From 7bfbb7b3bdaf55a85d15e9c5c5d25a88bd896b04 Mon Sep 17 00:00:00 2001
From: Tanguy Leroux <tlrx.dev@gmail.com>
Date: Wed, 16 May 2018 16:58:46 +0200
Subject: [PATCH] Fix _cluster/state to always return cluster_uuid

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 880efaff19aa6..861e1200991b1 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 58d6a299bb936..22e71e0a85f49 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 @@ protected void masterOperation(final ClusterStateRequest request, final ClusterS
         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 @@ protected void masterOperation(final ClusterStateRequest request, final ClusterS
                         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) {