feat: add support for single arch with attestation (#674)

Add seamless support for single arch OCI archives that contain an attestation manifest

Author: bgardiner

lib/extractor/oci-archive/layer.ts

@@ -133,9 +133,14 @@ function getLayersContentAndArchiveManifest(
   manifest: OciArchiveManifest;
   imageConfig: ImageConfig;
 } {
+  const filteredConfigs = configs.filter((config) => {
+    return config?.os !== "unknown" || config?.architecture !== "unknown";
+  });
   const platform =
     options?.platform ||
-    (configs.length === 1 ? getPlatformFromConfig(configs[0]) : "linux/amd64");
+    (filteredConfigs.length === 1
+      ? getPlatformFromConfig(filteredConfigs[0])
+      : "linux/amd64");
   const platformInfo = getOciPlatformInfoFromOptionString(platform as string);
 
   // get manifest file first

test/fixtures/containerd-archives/busybox-single-arch-with-attestation-manifest.tar

@@ -154,6 +154,15 @@ describe("extractImageContent", () => {
           extractImageContent(type, fixture, [], { platform: "linux/arm/v4" }),
         ).rejects.toThrow();
       });
+
+      it("succeeds for single platform image containing an attestation manifest", async () => {
+        const fixture = getFixture(
+          "containerd-archives/busybox-single-arch-with-attestation-manifest.tar",
+        );
+        await expect(
+          extractImageContent(type, fixture, [], {}),
+        ).resolves.not.toThrow();
+      });
     });
   });
 });