Check and return errors while validating science image.

Fixes ssl-hep#540.

Author: draghuram

servicex_app/servicex/docker_repo_adapter.py

@@ -35,23 +35,29 @@ class DockerRepoAdapter:
     def __init__(self, registry_endpoint="https://hub.docker.com"):
         self.registry_endpoint = registry_endpoint
 
-    def check_image_exists(self, tagged_image: str) -> bool:
+    def check_image_exists(self, tagged_image: str) -> (bool, str):
         """
         Checks that the given Docker image
         :param tagged_image: Full Docker image name, e.g. "sslhep/servicex_app:latest".
         :return: Whether or not the image exists in the registry.
         """
         search_result = re.search("(.+)/(.+):(.+)", tagged_image)
         if not search_result or len(search_result.groups()) != 3:
-            return False
+            return False, f"Requested transformer docker image is not in the right format: {tagged_image}"
 
         (repo, image, tag) = search_result.groups()
 
         query = f'{self.registry_endpoint}/v2/repositories/{repo}/{image}/tags/{tag}'
         r = requests.get(query)
+
+        if r.status_code >= 200 and r.status_code < 300:
+            current_app.logger.info(f"Requested Image: {tagged_image} exists, "
+                                    f"last updated {r.json()['last_updated']}")
+            return True, ""
+
         if r.status_code == 404:
-            return False
+            return False, f"Requested transformer docker image doesn't exist: {tagged_image}"
+
+        msg = f"Unexpected error in validating transformer docker image ({tagged_image}), status_code: {r.status_code}, msg ({r.content})"
+        return False, msg
 
-        current_app.logger.info(f"Requested Image: {tagged_image} exists, "
-                                f"last updated {r.json()['last_updated']}")
-        return True

servicex_app/servicex/resources/transformation/submit.py

@@ -150,8 +150,8 @@ def post(self):
                     request_rec.image = codegen_transformer_image
 
             if config['TRANSFORMER_VALIDATE_DOCKER_IMAGE']:
-                if not self.docker_repo_adapter.check_image_exists(request_rec.image):
-                    msg = f"Requested transformer docker image doesn't exist: {request_rec.image}"
+                exists, msg = self.docker_repo_adapter.check_image_exists(request_rec.image)
+                if not exists:
                     current_app.logger.error(msg, extra={'requestId': request_id})
                     return {'message': msg}, 400