How to Properly Close Raw RestClient When Using Elastic Search 5.5.0 for Optimal Performance?

Question

Am using a Spring Boot 1.5.4.RELEASE Microservice to connect to an ElasticSearch 5.5.0 instance using the low level Rest Client that ElasticSearch provides.

pom.xml<

Answer 1

It's is not a good practice to create a RestClient on every single request. You should create a single instance via a configuration bean like the one below:

@Configuration
public class ElasticsearchConfig {

    @Value("${elasticsearch.host}")
    private String host;

    @Value("${elasticsearch.port}")
    private int port;

    @Bean
    public RestClient restClient() {
        return RestClient.builder(new HttpHost(host, port))
        .setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
            @Override
            public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder requestConfigBuilder) {
                return requestConfigBuilder.setConnectTimeout(5000).setSocketTimeout(60000);
            }
        }).setMaxRetryTimeoutMillis(60000).build();
    }
}

And then in your SearchController class you can inject it like this (and also add a cleanup method to close the restClient instance when your container goes down):

@RestController
@RequestMapping("/api/v1")
public class SearchController {

    @Autowired
    private RestClient restClient;

    @RequestMapping(value = "/search", method = RequestMethod.GET, produces="application/json" )
    public ResponseEntity<Object> getSearchQueryResults(@RequestParam(value = "criteria") String criteria) throws IOException {

        // Setup HTTP Headers
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "application/json");

        // Setup query and send and return ResponseEntity...

        Response response = this.restClient.performRequest(...);

    }

    @PreDestroy
    public void cleanup() {
        try {
            logger.info("Closing the ES REST client");
            this.restClient.close();
        } catch (IOException ioe) {
            logger.error("Problem occurred when closing the ES REST client", ioe);
        }
    }

}