From 64031865c1368e67036c8155e0dc4217688391d4 Mon Sep 17 00:00:00 2001
From: Lee Hinman <lee@writequit.org>
Date: Mon, 8 Jun 2020 12:49:12 -0600
Subject: [PATCH] Throw exception on duplicate mappings metadata fields

In #57701 we changed mappings merging so that duplicate fields specified in mappings caused an
exception during validation. This change makes the same exception thrown when metadata fields are
duplicated. This will allow us to be strict currently with plans to make the merging more
fine-grained in a later release.
---
 .../cluster/metadata/MetadataCreateIndexService.java   |  6 ++----
 .../cluster/metadata/MetadataIndexTemplateService.java | 10 ++++------
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataCreateIndexService.java b/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataCreateIndexService.java
index 5b1df19dfaaed..4453e8167fa11 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataCreateIndexService.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataCreateIndexService.java
@@ -591,8 +591,7 @@ static Map<String, Map<String, Object>> parseV2Mappings(String mappingsJson, Lis
                 Map<String, Object> innerTemplateNonProperties = new HashMap<>(innerTemplateMapping);
                 Map<String, Object> maybeProperties = (Map<String, Object>) innerTemplateNonProperties.remove("properties");
 
-                XContentHelper.mergeDefaults(innerTemplateNonProperties, nonProperties);
-                nonProperties = innerTemplateNonProperties;
+                nonProperties = mergeFailingOnReplacement(nonProperties, innerTemplateNonProperties);
 
                 if (maybeProperties != null) {
                     properties = mergeFailingOnReplacement(properties, maybeProperties);
@@ -605,8 +604,7 @@ static Map<String, Map<String, Object>> parseV2Mappings(String mappingsJson, Lis
             Map<String, Object> innerRequestNonProperties = new HashMap<>(innerRequestMappings);
             Map<String, Object> maybeRequestProperties = (Map<String, Object>) innerRequestNonProperties.remove("properties");
 
-            XContentHelper.mergeDefaults(innerRequestNonProperties, nonProperties);
-            nonProperties = innerRequestNonProperties;
+            nonProperties = mergeFailingOnReplacement(nonProperties, innerRequestNonProperties);
 
             if (maybeRequestProperties != null) {
                 properties = mergeFailingOnReplacement(properties, maybeRequestProperties);
diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java b/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java
index 5c4d5db655d34..6efa323e5947f 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java
@@ -987,14 +987,12 @@ private static void validateCompositeTemplate(final ClusterState state,
 
                 // Parse mappings to ensure they are valid after being composed
                 List<CompressedXContent> mappings = resolveMappings(stateWithIndex, templateName);
-                final Map<String, Map<String, Object>> finalMappings;
                 try {
+                    Map<String, Map<String, Object>> finalMappings =
+                        MetadataCreateIndexService.parseV2Mappings("{}", mappings, xContentRegistry);
                     MapperService dummyMapperService = tempIndexService.mapperService();
-                    for (CompressedXContent mapping : mappings) {
-                        // TODO: Eventually change this to:
-                        // dummyMapperService.merge(MapperService.SINGLE_MAPPING_NAME, mapping, MergeReason.INDEX_TEMPLATE);
-                        dummyMapperService.merge(MapperService.SINGLE_MAPPING_NAME, mapping, MergeReason.MAPPING_UPDATE);
-                    }
+                        // TODO: Eventually change this to use MergeReason.INDEX_TEMPLATE
+                        dummyMapperService.merge(finalMappings, MergeReason.MAPPING_UPDATE);
                 } catch (Exception e) {
                     throw new IllegalArgumentException("invalid composite mappings for [" + templateName + "]", e);
                 }