adding yaml rest test for get settings

Author: masseyke

modules/data-streams/src/yamlRestTest/resources/rest-api-spec/test/data_stream/240_data_stream_settings.yml

@@ -1,5 +1,5 @@
 setup:
-  - skip: 
+  - skip:
       features: allowed_warnings
 
 ---
@@ -30,6 +30,22 @@ setup:
         index: "my-data-stream-1"
         wait_for_status: green
 
+  - do:
+      indices.get_data_stream_settings:
+        name: my-data-stream-1
+  - match: { data_streams.0.name: my-data-stream-1 }
+  - match: { data_streams.0.settings: {} }
+  - match: { data_streams.0.effective_settings.index.number_of_shards: null }
+  - match: { data_streams.0.effective_settings.index.number_of_replicas: "0" }
+  - match: { data_streams.0.effective_settings.index.lifecycle.name: "my-policy" }
+
+  - do:
+      indices.get_data_stream:
+        name: my-data-stream-1
+  - match: { data_streams.0.name: my-data-stream-1 }
+  - match: { data_streams.0.settings: {} }
+  - match: { data_streams.0.effective_settings: null }
+
   - do:
       indices.put_data_stream_settings:
         name: my-data-stream-1
@@ -45,6 +61,22 @@ setup:
   - match: { data_streams.0.effective_settings.index.number_of_replicas: "0" }
   - match: { data_streams.0.effective_settings.index.lifecycle.name: "my-policy" }
 
+  - do:
+      indices.get_data_stream_settings:
+        name: my-data-stream-1
+  - match: { data_streams.0.name: my-data-stream-1 }
+  - match: { data_streams.0.settings.index.number_of_shards: "2" }
+  - match: { data_streams.0.effective_settings.index.number_of_shards: "2" }
+  - match: { data_streams.0.effective_settings.index.number_of_replicas: "0" }
+  - match: { data_streams.0.effective_settings.index.lifecycle.name: "my-policy" }
+
+  - do:
+      indices.get_data_stream:
+        name: my-data-stream-1
+  - match: { data_streams.0.name: my-data-stream-1 }
+  - match: { data_streams.0.settings.index.number_of_shards: "2" }
+  - match: { data_streams.0.effective_settings: null }
+
 ---
 "Test invalid settings":
   - do:

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

@@ -0,0 +1,39 @@
+{
+  "indices.get_data_stream_settings":{
+    "documentation":{
+      "url":"https://www.elastic.co/guide/en/elasticsearch/reference/master/data-streams.html",
+      "description":"Gets a data stream's settings"
+    },
+    "stability":"stable",
+    "visibility":"public",
+    "headers":{
+      "accept": [ "application/json"]
+    },
+    "url":{
+      "paths":[
+        {
+          "path":"/_data_stream/{name}/_settings",
+          "methods":[
+            "GET"
+          ],
+          "parts":{
+            "name":{
+              "type":"string",
+              "description":"The name of the data stream or data stream pattern"
+            }
+          }
+        }
+      ]
+    },
+    "params":{
+      "timeout":{
+        "type":"time",
+        "description":"Specify timeout for acknowledging the cluster state update"
+      },
+      "master_timeout":{
+        "type":"time",
+        "description":"Specify timeout for connection to master"
+      }
+    }
+  }
+}