Do not rely on Docker-Content-Digest when getting manifests

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

@@ -553,8 +553,19 @@ public Manifest getManifest(ContainerRef containerRef) {
             throw new OrasException(
                     "Expected manifest but got index. Probably a multi-platform image instead of artifact");
         }
-        ManifestDescriptor manifestDescriptor = ManifestDescriptor.of(descriptor);
-        return Manifest.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 Manifest.fromJson(json).withDescriptor(manifestDescriptor);
     }
 
     @Override
@@ -649,7 +660,7 @@ private void validateDockerContentDigest(HttpClient.ResponseWrapper<String> resp
         // We need a way to propagate the headers like scoped.
         // For now just skip validation
         if (digest == null) {
-            LOG.warn("Docker-Content-Digest header not found in response. Skipping validation.");
+            LOG.debug("Docker-Content-Digest header not found in response. Skipping validation.");
             return;
         }
         String computedDigest = SupportedAlgorithm.fromDigest(digest).digest(data);
@@ -662,7 +673,7 @@ private void validateDockerContentDigest(HttpClient.ResponseWrapper<Path> respon
         // We need a way to propagate the headers like scoped.
         // For now just skip validation
         if (digest == null) {
-            LOG.warn("Docker-Content-Digest header not found in response. Skipping validation.");
+            LOG.debug("Docker-Content-Digest header not found in response. Skipping validation.");
             return;
         }
         String computedDigest = SupportedAlgorithm.fromDigest(digest).digest(path);
@@ -679,7 +690,7 @@ private void validateDockerContentDigest(HttpClient.ResponseWrapper<Path> respon
         // We need a way to propagate the headers like scoped.
         // For now just skip validation
         if (digest == null) {
-            LOG.warn("Docker-Content-Digest header not found in response. Skipping validation.");
+            LOG.debug("Docker-Content-Digest header not found in response. Skipping validation.");
             return null;
         }
         SupportedAlgorithm.fromDigest(digest);

src/test/java/land/oras/GitHubContainerRegistryITCase.java

@@ -43,6 +43,15 @@ void shouldPullIndex() {
         assertNotNull(index);
     }
 
+    @Test
+    void shouldPUllManifest() {
+        Registry registry = Registry.builder().build();
+        ContainerRef containerRef1 = ContainerRef.parse(
+                "ghcr.io/oras-project/oras@sha256:fd4c818e80ea594cbd39ca47dc05067c8c5690c4eee6c8aee48c508290a5a0c0");
+        Manifest manifest = registry.getManifest(containerRef1);
+        assertNotNull(manifest);
+    }
+
     @Test
     void shouldPullOneBlob() throws IOException {
         Registry registry = Registry.builder().build();

src/test/java/land/oras/HarborS3ITCase.java

@@ -29,14 +29,28 @@
 import org.junit.jupiter.api.parallel.Execution;
 import org.junit.jupiter.api.parallel.ExecutionMode;
 
+/**
+ * Test disabled due to authentication
+ * mkdir lib && touch lib/a
+ * oras push demo.goharbor.io/oras/lib:foo lib
+ */
 @Execution(ExecutionMode.CONCURRENT)
 class HarborS3ITCase {
 
     @TempDir
     Path tempDir;
 
     @Test
-    @Disabled("Only to test with demo Harbor S3 instance")
+    @Disabled("Only to test with demo Harbor demo instance")
+    void shouldGetManifest() {
+        Registry registry = Registry.builder().defaults().build();
+        ContainerRef containerRef1 = ContainerRef.parse("demo.goharbor.io/oras/lib:foo");
+        Manifest manifest = registry.getManifest(containerRef1);
+        assertNotNull(manifest);
+    }
+
+    @Test
+    @Disabled("Only to test with demo Harbor demo instance")
     void shouldPullOneBlob() {
         Registry registry = Registry.builder().defaults().build();
         ContainerRef containerRef1 = ContainerRef.parse("demo.goharbor.io/oras/lib:foo");

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

@@ -22,7 +22,6 @@
 
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.parallel.Execution;
 import org.junit.jupiter.api.parallel.ExecutionMode;
@@ -47,13 +46,20 @@ void shouldPullAnonymousIndex() {
     }
 
     @Test
-    @Disabled("https://github.com/oras-project/oras-java/issues/522")
     void shouldPullManifest() {
-        Registry registry = Registry.builder().build();
-        ContainerRef containerRef = ContainerRef.parse(
+
+        // Via tag
+        Registry registry1 = Registry.builder().build();
+        ContainerRef containerRef1 = ContainerRef.parse("public.ecr.aws/bitnami/contour-operator:latest");
+        Manifest manifest1 = registry1.getManifest(containerRef1);
+        assertNotNull(manifest1);
+
+        // Via digest
+        Registry registry2 = Registry.builder().build();
+        ContainerRef containerRef2 = ContainerRef.parse(
                 "public.ecr.aws/docker/library/alpine@sha256:59855d3dceb3ae53991193bd03301e082b2a7faa56a514b03527ae0ec2ce3a95");
-        Manifest manifest = registry.getManifest(containerRef);
-        assertNotNull(manifest);
+        Manifest manifest2 = registry2.getManifest(containerRef2);
+        assertNotNull(manifest2);
     }
 
     @Test