Updated image download code to continue if a download fails for a course

Failure to download an image for one course should not stop execution of downloads for other courses. Exception handling is now in place to ensure we do not prematurely exit the program.

LEARNER-2463

course_discovery/apps/course_metadata/management/commands/download_course_images.py

@@ -42,21 +42,25 @@ class Command(BaseCommand):
 
         for course in courses:
             logger.info('Retrieving image for course [%s] from [%s]...', course.key, course.card_image_url)
-            response = requests.get(course.card_image_url)
 
-            if response.status_code == requests.codes.ok:  # pylint: disable=no-member
-                content_type = response.headers['Content-Type'].lower()
-                extension = IMAGE_TYPES.get(content_type)
+            try:
+                response = requests.get(course.card_image_url)
 
-                if extension:
-                    filename = '{uuid}.{extension}'.format(uuid=str(course.uuid), extension=extension)
-                    course.image.save(filename, ContentFile(response.content))
-                    logger.info('Image for course [%s] successfully updated.', course.key)
-                else:
-                    # pylint: disable=line-too-long
-                    msg = 'Image retrieved for course [%s] from [%s] has an unknown content type [%s] and will not be saved.'
-                    logger.error(msg, course.key, course.card_image_url, content_type)
+                if response.status_code == requests.codes.ok:  # pylint: disable=no-member
+                    content_type = response.headers['Content-Type'].lower()
+                    extension = IMAGE_TYPES.get(content_type)
+
+                    if extension:
+                        filename = '{uuid}.{extension}'.format(uuid=str(course.uuid), extension=extension)
+                        course.image.save(filename, ContentFile(response.content))
+                        logger.info('Image for course [%s] successfully updated.', course.key)
+                    else:
+                        # pylint: disable=line-too-long
+                        msg = 'Image retrieved for course [%s] from [%s] has an unknown content type [%s] and will not be saved.'
+                        logger.error(msg, course.key, course.card_image_url, content_type)
 
-            else:
-                msg = 'Failed to download image for course [%s] from [%s]! Response was [%d]:\n%s'
-                logger.error(msg, course.key, course.card_image_url, response.status_code, response.content)
+                else:
+                    msg = 'Failed to download image for course [%s] from [%s]! Response was [%d]:\n%s'
+                    logger.error(msg, course.key, course.card_image_url, response.status_code, response.content)
+            except Exception:  # pylint: disable=broad-except
+                logger.exception('An unknown exception occurred while downloading image for course [%s]', course.key)

course_discovery/apps/course_metadata/management/commands/tests/test_download_course_images.py

@@ -25,6 +25,10 @@ class TestDownloadCourseImages:
         )
         return image_url, body
 
+    def assert_course_has_no_image(self, course):
+        course.refresh_from_db()
+        assert not bool(course.image)
+
     @responses.activate
     def test_download(self):
         image_url, image_content = self.mock_image_response()
@@ -66,9 +70,7 @@ class TestDownloadCourseImages:
             )
 
         assert len(responses.calls) == 1
-
-        course.refresh_from_db()
-        assert not bool(course.image)
+        self.assert_course_has_no_image(course)
 
     @responses.activate
     def test_download_with_invalid_status_code(self):
@@ -88,11 +90,27 @@ class TestDownloadCourseImages:
             )
 
         assert len(responses.calls) == 1
-
-        course.refresh_from_db()
-        assert not bool(course.image)
+        self.assert_course_has_no_image(course)
 
     def test_download_without_courses(self):
         with mock.patch(self.LOGGER_PATH) as mock_logger:
             call_command('download_course_images')
             mock_logger.info.assert_called_with('All courses are up to date.')
+
+    @responses.activate
+    def test_download_with_unexpected_error(self):
+        image_url, __ = self.mock_image_response()
+        course = CourseFactory(card_image_url=image_url, image=None)
+
+        with mock.patch('stdimage.models.StdImageFieldFile.save', side_effect=Exception) as mock_save:
+            with mock.patch(self.LOGGER_PATH) as mock_logger:
+                call_command('download_course_images')
+                mock_logger.exception.assert_called_once_with(
+                    'An unknown exception occurred while downloading image for course [%s]',
+                    course.key
+                )
+
+            mock_save.assert_called_once()
+
+        assert len(responses.calls) == 1
+        self.assert_course_has_no_image(course)