Treat 'No space left on device' error as fatal

Fail without retries when Errno 28 - "No space left
on device" error is encountered.

Closes-Bug: #2094854
Change-Id: Ie84b422916ddc02f2474164fe3da083324ef4824

ironic_python_agent/errors.py

@@ -156,6 +156,11 @@ class ImageDownloadError(RESTError):
         super(ImageDownloadError, self).__init__(details)
 
 
+class ImageDownloadOutofSpaceError(ImageDownloadError):
+    """Raised when an image download fails due to insufficient storage."""
+    pass
+
+
 class ImageChecksumError(RESTError):
     """Error raised when an image fails to verify against its checksum."""
 

ironic_python_agent/extensions/standby.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import errno
 import hashlib
 import os
 import re
@@ -679,6 +680,8 @@ def _download_image(image_info):
 
     :param image_info: Image information dictionary.
     :raises: ImageDownloadError if the image download fails for any reason.
+    :raises: ImageDownloadOutofSpaceError if the image download fails
+             due to insufficient storage space.
     :raises: ImageChecksumError if the downloaded image's checksum does not
              match the one reported in image_info.
     """
@@ -691,12 +694,24 @@ def _download_image(image_info):
             with open(image_location, 'wb') as f:
                 try:
                     for chunk in image_download:
-                        f.write(chunk)
+                        try:
+                            f.write(chunk)
+                        except OSError as e:
+                            if e.errno == errno.ENOSPC:
+                                msg = ('Unable to write image to {}. Error: {}'
+                                       ).format(image_location, str(e))
+                                raise errors.ImageDownloadOutofSpaceError(
+                                    image_info['id'], msg)
+                            raise
                 except Exception as e:
+                    if isinstance(e, errors.ImageDownloadOutofSpaceError):
+                        raise
                     msg = 'Unable to write image to {}. Error: {}'.format(
                         image_location, str(e))
                     raise errors.ImageDownloadError(image_info['id'], msg)
             image_download.verify_image(image_location)
+        except errors.ImageDownloadOutofSpaceError:
+            raise
         except (errors.ImageDownloadError,
                 errors.ImageChecksumError) as e:
             if attempt == CONF.image_download_connection_retries:

ironic_python_agent/tests/unit/extensions/test_standby.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import errno
 import os
 import tempfile
 import time
@@ -1775,6 +1776,36 @@ class TestImageDownload(base.IronicAgentTest):
         sleep_mock.assert_called_with(10)
         self.assertEqual(2, sleep_mock.call_count)
 
+    @mock.patch('time.sleep', autospec=True)
+    def test_download_image_no_space_error_fatal(self, sleep_mock,
+                                                 requests_mock, hash_mock):
+        content = ['SpongeBob', 'SquarePants']
+        response = requests_mock.return_value
+        response.status_code = 200
+        response.iter_content.return_value = content
+
+        image_info = _build_fake_image_info()
+        hash_mock.return_value.hexdigest.return_value = image_info[
+            'os_hash_value']
+
+        mock_open = mock.mock_open()
+        mock_file = mock_open.return_value.__enter__.return_value
+        mock_file.write.side_effect = OSError(errno.ENOSPC,
+                                              'No space left on device')
+
+        with mock.patch('builtins.open', mock_open):
+            self.assertRaises(
+                errors.ImageDownloadOutofSpaceError,
+                standby._download_image,
+                image_info
+            )
+
+        requests_mock.assert_called_once_with(image_info['urls'][0],
+                                              cert=None, verify=True,
+                                              stream=True, proxies={},
+                                              timeout=60)
+        sleep_mock.assert_not_called()
+
     @mock.patch.object(standby.LOG, 'warning', autospec=True)
     def test_download_image_and_checksum(self, warn_mock, requests_mock,
                                          hash_mock):

releasenotes/notes/no-retry-disk-space-errors-a24c29b336fd11d9.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fail fast when encountering disk space errors during image
+    downloads instead of attempting futile retries.