Add simulate template composition API _index_template/_simulate_index/{name}

client/rest-high-level/src/test/java/org/elasticsearch/client/RestHighLevelClientTests.java

@@ -861,6 +861,7 @@ public void testApiNamingConventions() throws Exception {
             "indices.create_data_stream",
             "indices.get_data_streams",
             "indices.delete_data_stream",
+            "indices.simulate_index_template"
         };
         //These API are not required for high-level client feature completeness
         String[] notRequiredApi = new String[] {

rest-api-spec/src/main/resources/rest-api-spec/api/indices.simulate_index_template.json

@@ -0,0 +1,35 @@
+{
+  "indices.simulate_index_template":{
+    "documentation":{
+      "url":"https://www.elastic.co/guide/en/elasticsearch/reference/master/indices-templates.html",
+      "description": "Simulate matching the given index name against the index templates in the system"
+    },
+    "stability":"stable",
+    "url":{
+      "paths":[
+        {
+          "path":"/_index_template/_simulate_index/{name}",
+          "methods":[
+            "POST"
+          ],
+          "parts":{
+            "name":{
+              "type":"string",
+              "description":"The name of the index (it will have to be a concrete index name)"
+            }
+          }
+        }
+      ]
+    },
+    "params":{
+      "master_timeout":{
+        "type":"time",
+        "description":"Specify timeout for connection to master"
+      }
+    },
+    "body":{
+      "description":"New index template definition, which will be included in the simulation, as if it already exists in the system",
+      "required":false
+    }
+  }
+}

rest-api-spec/src/main/resources/rest-api-spec/test/indices.post_simulate_index_template/10_basic.yml

@@ -0,0 +1,140 @@
+---
+"Simulate index template without new template in the body":
+  - skip:
+      version: " - 7.99.99"
+      reason: "simulate index template API has not been backported"
+      features: allowed_warnings
+
+  - do:
+      allowed_warnings:
+        - "index template [test] has index patterns [te*] matching patterns from existing older templates [global] with patterns (global => [*]); this template [test] will take precedence during new index creation"
+      indices.put_index_template:
+        name: test
+        body:
+          index_patterns: te*
+          template:
+            settings:
+              number_of_shards:   1
+              number_of_replicas: 0
+            mappings:
+              properties:
+                field:
+                  type: keyword
+
+  - do:
+      indices.simulate_index_template:
+        name: test
+
+  - match: {template.settings.index.number_of_shards: "1"}
+  - match: {template.settings.index.number_of_replicas: "0"}
+  - match: {template.mappings._doc.properties.field.type: "keyword"}
+  - match: {overlapping_v1_templates: {}}
+
+---
+"Simulate index template specifying a new template":
+  - skip:
+      version: " - 7.99.99"
+      reason: "simulate index template API has not been backported"
+      features: allowed_warnings
+
+  - do:
+      allowed_warnings:
+        - "index template [test] has index patterns [te*] matching patterns from existing older templates [global] with patterns (global => [*]); this template [test] will take precedence during new index creation"
+      indices.put_index_template:
+        name: test
+        body:
+          index_patterns: te*
+          priority: 10
+          template:
+            settings:
+              number_of_shards:   1
+              number_of_replicas: 0
+            mappings:
+              properties:
+                field:
+                  type: keyword
+
+  - do:
+      indices.simulate_index_template:
+        name: test
+        body:
+          index_patterns: te*
+          priority: 15
+          template:
+            settings:
+              index.blocks.write: true
+
+  - match: {template.settings.index.blocks.write: "true"}
+  - match: {overlapping_v1_templates: {}}
+
+---
+"Simulate index template with index not matching any template":
+  - skip:
+      version: " - 7.99.99"
+      reason: "simulate index template API has not been backported"
+      features: allowed_warnings
+
+  - do:
+      allowed_warnings:
+        - "index template [test] has index patterns [te*] matching patterns from existing older templates [global] with patterns (global => [*]); this template [test] will take precedence during new index creation"
+      indices.put_index_template:
+        name: test
+        body:
+          index_patterns: te*
+          priority: 10
+          template:
+            settings:
+              number_of_shards:   1
+              number_of_replicas: 0
+            mappings:
+              properties:
+                field:
+                  type: keyword
+
+  - do:
+      indices.simulate_index_template:
+        name: will_not_match
+
+  - match: {body: null}
+
+---
+"Simulate index matches overlapping V1 and V2 templates":
+  - skip:
+      version: " - 7.99.99"
+      reason: "simulate index template API has not been backported"
+      features: allowed_warnings
+
+  - do:
+      indices.put_template:
+        name: v1_template
+        body:
+          index_patterns: [t*, t1*]
+          settings:
+            number_of_shards:   5
+
+  - do:
+      allowed_warnings:
+        - "index template [test] has index patterns [te*] matching patterns from existing older templates [v1_template] with patterns
+        (v1_template => [t*, t1*]); this template [test] will take precedence during new index creation"
+      indices.put_index_template:
+        name: test
+        body:
+          index_patterns: te*
+          priority: 10
+          template:
+            settings:
+              number_of_shards:   1
+              number_of_replicas: 0
+            mappings:
+              properties:
+                field:
+                  type: keyword
+
+  - do:
+      indices.simulate_index_template:
+        name: test
+
+  - match: {template.settings.index.number_of_shards: "1"}
+  - match: {template.settings.index.number_of_replicas: "0"}
+  - match: {template.mappings._doc.properties.field.type: "keyword"}
+  - match: {overlapping_v1_templates: {v1_template: ["t*", "t1*"]}}

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -28,9 +28,6 @@
 import org.elasticsearch.action.admin.cluster.configuration.ClearVotingConfigExclusionsAction;
 import org.elasticsearch.action.admin.cluster.configuration.TransportAddVotingConfigExclusionsAction;
 import org.elasticsearch.action.admin.cluster.configuration.TransportClearVotingConfigExclusionsAction;
-import org.elasticsearch.action.admin.indices.datastream.DeleteDataStreamAction;
-import org.elasticsearch.action.admin.indices.datastream.GetDataStreamsAction;
-import org.elasticsearch.action.admin.indices.datastream.CreateDataStreamAction;
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthAction;
 import org.elasticsearch.action.admin.cluster.health.TransportClusterHealthAction;
 import org.elasticsearch.action.admin.cluster.node.hotthreads.NodesHotThreadsAction;
@@ -108,6 +105,9 @@
 import org.elasticsearch.action.admin.indices.close.TransportVerifyShardBeforeCloseAction;
 import org.elasticsearch.action.admin.indices.create.CreateIndexAction;
 import org.elasticsearch.action.admin.indices.create.TransportCreateIndexAction;
+import org.elasticsearch.action.admin.indices.datastream.CreateDataStreamAction;
+import org.elasticsearch.action.admin.indices.datastream.DeleteDataStreamAction;
+import org.elasticsearch.action.admin.indices.datastream.GetDataStreamsAction;
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexAction;
 import org.elasticsearch.action.admin.indices.delete.TransportDeleteIndexAction;
 import org.elasticsearch.action.admin.indices.flush.FlushAction;
@@ -158,6 +158,8 @@
 import org.elasticsearch.action.admin.indices.template.get.TransportGetComponentTemplateAction;
 import org.elasticsearch.action.admin.indices.template.get.TransportGetIndexTemplateV2Action;
 import org.elasticsearch.action.admin.indices.template.get.TransportGetIndexTemplatesAction;
+import org.elasticsearch.action.admin.indices.template.post.SimulateIndexTemplateAction;
+import org.elasticsearch.action.admin.indices.template.post.TransportSimulateIndexTemplateAction;
 import org.elasticsearch.action.admin.indices.template.put.PutComponentTemplateAction;
 import org.elasticsearch.action.admin.indices.template.put.PutIndexTemplateAction;
 import org.elasticsearch.action.admin.indices.template.put.PutIndexTemplateV2Action;
@@ -260,11 +262,9 @@
 import org.elasticsearch.rest.action.admin.cluster.RestClusterStatsAction;
 import org.elasticsearch.rest.action.admin.cluster.RestClusterUpdateSettingsAction;
 import org.elasticsearch.rest.action.admin.cluster.RestCreateSnapshotAction;
-import org.elasticsearch.rest.action.admin.indices.RestDeleteDataStreamAction;
 import org.elasticsearch.rest.action.admin.cluster.RestDeleteRepositoryAction;
 import org.elasticsearch.rest.action.admin.cluster.RestDeleteSnapshotAction;
 import org.elasticsearch.rest.action.admin.cluster.RestDeleteStoredScriptAction;
-import org.elasticsearch.rest.action.admin.indices.RestGetDataStreamsAction;
 import org.elasticsearch.rest.action.admin.cluster.RestGetRepositoriesAction;
 import org.elasticsearch.rest.action.admin.cluster.RestGetScriptContextAction;
 import org.elasticsearch.rest.action.admin.cluster.RestGetScriptLanguageAction;
@@ -277,7 +277,6 @@
 import org.elasticsearch.rest.action.admin.cluster.RestNodesStatsAction;
 import org.elasticsearch.rest.action.admin.cluster.RestNodesUsageAction;
 import org.elasticsearch.rest.action.admin.cluster.RestPendingClusterTasksAction;
-import org.elasticsearch.rest.action.admin.indices.RestCreateDataStreamAction;
 import org.elasticsearch.rest.action.admin.cluster.RestPutRepositoryAction;
 import org.elasticsearch.rest.action.admin.cluster.RestPutStoredScriptAction;
 import org.elasticsearch.rest.action.admin.cluster.RestReloadSecureSettingsAction;
@@ -288,15 +287,18 @@
 import org.elasticsearch.rest.action.admin.indices.RestAnalyzeAction;
 import org.elasticsearch.rest.action.admin.indices.RestClearIndicesCacheAction;
 import org.elasticsearch.rest.action.admin.indices.RestCloseIndexAction;
+import org.elasticsearch.rest.action.admin.indices.RestCreateDataStreamAction;
 import org.elasticsearch.rest.action.admin.indices.RestCreateIndexAction;
 import org.elasticsearch.rest.action.admin.indices.RestDeleteComponentTemplateAction;
+import org.elasticsearch.rest.action.admin.indices.RestDeleteDataStreamAction;
 import org.elasticsearch.rest.action.admin.indices.RestDeleteIndexAction;
 import org.elasticsearch.rest.action.admin.indices.RestDeleteIndexTemplateAction;
 import org.elasticsearch.rest.action.admin.indices.RestDeleteIndexTemplateV2Action;
 import org.elasticsearch.rest.action.admin.indices.RestFlushAction;
 import org.elasticsearch.rest.action.admin.indices.RestForceMergeAction;
 import org.elasticsearch.rest.action.admin.indices.RestGetAliasesAction;
 import org.elasticsearch.rest.action.admin.indices.RestGetComponentTemplateAction;
+import org.elasticsearch.rest.action.admin.indices.RestGetDataStreamsAction;
 import org.elasticsearch.rest.action.admin.indices.RestGetFieldMappingAction;
 import org.elasticsearch.rest.action.admin.indices.RestGetIndexTemplateAction;
 import org.elasticsearch.rest.action.admin.indices.RestGetIndexTemplateV2Action;
@@ -310,6 +312,7 @@
 import org.elasticsearch.rest.action.admin.indices.RestIndicesShardStoresAction;
 import org.elasticsearch.rest.action.admin.indices.RestIndicesStatsAction;
 import org.elasticsearch.rest.action.admin.indices.RestOpenIndexAction;
+import org.elasticsearch.rest.action.admin.indices.RestSimulateIndexTemplateAction;
 import org.elasticsearch.rest.action.admin.indices.RestPutComponentTemplateAction;
 import org.elasticsearch.rest.action.admin.indices.RestPutIndexTemplateAction;
 import org.elasticsearch.rest.action.admin.indices.RestPutIndexTemplateV2Action;
@@ -550,6 +553,7 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
             actions.register(PutIndexTemplateV2Action.INSTANCE, TransportPutIndexTemplateV2Action.class);
             actions.register(GetIndexTemplateV2Action.INSTANCE, TransportGetIndexTemplateV2Action.class);
             actions.register(DeleteIndexTemplateV2Action.INSTANCE, TransportDeleteIndexTemplateV2Action.class);
+            actions.register(SimulateIndexTemplateAction.INSTANCE, TransportSimulateIndexTemplateAction.class);
         }
         actions.register(ValidateQueryAction.INSTANCE, TransportValidateQueryAction.class);
         actions.register(RefreshAction.INSTANCE, TransportRefreshAction.class);
@@ -700,6 +704,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
             registerHandler.accept(new RestPutIndexTemplateV2Action());
             registerHandler.accept(new RestGetIndexTemplateV2Action());
             registerHandler.accept(new RestDeleteIndexTemplateV2Action());
+            registerHandler.accept(new RestSimulateIndexTemplateAction());
         }
 
         registerHandler.accept(new RestPutMappingAction());

server/src/main/java/org/elasticsearch/action/admin/indices/template/post/SimulateIndexTemplateAction.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.action.admin.indices.template.post;
+
+import org.elasticsearch.action.ActionType;
+
+public class SimulateIndexTemplateAction extends ActionType<SimulateIndexTemplateResponse> {
+
+    public static final SimulateIndexTemplateAction INSTANCE = new SimulateIndexTemplateAction();
+    public static final String NAME = "indices:admin/index_template/simulate_index/post";
+
+    private SimulateIndexTemplateAction() {
+        super(NAME, SimulateIndexTemplateResponse::new);
+    }
+
+}