Ignore system index access errors in YAML test index cleanup method

Author: lukewhiting

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -26,6 +26,8 @@
 import org.apache.http.ssl.SSLContextBuilder;
 import org.apache.http.ssl.SSLContexts;
 import org.apache.http.util.EntityUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.elasticsearch.Build;
 import org.elasticsearch.TransportVersion;
 import org.elasticsearch.TransportVersions;
@@ -160,6 +162,8 @@ public abstract class ESRestTestCase extends ESTestCase {
 
     private static final Pattern SEMANTIC_VERSION_PATTERN = Pattern.compile("^(\\d+\\.\\d+\\.\\d+)\\D?.*");
 
+    private static final Logger SUITE_LOGGER = LogManager.getLogger(ESRestTestCase.class);
+
     /**
      * Convert the entity from a {@link Response} into a map of maps.
      * Consumes the underlying HttpEntity, releasing any resources it may be holding.
@@ -1131,6 +1135,19 @@ protected static void wipeAllIndices(boolean preserveSecurityIndices) throws IOE
             }
             final Request deleteRequest = new Request("DELETE", Strings.collectionToCommaDelimitedString(indexPatterns));
             deleteRequest.addParameter("expand_wildcards", "open,closed,hidden");
+
+            // If system index warning, ignore but log
+            deleteRequest.setOptions(RequestOptions.DEFAULT.toBuilder().setWarningsHandler(warnings -> {
+                for (String warning : warnings) {
+                    if (warning.startsWith("this request accesses system indices:")) {
+                        SUITE_LOGGER.warn("Ignoring system index access warning during test cleanup: {}", warning);
+                    } else {
+                        return true;
+                    }
+                }
+                return false;
+            }));
+
             final Response response = adminClient().performRequest(deleteRequest);
             try (InputStream is = response.getEntity().getContent()) {
                 assertTrue((boolean) XContentHelper.convertToMap(XContentType.JSON.xContent(), is, true).get("acknowledged"));