From 6e944d9e2128eb7ca6a6b7d44ec911f819eaf5a5 Mon Sep 17 00:00:00 2001
From: Tanguy Leroux <tlrx.dev@gmail.com>
Date: Tue, 1 Sep 2020 17:41:57 +0200
Subject: [PATCH] Throws IndexNotFoundException in TransportGetAction for
 unknown System indices (#61785) (#61791)

The change #57936 introduced a dedicated thread pool for reads in system indices.
It also introduced a potential NPE in the case the index to read in not yet present in
the cluster state. This commit fixes that bug by using the getIndexSafe() instead of
just index() method when retrieving the index's metadata so that an INFE is thrown
if the index does not exist.
---
 .../java/org/elasticsearch/action/get/TransportGetAction.java   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/server/src/main/java/org/elasticsearch/action/get/TransportGetAction.java b/server/src/main/java/org/elasticsearch/action/get/TransportGetAction.java
index b7b361ff550..8dde9e104dd 100644
--- a/server/src/main/java/org/elasticsearch/action/get/TransportGetAction.java
+++ b/server/src/main/java/org/elasticsearch/action/get/TransportGetAction.java
@@ -116,7 +116,7 @@ public class TransportGetAction extends TransportSingleShardAction<GetRequest, G
     @Override
     protected String getExecutor(GetRequest request, ShardId shardId) {
         final ClusterState clusterState = clusterService.state();
-        if (clusterState.metadata().index(shardId.getIndex()).isSystem()) {
+        if (clusterState.metadata().getIndexSafe(shardId.getIndex()).isSystem()) {
             return ThreadPool.Names.SYSTEM_READ;
         } else if (indicesService.indexServiceSafe(shardId.getIndex()).getIndexSettings().isSearchThrottled()) {
             return ThreadPool.Names.SEARCH_THROTTLED;