From 2ac1f9fe89f70e5a3eed084e25504102498763b3 Mon Sep 17 00:00:00 2001
From: Tanguy Leroux <tlrx.dev@gmail.com>
Date: Thu, 17 May 2018 10:58:25 +0200
Subject: [PATCH] Fix _cluster/state to always return cluster_uuid (#30656)

Since #30143, the Cluster State API should always returns the current
cluster_uuid in the response body, regardless of the metrics filters.

This is not exactly true as it is returned only if metadata metrics and
no specific indices are requested.

This commit fixes the behavior to always return the cluster_uuid and
add new test.
---
 .../test/cluster.state/20_filtering.yml       | 18 +++++++++++++++---
 .../state/TransportClusterStateAction.java    | 19 +++++++++----------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/rest-api-spec/src/main/resources/rest-api-spec/test/cluster.state/20_filtering.yml b/rest-api-spec/src/main/resources/rest-api-spec/test/cluster.state/20_filtering.yml
index 880efaff19a..861e1200991 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/test/cluster.state/20_filtering.yml
+++ b/rest-api-spec/src/main/resources/rest-api-spec/test/cluster.state/20_filtering.yml
@@ -163,12 +163,24 @@ setup:
       version:  " - 6.3.99"
       reason:   "cluster state including cluster_uuid at the top level is new in v6.4.0 and higher"
 
+  # Get the current cluster_uuid
+  - do:
+      cluster.state: {}
+  - set: { metadata.cluster_uuid : cluster_uuid }
+
   - do:
       cluster.state:
-        metric: [ master_node, version, metadata ]
+        metric: [ master_node, version ]
 
-  - is_true: cluster_uuid
+  - match: { cluster_uuid: $cluster_uuid }
   - is_true: master_node
   - is_true: version
   - is_true: state_uuid
-  - is_true: metadata
+
+  - do:
+      cluster.state:
+        metric: [ routing_table ]
+        index: testidx
+
+  - match: { cluster_uuid: $cluster_uuid }
+  - is_true: routing_table
diff --git a/server/src/main/java/org/elasticsearch/action/admin/cluster/state/TransportClusterStateAction.java b/server/src/main/java/org/elasticsearch/action/admin/cluster/state/TransportClusterStateAction.java
index 58d6a299bb9..22e71e0a85f 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/cluster/state/TransportClusterStateAction.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/cluster/state/TransportClusterStateAction.java
@@ -98,14 +98,11 @@ public class TransportClusterStateAction extends TransportMasterNodeReadAction<C
         if (request.blocks()) {
             builder.blocks(currentState.blocks());
         }
-        if (request.metaData()) {
-            MetaData.Builder mdBuilder;
-            if (request.indices().length == 0) {
-                mdBuilder = MetaData.builder(currentState.metaData());
-            } else {
-                mdBuilder = MetaData.builder();
-            }
 
+        MetaData.Builder mdBuilder = MetaData.builder();
+        mdBuilder.clusterUUID(currentState.metaData().clusterUUID());
+
+        if (request.metaData()) {
             if (request.indices().length > 0) {
                 String[] indices = indexNameExpressionResolver.concreteIndexNames(currentState, request);
                 for (String filteredIndex : indices) {
@@ -114,17 +111,19 @@ public class TransportClusterStateAction extends TransportMasterNodeReadAction<C
                         mdBuilder.put(indexMetaData, false);
                     }
                 }
+            } else {
+                mdBuilder = MetaData.builder(currentState.metaData());
             }
 
             // Filter our metadata that shouldn't be returned by API
-            for(ObjectObjectCursor<String, Custom> custom :  currentState.metaData().customs()) {
+            for(ObjectObjectCursor<String, Custom> custom : currentState.metaData().customs()) {
                 if(!custom.value.context().contains(MetaData.XContentContext.API)) {
                     mdBuilder.removeCustom(custom.key);
                 }
             }
-
-            builder.metaData(mdBuilder);
         }
+        builder.metaData(mdBuilder);
+
         if (request.customs()) {
             for (ObjectObjectCursor<String, ClusterState.Custom> custom : currentState.customs()) {
                 if (custom.value.isPrivate() == false) {