Remove the manifest schema conversion machinery

closes: pulp#1509

CHANGES/1509.removal

@@ -0,0 +1,4 @@
+Removed the manifest schema conversion machinery. If the manifest is stored locally in the newer
+format and old clients request v2 schema1 manifest they will receive 404. v2 schema1 manifest is
+still going to be mirrored from remote source during sync if available and passed to the old clients
+on the request.

docs/workflows/host.rst

@@ -113,10 +113,8 @@ Docker Output::
 
 .. note::
     When using a container client that cannot handle requested manifests in the new format
-    (schema 2), the manifests are rewritten into the old format (schema 1) on-the-fly by Pulp.
-    In general, the automatic conversion cannot be performed when the content is not available
-    in the storage. Therefore, it may be successful only if the content was previously synced
-    with the ``immediate`` policy.
+    (schema 2), the manifests will **not** be rewritten into the old format (schema 1) and Pulp will
+    raise a 404 (HTTPNOTFOUND) error.
 
 
 Pull-Through Caching

pulp_container/app/redirects.py

@@ -3,6 +3,7 @@
 from django.http import Http404
 from django.shortcuts import redirect
 
+from pulp_container.app.exceptions import ManifestNotFound
 from pulp_container.app.utils import get_accepted_media_types
 from pulp_container.constants import BLOB_CONTENT_TYPE, MEDIA_TYPE
 
@@ -38,6 +39,13 @@ def issue_tag_redirect(self, tag):
         """
         Issue a redirect for the passed tag.
         """
+        manifest_media_type = tag.tagged_manifest.media_type
+        if (
+            manifest_media_type not in get_accepted_media_types(self.request.headers)
+            and manifest_media_type != MEDIA_TYPE.MANIFEST_V1
+        ):
+            raise ManifestNotFound(reference=tag.name)
+
         return self.redirect_to_content_app("manifests", tag.name)
 
     def issue_manifest_redirect(self, manifest):
@@ -60,7 +68,8 @@ class S3StorageRedirects(CommonRedirects):
 
     def issue_tag_redirect(self, tag):
         """
-        Issue a redirect or perform a schema conversion if an accepted media type requires it.
+        Issue a redirect if an accepted media type requires it or return not found if manifest
+        version is not supported.
         """
         manifest_media_type = tag.tagged_manifest.media_type
         if manifest_media_type in get_accepted_media_types(self.request.headers):
@@ -70,8 +79,7 @@ def issue_tag_redirect(self, tag):
                 tag.name, tag.tagged_manifest, MEDIA_TYPE.MANIFEST_V1_SIGNED
             )
         else:
-            # execute the schema conversion
-            return self.redirect_to_content_app("manifests", tag.name)
+            raise ManifestNotFound(reference=tag.name)
 
     def issue_manifest_redirect(self, manifest):
         """

pulp_container/app/registry.py

@@ -24,7 +24,6 @@
 
 from pulp_container.app.cache import RegistryContentCache
 from pulp_container.app.models import ContainerDistribution, Tag, Blob, Manifest, BlobManifest
-from pulp_container.app.schema_convert import Schema2toSchema1ConverterWrapper
 from pulp_container.app.tasks import download_image_data
 from pulp_container.app.utils import (
     calculate_digest,
@@ -212,8 +211,8 @@ async def get_tag(self, request):
             }
             return await self.dispatch_tag(request, tag, response_headers)
 
-        # convert if necessary
-        return await Registry.dispatch_converted_schema(tag, accepted_media_types, path)
+        # return 404 in case the client is requesting docker manifest v2 schema 1
+        raise PathNotResolved(tag_name)
 
     async def dispatch_tag(self, request, tag, response_headers):
         """
@@ -239,40 +238,6 @@ async def dispatch_tag(self, request, tag, response_headers):
         else:
             return await Registry._dispatch(artifact, response_headers)
 
-    @staticmethod
-    async def dispatch_converted_schema(tag, accepted_media_types, path):
-        """
-        Convert a manifest from the format schema 2 to the format schema 1.
-
-        The format is converted on-the-go and created resources are not stored for further uses.
-        The conversion is made after each request which does not accept the format for schema 2.
-
-        Args:
-            tag: A tag object which contains reference to tagged manifests and config blobs.
-            accepted_media_types: Accepted media types declared in the accept header.
-            path: A path of a repository.
-
-        Raises:
-            PathNotResolved: There was not found a valid conversion for the specified tag.
-
-        Returns:
-            :class:`aiohttp.web.StreamResponse` or :class:`aiohttp.web.Response`: The response
-                streamed back to the client.
-
-        """
-        schema1_converter = Schema2toSchema1ConverterWrapper(tag, accepted_media_types, path)
-        try:
-            result = await sync_to_async(schema1_converter.convert)()
-        except RuntimeError:
-            raise PathNotResolved(tag.name)
-
-        response_headers = {
-            "Docker-Content-Digest": result.digest,
-            "Content-Type": result.content_type,
-            "Docker-Distribution-API-Version": "registry/2.0",
-        }
-        return web.Response(text=result.text, headers=response_headers)
-
     @RegistryContentCache(
         base_key=lambda req, cac: Registry.find_base_path_cached(req, cac),
         auth=lambda req, cac, bk: Registry.auth_cached(req, cac, bk),