fix: image checks for some oci images fail (#1995)

This occurs because some images (most likely when they support multiple
architectures) have an index instead of just a manifest. An OCI index
refers to a set of images. But when we were checking for images we were
only checking for the manifest and did not have the option to support an
index content type.

renku_notebooks/api/classes/image.py

@@ -3,7 +3,7 @@
 from dataclasses import dataclass, field
 from enum import Enum
 from pathlib import Path
-from typing import Any, Optional
+from typing import Any, Optional, cast
 
 import requests
 from werkzeug.datastructures import WWWAuthenticate
@@ -13,7 +13,8 @@
 
 class ManifestTypes(Enum):
     docker_v2: str = "application/vnd.docker.distribution.manifest.v2+json"
-    oci_v1: str = "application/vnd.oci.image.manifest.v1+json"
+    oci_v1_manifest: str = "application/vnd.oci.image.manifest.v1+json"
+    oci_v1_index: str = "application/vnd.oci.image.index.v1+json"
 
 
 @dataclass
@@ -62,8 +63,19 @@ def get_image_manifest(self, image: "Image") -> Optional[dict[str, Any]]:
             headers["Authorization"] = f"Bearer {token}"
         res = requests.get(image_digest_url, headers=headers)
         if res.status_code != 200:
-            headers["Accept"] = ManifestTypes.oci_v1.value
+            headers["Accept"] = ManifestTypes.oci_v1_manifest.value
             res = requests.get(image_digest_url, headers=headers)
+        if res.status_code != 200:
+            headers["Accept"] = ManifestTypes.oci_v1_index.value
+            res = requests.get(image_digest_url, headers=headers)
+            if res.status_code == 200:
+                index_parsed = res.json()
+                manifest = next(
+                    (man for man in index_parsed.get("manifests", []) if man.get("platform", {}).get("os") == "linux"),
+                    None,
+                )
+                manifest = cast(dict[str, Any] | None, manifest)
+                return manifest
         if res.status_code != 200:
             return None
         return res.json()

tests/unit/test_public_image_checks.py

@@ -183,6 +183,7 @@ def test_public_image_name_parsing(name, expected):
         ("renku/singleuser", True),
         ("madeuprepo/madeupproject:tag", False),
         ("olevski90/oci-image:0.0.1", True),
+        ("ghcr.io/linuxserver/nginx:latest", True)
     ],
 )
 @pytest.mark.integration