Compute digest index and avoid rely on Docker-Content-Digest

Signed-off-by: Valentin Delaye <jonesbusy@users.noreply.github.com>

Author: jonesbusy

.sdkmanrc

@@ -1,2 +1,2 @@
-java=17.0.14-tem
+java=17.0.18-tem
 maven=3.9.12

src/main/java/land/oras/ManifestDescriptor.java

@@ -188,14 +188,24 @@ public static ManifestDescriptor of(String mediaType, String digest, long size)
      * @return The subject
      */
     public static ManifestDescriptor of(Descriptor descriptor) {
-        Objects.requireNonNull(descriptor.getDigest());
+        return of(descriptor, descriptor.getDigest());
+    }
+
+    /**
+     * Create a manifest descriptor with the given digest
+     * @param descriptor The descriptor
+     * @param digest The digest
+     * @return The subject
+     */
+    public static ManifestDescriptor of(Descriptor descriptor, @Nullable String digest) {
         Objects.requireNonNull(descriptor.getSize());
+        Objects.requireNonNull(digest);
         return new ManifestDescriptor(
                 descriptor.getArtifactType() != null
                         ? descriptor.getArtifactType().getMediaType()
                         : null,
                 descriptor.getMediaType(),
-                descriptor.getDigest(),
+                digest,
                 descriptor.getSize(),
                 null,
                 descriptor.getAnnotations());

src/main/java/land/oras/Registry.java

@@ -572,8 +572,19 @@ public Index getIndex(ContainerRef containerRef) {
         if (!isIndexMediaType(contentType)) {
             throw new OrasException("Expected index but got %s".formatted(contentType));
         }
-        ManifestDescriptor manifestDescriptor = ManifestDescriptor.of(descriptor);
-        return Index.fromJson(descriptor.getJson()).withDescriptor(manifestDescriptor);
+        String json = descriptor.getJson();
+        String digest = descriptor.getDigest();
+        if (digest == null) {
+            LOG.debug("Digest missing from header, using from reference");
+            digest = containerRef.getDigest();
+            if (digest == null) {
+                LOG.debug("Digest missing from reference, computing from content");
+                digest = containerRef.getAlgorithm().digest(json.getBytes(StandardCharsets.UTF_8));
+                LOG.debug("Computed index digest: {}", digest);
+            }
+        }
+        ManifestDescriptor manifestDescriptor = ManifestDescriptor.of(descriptor, digest);
+        return Index.fromJson(json).withDescriptor(manifestDescriptor);
     }
 
     @Override

src/test/java/land/oras/PublicECRITCase.java

@@ -22,25 +22,26 @@
 
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
-import java.nio.file.Path;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.api.parallel.Execution;
 import org.junit.jupiter.api.parallel.ExecutionMode;
 
 @Execution(ExecutionMode.CONCURRENT)
 class PublicECRITCase {
 
-    @TempDir
-    Path tempDir;
-
     @Test
-    @Disabled("Failing until #514 is fixed")
     void shouldPullAnonymousIndex() {
+
+        // Via tag
         Registry registry = Registry.builder().build();
         ContainerRef containerRef1 = ContainerRef.parse("public.ecr.aws/docker/library/alpine:latest");
         Index index = registry.getIndex(containerRef1);
         assertNotNull(index);
+
+        // Via digest
+        ContainerRef containerRef2 = ContainerRef.parse(
+                "public.ecr.aws/docker/library/alpine@sha256:25109184c71bdad752c8312a8623239686a9a2071e8825f20acb8f2198c3f659");
+        Index index2 = registry.getIndex(containerRef2);
+        assertNotNull(index2);
     }
 }