Support hierarchical credentials on AuthStore (per namespace, per repository etc)

src/main/java/land/oras/auth/AuthStore.java

@@ -209,22 +209,45 @@ public static Config load(List<ConfigFile> configFiles) throws OrasException {
 
         /**
          * Retrieves the {@code Credential} associated with the specified containerRef.
+         * Implements hierarchical credential lookup from most-specific to least-specific.
+         * For example, "my-registry.local/namespace/user/image:latest" is looked up as:
+         * <ol>
+         *   <li>my-registry.local/namespace/user/image</li>
+         *   <li>my-registry.local/namespace/user</li>
+         *   <li>my-registry.local/namespace</li>
+         *   <li>my-registry.local</li>
+         * </ol>
          *
          * @param containerRef The containerRef whose credential is to be retrieved.
          * @return The {@code Credential} associated with the containerRef, or {@code null} if no credential is found.
          */
         public @Nullable Credential getCredential(ContainerRef containerRef) throws OrasException {
             String registry = containerRef.getRegistry();
 
-            LOG.debug("Looking for credentials for registry '{}'", registry);
+            // Start at the most specific key: registry/namespace/repository (or registry/repository)
+            String key = registry + "/" + containerRef.getFullRepository();
 
-            // Check direct credential first
-            Credential cred = credentialStore.get(registry);
-            if (cred != null) {
-                return cred;
+            LOG.debug("Looking for credentials for containerRef starting at key '{}'", key);
+
+            // Iterate from most-specific to least-specific, stopping when only the registry remains
+            while (!key.equals(registry)) {
+                Credential cred = credentialStore.get(key);
+                if (cred != null) {
+                    LOG.debug("Found credential for key '{}'", key);
+                    return cred;
+                }
+                // Remove the last path segment and continue with the less specific key
+                key = key.substring(0, key.lastIndexOf('/'));
             }
 
-            // Then, try credential helper
+            // Check the registry-only key
+            Credential registryCred = credentialStore.get(key);
+            if (registryCred != null) {
+                LOG.debug("Found credential for registry '{}'", key);
+                return registryCred;
+            }
+
+            // Try credential helper scoped to the registry
             String helperSuffix = credentialHelperStore.get(registry);
             if (helperSuffix != null) {
                 try {
@@ -234,6 +257,7 @@ public static Config load(List<ConfigFile> configFiles) throws OrasException {
                     LOG.warn("Failed to get credential from helper for registry {}: {}", registry, e.getMessage());
                 }
             }
+
             // Finally, try all-registries helper
             helperSuffix = credentialHelperStore.get(ALL_REGISTRIES_HELPER);
             if (helperSuffix != null) {

src/test/java/land/oras/auth/AuthStoreTest.java

@@ -272,6 +272,90 @@ void testShouldReadCredentialsFromPodManConfig() throws Exception {
                 });
     }
 
+    // language=json
+    public static final String SAMPLE_HIERARCHICAL_CONFIG =
+            """
+    {
+        "auths": {
+            "my-registry.local/namespace/user/image": {
+                "auth": "dXNlcjE6cGFzczE="
+            },
+            "my-registry.local/namespace": {
+                "auth": "dXNlcjM6cGFzczM="
+            },
+            "my-registry.local": {
+                "auth": "dXNlcjI6cGFzczI="
+            }
+        }
+    }
+    """;
+
+    @Test
+    void testHierarchicalCredentialLookupMostSpecific() throws Exception {
+        Path configFile = tempDir.resolve("hierarchical-config.json");
+        Files.writeString(configFile, SAMPLE_HIERARCHICAL_CONFIG);
+        AuthStore store = AuthStore.newStore(List.of(configFile));
+
+        // Most specific key: my-registry.local/namespace/user/image
+        AuthStore.Credential credential =
+                store.get(ContainerRef.parse("my-registry.local/namespace/user/image:latest"));
+        assertNotNull(credential);
+        assertEquals("user1", credential.username());
+        assertEquals("pass1", credential.password());
+    }
+
+    @Test
+    void testHierarchicalCredentialLookupNamespaceOnly() throws Exception {
+        Path configFile = tempDir.resolve("hierarchical-config.json");
+        Files.writeString(configFile, SAMPLE_HIERARCHICAL_CONFIG);
+        AuthStore store = AuthStore.newStore(List.of(configFile));
+
+        // Credential stored at namespace level: my-registry.local/namespace
+        // Image under that namespace but not exact-matched should fall back to namespace credential
+        AuthStore.Credential credential =
+                store.get(ContainerRef.parse("my-registry.local/namespace/other-image:latest"));
+        assertNotNull(credential);
+        assertEquals("user3", credential.username());
+        assertEquals("pass3", credential.password());
+    }
+
+    @Test
+    void testHierarchicalCredentialLookupFallsBackToRegistry() throws Exception {
+        Path configFile = tempDir.resolve("hierarchical-config.json");
+        Files.writeString(configFile, SAMPLE_HIERARCHICAL_CONFIG);
+        AuthStore store = AuthStore.newStore(List.of(configFile));
+
+        // Different image under the same registry falls back to registry-level credential
+        AuthStore.Credential credential = store.get(ContainerRef.parse("my-registry.local/other/repo:latest"));
+        assertNotNull(credential);
+        assertEquals("user2", credential.username());
+        assertEquals("pass2", credential.password());
+    }
+
+    @Test
+    void testHierarchicalCredentialLookupRegistryOnly() throws Exception {
+        Path configFile = tempDir.resolve("hierarchical-config.json");
+        Files.writeString(configFile, SAMPLE_HIERARCHICAL_CONFIG);
+        AuthStore store = AuthStore.newStore(List.of(configFile));
+
+        // Image without namespace falls back to registry-level credential
+        AuthStore.Credential credential = store.get(ContainerRef.parse("my-registry.local/image:latest"));
+        assertNotNull(credential);
+        assertEquals("user2", credential.username());
+        assertEquals("pass2", credential.password());
+    }
+
+    @Test
+    void testHierarchicalCredentialLookupNoMatch() throws Exception {
+        Path configFile = tempDir.resolve("hierarchical-config.json");
+        Files.writeString(configFile, SAMPLE_HIERARCHICAL_CONFIG);
+        AuthStore store = AuthStore.newStore(List.of(configFile));
+
+        // Unknown registry returns null
+        AuthStore.Credential credential = store.get(ContainerRef.parse("unknown-registry.local/foo/bar:latest"));
+        assertNull(credential);
+    }
+
     @Test
     void testWithoutXdgRuntimeDir() throws Exception {
         new EnvironmentVariables().remove("XDG_RUNTIME_DIR").execute(() -> {