TSDB: Do not allow index splits for time series indices (#81125)

Index _split operation may have some issues with time series indices, as
the splits must respect and adjust the time boundaries.

This PR forbids users to execute the split operation on time series indices,
until we revisit this approach in the future.

Author: csoulios

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/tsdb/80_index_resize.yml

@@ -1,7 +1,7 @@
 setup:
   - skip:
-      version: " - 7.99.99"
-      reason: introduced in 8.0.0
+      version: " - 8.00.99"
+      reason: introduced in 8.1.0
       features: "arbitrary_key"
 
   # Force allocating all shards to a single node so that we can shrink later.
@@ -82,11 +82,11 @@ setup:
 ---
 split:
   - skip:
-      version: all
-      reason: shard splitting doesn't work yet
-      features: "arbitrary_key"
+      version: " - 8.00.99"
+      reason: index-split check introduced in 8.1.0
 
   - do:
+      catch: /index-split is not supported because the destination index \[test\] is in time series mode/
       indices.split:
         index: test
         target: test_split
@@ -95,19 +95,6 @@ split:
             index.number_of_replicas: 0
             index.number_of_shards: 6
 
-  - do:
-      search:
-        index: test_split
-        body:
-          fields:
-            - field: _tsid
-          query:
-            query_string:
-              query: '+@timestamp:"2021-04-28T18:51:04.467Z" +k8s.pod.name:cat'
-
-  - match: {hits.total.value: 1}
-  - match: {hits.hits.0.fields._tsid: [{k8s.pod.uid: 947e4ced-1786-4e53-9e0c-5c447e959507, metricset: pod}]}
-
 ---
 shrink:
   - skip:

server/src/main/java/org/elasticsearch/action/admin/indices/shrink/TransportResizeAction.java

@@ -27,6 +27,7 @@
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.metadata.MetadataCreateIndexService;
+import org.elasticsearch.cluster.routing.IndexRouting;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
@@ -124,6 +125,11 @@ protected void masterOperation(
             return;
         }
 
+        // Index splits are not allowed for time-series indices
+        if (resizeRequest.getResizeType() == ResizeType.SPLIT) {
+            IndexRouting.fromIndexMetadata(sourceMetadata).checkIndexSplitAllowed();
+        }
+
         IndicesStatsRequestBuilder statsRequestBuilder = client.admin()
             .indices()
             .prepareStats(sourceIndex)

server/src/main/java/org/elasticsearch/cluster/routing/IndexRouting.java

@@ -110,6 +110,12 @@ private static int effectiveRoutingToHash(String effectiveRouting) {
         return Murmur3HashFunction.hash(effectiveRouting);
     }
 
+    /**
+     * Check if the _split index operation is allowed for an index
+     * @throws IllegalArgumentException if the operation is not allowed
+     */
+    public void checkIndexSplitAllowed() {}
+
     private abstract static class IdAndRoutingOnly extends IndexRouting {
         private final boolean routingRequired;
 
@@ -295,6 +301,11 @@ public int getShard(String id, @Nullable String routing) {
             throw new IllegalArgumentException(error("get"));
         }
 
+        @Override
+        public void checkIndexSplitAllowed() {
+            throw new IllegalArgumentException(error("index-split"));
+        }
+
         @Override
         public void collectSearchShards(String routing, IntConsumer consumer) {
             throw new IllegalArgumentException(error("searching with a specified routing"));