ironic_python_agent/extensions/standby.py
+++ b/ironic_python_agent/extensions/standby.py
@@ -119,7 +119,9 @@ def _write_configdrive_to_partition(configdrive, device):
 def _request_url(image_info, url):
     resp = requests.get(url, stream=True)
     if resp.status_code != 200:
-        raise errors.ImageDownloadError(image_info['id'])
+        msg = ('Received status code {0} from {1}, expected 200. Response '
+               'body: {2}').format(resp.status_code, url, resp.text)
+        raise errors.ImageDownloadError(image_info['id'], msg)
     return resp
 
 
@@ -130,23 +132,27 @@ def _download_image(image_info):
         try:
             LOG.info("Attempting to download image from {0}".format(url))
             resp = _request_url(image_info, url)
-        except errors.ImageDownloadError:
+        except errors.ImageDownloadError as e:
             failtime = time.time() - starttime
-            log_msg = "Image download failed. URL: {0}; time: {1} seconds"
-            LOG.warning(log_msg.format(url, failtime))
+            log_msg = ('Image download failed. URL: {0}; time: {1} seconds. '
+                       'Error: {2}')
+            LOG.warning(log_msg.format(url, failtime, e.details))
             continue
         else:
             break
     if resp is None:
-        raise errors.ImageDownloadError(image_info['id'])
+        msg = 'Image download failed for all URLs.'
+        raise errors.ImageDownloadError(image_info['id'], msg)
 
     image_location = _image_location(image_info)
     with open(image_location, 'wb') as f:
         try:
             for chunk in resp.iter_content(IMAGE_CHUNK_SIZE):
                 f.write(chunk)
-        except Exception:
-            raise errors.ImageDownloadError(image_info['id'])
+        except Exception as e:
+            msg = 'Unable to write image to {0}. Error: {1}'.format(
+                    image_location, str(e))
+            raise errors.ImageDownloadError(image_info['id'], msg)
 
     totaltime = time.time() - starttime
     LOG.info("Image downloaded from {0} in {1} seconds".format(image_location,
diff --git a/ironic_python_agent/tests/errors.py b/ironic_python_agent/tests/errors.py
index b36cad86..b49ee67d 100644
--- a/ironic_python_agent/tests/errors.py
+++ b/ironic_python_agent/tests/errors.py
@@ -93,7 +93,8 @@ class TestErrors(test_base.BaseTestCase):
                  (errors.LookupNodeError(DETAILS), SAME_DETAILS),
                  (errors.LookupAgentIPError(DETAILS), SAME_DETAILS),
                  (errors.LookupAgentInterfaceError(DETAILS), SAME_DETAILS),
-                 (errors.ImageDownloadError('image_id'), DIFF_CL_DETAILS),
+                 (errors.ImageDownloadError('image_id', DETAILS),
+                     DIFF_CL_DETAILS),
                  (errors.ImageChecksumError('image_id'), DIFF_CL_DETAILS),
                  (errors.ImageWriteError('device', 'exit_code', 'stdout',
                                          'stderr'),