When you need an Elasticsearch index to appear the moment your application starts, the Java High Level REST Client can do the heavy lifting. Below is a concise walk-through that shows how to bootstrap an index, define its mapping, and make it searchable without ever touching Kibana.

Overview

1. Opening the connection

RestHighLevelClient es = new RestHighLevelClient(
        RestClient.builder(
            new HttpHost("127.0.0.1", 9200, "http")
        )
);

2. Describing the index

Elasticsearch accepts JSON for every thing. The snippet below creates a tiny mapping for a "product" index with two fields.

String mapping = """
{
  "mappings": {
    "properties": {
      "sku":   { "type": "keyword" },
      "price": { "type": "double"  }
    }
  }
}
""";

3. Sending the definition

CreateIndexRequest request = new CreateIndexRequest("product")
        .source(mapping, XContentType.JSON);

CreateIndexResponse resp = es.indices().create(request, RequestOptions.DEFAULT);
if (resp.isAcknowledged()) {
    System.out.println("Index created");
}

4. Verifying readiness

boolean ready = es.indices()
                   .exists(new GetIndexRequest("product"), RequestOptions.DEFAULT);
System.out.println("Index exists? " + ready);

Comlpete runnable snippet

import org.apache.http.HttpHost;
import org.elasticsearch.client.*;
import org.elasticsearch.client.indices.*;

public class AutoIndexCreator {
    public static void main(String[] args) throws Exception {
        try (RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")))) {

            String mapping = """
            {
              "mappings": {
                "properties": {
                  "sku":   { "type": "keyword" },
                  "price": { "type": "double"  }
                }
              }
            }
            """;

            CreateIndexRequest req = new CreateIndexRequest("product")
                    .source(mapping, XContentType.JSON);

            CreateIndexResponse resp = client.indices().create(req, RequestOptions.DEFAULT);
            System.out.println("Acknowledged = " + resp.isAcknowledged());
        }
    }
}