Enable redirects for ECR blob download requests (#597)

platform_registry_api/api.py

@@ -158,6 +158,10 @@ def __init__(
         self._upstream_endpoint_url = upstream_endpoint_url
         self._upstream_project = upstream_project
 
+    @property
+    def upstream_host(self) -> Optional[str]:
+        return self._upstream_endpoint_url.host
+
     @property
     def upstream_project(self) -> str:
         return self._upstream_project
@@ -689,13 +693,19 @@ async def _proxy_request(
                 )
             return response
         else:
+            aws_blob_request = (
+                request.method == "GET"
+                and self._config.upstream_registry.type == UpstreamType.AWS_ECR
+                and path_components[-1] == "blobs"
+            )
             async with self._registry_client.request(
                 method=request.method,
                 url=url,
                 headers=request_headers,
                 skip_auto_headers=("Content-Type",),
                 data=data,
                 timeout=timeout,
+                allow_redirects=aws_blob_request,
             ) as client_response:
 
                 logger.debug("upstream response: %s", client_response)
@@ -810,6 +820,9 @@ def _prepare_response_headers(
         return response_headers
 
     def _convert_location_header(self, url_str: str, url_factory: URLFactory) -> str:
+        url_raw = URL(url_str)
+        if url_raw.host != url_factory.upstream_host:
+            return url_str  # Redirect to outer service, maybe AWS S3 redirect
         upstream_repo_url = RepoURL.from_url(URL(url_str))
         registry_repo_url = url_factory.create_registry_repo_url(upstream_repo_url)
         logger.info(