Changed http code on create index API with bad input raising NotXContentException to 400

CHANGELOG.md

@@ -54,6 +54,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Use ReplicationFailedException instead of OpensearchException in ReplicationTarget ([#4725](https://github.com/opensearch-project/OpenSearch/pull/4725))
 - Migrate client transports to Apache HttpClient / Core 5.x ([#4459](https://github.com/opensearch-project/OpenSearch/pull/4459))
 - Support remote translog transfer for request level durability([#4480](https://github.com/opensearch-project/OpenSearch/pull/4480))
+- Changed http code on create index API with bad input raising NotXContentException from 500 to 400 ([#4773](https://github.com/opensearch-project/OpenSearch/pull/4773))
 
 ### Deprecated
 

server/src/main/java/org/opensearch/ExceptionsHelper.java

@@ -40,6 +40,7 @@
 import org.apache.lucene.index.IndexFormatTooOldException;
 import org.opensearch.action.ShardOperationFailedException;
 import org.opensearch.common.Nullable;
+import org.opensearch.common.compress.NotXContentException;
 import org.opensearch.common.util.concurrent.OpenSearchRejectedExecutionException;
 import org.opensearch.index.Index;
 import org.opensearch.rest.RestStatus;
@@ -94,6 +95,8 @@ public static RestStatus status(Throwable t) {
                 return RestStatus.BAD_REQUEST;
             } else if (t instanceof OpenSearchRejectedExecutionException) {
                 return RestStatus.TOO_MANY_REQUESTS;
+            } else if (t instanceof NotXContentException) {
+                return RestStatus.BAD_REQUEST;
             }
         }
         return RestStatus.INTERNAL_SERVER_ERROR;

server/src/test/java/org/opensearch/rest/RestControllerTests.java

@@ -53,6 +53,7 @@
 import org.opensearch.http.HttpServerTransport;
 import org.opensearch.http.HttpStats;
 import org.opensearch.indices.breaker.HierarchyCircuitBreakerService;
+import org.opensearch.rest.action.admin.indices.RestCreateIndexAction;
 import org.opensearch.test.OpenSearchTestCase;
 import org.opensearch.test.client.NoOpNodeClient;
 import org.opensearch.test.rest.FakeRestRequest;
@@ -562,6 +563,20 @@ public void testHandleBadRequestWithHtmlSpecialCharsInUri() {
         assertThat(channel.getRestResponse().content().utf8ToString(), containsString("invalid uri has been requested"));
     }
 
+    public void testHandleBadInputWithCreateIndex() {
+        final FakeRestRequest fakeRestRequest = new FakeRestRequest.Builder(NamedXContentRegistry.EMPTY).withPath("/foo")
+            .withMethod(RestRequest.Method.PUT)
+            .withContent(new BytesArray("ddd"), XContentType.JSON)
+            .build();
+        final AssertingChannel channel = new AssertingChannel(fakeRestRequest, true, RestStatus.BAD_REQUEST);
+        restController.registerHandler(RestRequest.Method.PUT, "/foo", new RestCreateIndexAction());
+        restController.dispatchRequest(fakeRestRequest, channel, client.threadPool().getThreadContext());
+        assertEquals(
+            channel.getRestResponse().content().utf8ToString(),
+            "{\"error\":{\"root_cause\":[{\"type\":\"not_x_content_exception\",\"reason\":\"Compressor detection can only be called on some xcontent bytes or compressed xcontent bytes\"}],\"type\":\"not_x_content_exception\",\"reason\":\"Compressor detection can only be called on some xcontent bytes or compressed xcontent bytes\"},\"status\":400}"
+        );
+    }
+
     public void testDispatchUnsupportedHttpMethod() {
         final boolean hasContent = randomBoolean();
         final RestRequest request = RestRequest.request(xContentRegistry(), new HttpRequest() {