Replace 210_logs_custom_mappings.yml with java rest test (elastic#99734…

…) (elastic#100006)

The test fails because the logs template is not initialised in time for
the test to retrieve it. To fix this we convert the yaml test to java
rest test, this allows us to wait until the logs has been initialised
before we continue with the test steps.

Fixes: elastic#99734

modules/data-streams/src/javaRestTest/java/org/elasticsearch/datastreams/LogsDataStreamIT.java

@@ -101,6 +101,87 @@ public void testDefaultLogsSettingAndMapping() throws Exception {
         }
     }
 
+    @SuppressWarnings("unchecked")
+    public void testCustomMapping() throws Exception {
+        RestClient client = client();
+        waitForLogs(client);
+
+        {
+            Request request = new Request("POST", "/_component_template/logs@custom");
+            request.setJsonEntity("""
+                {
+                  "template": {
+                    "settings": {
+                      "index": {
+                        "query": {
+                          "default_field": ["custom-message"]
+                        }
+                      }
+                    },
+                    "mappings": {
+                      "properties": {
+                        "numeric_field": {
+                          "type": "integer"
+                        },
+                        "socket": {
+                          "properties": {
+                            "ip": {
+                              "type": "keyword"
+                            }
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+                """);
+            assertOK(client.performRequest(request));
+        }
+
+        String dataStreamName = "logs-generic-default";
+        createDataStream(client, dataStreamName);
+        String backingIndex = getWriteBackingIndex(client, dataStreamName);
+
+        // Verify that the custom settings.index.query.default_field overrides the default query field - "message"
+        Map<String, Object> settings = getSettings(client, backingIndex);
+        assertThat(settings.get("index.query.default_field"), is(List.of("custom-message")));
+
+        // Verify that the new field from the custom component template is applied
+        putMapping(client, backingIndex);
+        Map<String, Object> mappingProperties = getMappingProperties(client, backingIndex);
+        assertThat(((Map<String, Object>) mappingProperties.get("numeric_field")).get("type"), equalTo("integer"));
+        assertThat(
+            ((Map<String, Object>) mappingProperties.get("socket")).get("properties"),
+            equalTo(Map.of("ip", Map.of("type", "keyword")))
+        );
+
+        // Insert valid doc and verify successful indexing
+        {
+            indexDoc(client, dataStreamName, """
+                {
+                  "test": "doc-with-ip",
+                  "socket": {
+                    "ip": "127.0.0.1"
+                  }
+                }
+                """);
+            List<Object> results = searchDocs(client, dataStreamName, """
+                {
+                  "query": {
+                    "term": {
+                      "test": {
+                        "value": "doc-with-ip"
+                      }
+                    }
+                  },
+                  "fields": ["socket.ip"]
+                }
+                """);
+            Map<String, Object> fields = ((Map<String, Map<String, Object>>) results.get(0)).get("_source");
+            assertThat(fields.get("socket"), is(Map.of("ip", "127.0.0.1")));
+        }
+    }
+
     @SuppressWarnings("unchecked")
     public void testLogsDefaultPipeline() throws Exception {
         RestClient client = client();