From 395636574ae2444779c5ea45b1edef8e5538f9a4 Mon Sep 17 00:00:00 2001
From: Srikanth Padakanti <srikanth29.9@gmail.com>
Date: Tue, 23 Apr 2024 01:24:11 -0500
Subject: [PATCH] Improve error messages for `_stats` with closed indices 
 (#13012) (#13338)

---
 CHANGELOG.md                                  |  3 ++-
 .../index/rankeval/RankEvalRequestIT.java     |  2 +-
 .../metadata/IndexNameExpressionResolver.java |  8 +++++++-
 .../IndexNameExpressionResolverTests.java     | 19 +++++++++++++++++++
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a36c93550043..07f6d949dedc5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,7 +56,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix issue with feature flags where default value may not be honored ([#12849](https://github.com/opensearch-project/OpenSearch/pull/12849))
 - Enabled mockTelemetryPlugin for IT and fixed OOM issues ([#13054](https://github.com/opensearch-project/OpenSearch/pull/13054))
 - Fix implement mark() and markSupported() in class FilterStreamInput ([#13098](https://github.com/opensearch-project/OpenSearch/pull/13098))
-- Fix snapshot _status API to return correct status for partial snapshots ([#13260](https://github.com/opensearch-project/OpenSearch/pull/13260))
+- Fix snapshot _status API to return correct status for partial snapshots ([#12812](https://github.com/opensearch-project/OpenSearch/pull/12812))
+- Improve the error messages for _stats with closed indices ([#13012](https://github.com/opensearch-project/OpenSearch/pull/13012))
 - Ignore BaseRestHandler unconsumed content check as it's always consumed. ([#13290](https://github.com/opensearch-project/OpenSearch/pull/13290))
 
 ### Security
diff --git a/modules/rank-eval/src/internalClusterTest/java/org/opensearch/index/rankeval/RankEvalRequestIT.java b/modules/rank-eval/src/internalClusterTest/java/org/opensearch/index/rankeval/RankEvalRequestIT.java
index 2abbc8b23598c..35ddde7b368f8 100644
--- a/modules/rank-eval/src/internalClusterTest/java/org/opensearch/index/rankeval/RankEvalRequestIT.java
+++ b/modules/rank-eval/src/internalClusterTest/java/org/opensearch/index/rankeval/RankEvalRequestIT.java
@@ -345,7 +345,7 @@ public void testIndicesOptions() {
         request.indicesOptions(IndicesOptions.fromParameters("closed", null, null, "false", SearchRequest.DEFAULT_INDICES_OPTIONS));
         response = client().execute(RankEvalAction.INSTANCE, request).actionGet();
         assertEquals(1, response.getFailures().size());
-        assertThat(response.getFailures().get("amsterdam_query"), instanceOf(IndexClosedException.class));
+        assertThat(response.getFailures().get("amsterdam_query"), instanceOf(IllegalArgumentException.class));
 
         // test allow_no_indices
         request = new RankEvalRequest(task, new String[] { "bad*" });
diff --git a/server/src/main/java/org/opensearch/cluster/metadata/IndexNameExpressionResolver.java b/server/src/main/java/org/opensearch/cluster/metadata/IndexNameExpressionResolver.java
index 86961010c77d6..f7663e5509112 100644
--- a/server/src/main/java/org/opensearch/cluster/metadata/IndexNameExpressionResolver.java
+++ b/server/src/main/java/org/opensearch/cluster/metadata/IndexNameExpressionResolver.java
@@ -383,7 +383,13 @@ private void checkSystemIndexAccess(Context context, Metadata metadata, Set<Inde
     private static boolean shouldTrackConcreteIndex(Context context, IndicesOptions options, IndexMetadata index) {
         if (index.getState() == IndexMetadata.State.CLOSE) {
             if (options.forbidClosedIndices() && options.ignoreUnavailable() == false) {
-                throw new IndexClosedException(index.getIndex());
+                if (options.expandWildcardsClosed() == true && options.getExpandWildcards().size() == 1) {
+                    throw new IllegalArgumentException(
+                        "To expand [" + index.getState() + "] wildcard, please set forbid_closed_indices to `false`"
+                    );
+                } else {
+                    throw new IndexClosedException(index.getIndex());
+                }
             } else {
                 return options.forbidClosedIndices() == false && addIndex(index, context);
             }
diff --git a/server/src/test/java/org/opensearch/cluster/metadata/IndexNameExpressionResolverTests.java b/server/src/test/java/org/opensearch/cluster/metadata/IndexNameExpressionResolverTests.java
index 51696ca599d02..fda2f411b1994 100644
--- a/server/src/test/java/org/opensearch/cluster/metadata/IndexNameExpressionResolverTests.java
+++ b/server/src/test/java/org/opensearch/cluster/metadata/IndexNameExpressionResolverTests.java
@@ -352,6 +352,25 @@ public void testIndexOptionsWildcardExpansion() {
         assertEquals(1, results.length);
         assertThat(results, arrayContainingInAnyOrder(".hidden-closed"));
 
+        options = IndicesOptions.fromOptions(false, true, false, true, false, false, false, false);
+        context = new IndexNameExpressionResolver.Context(state, options, false);
+
+        results = indexNameExpressionResolver.concreteIndexNames(context, "foo*");
+        assertEquals(1, results.length);
+        assertEquals("foo", results[0]);
+
+        try {
+            options = IndicesOptions.fromOptions(false, true, false, true, false, true, false, false);
+            context = new IndexNameExpressionResolver.Context(state, options, false);
+
+            results = indexNameExpressionResolver.concreteIndexNames(context, "foo*");
+            assertEquals(1, results.length);
+            assertEquals("foo", results[0]);
+        } catch (IllegalArgumentException iae) {
+            String expectedMessage = "To expand [CLOSE] wildcard, please set forbid_closed_indices to `false`";
+            assertEquals(expectedMessage, iae.getMessage());
+        }
+
         // Only open
         options = IndicesOptions.fromOptions(false, true, true, false, false);
         context = new IndexNameExpressionResolver.Context(state, options, false);