Encrypted communication

Encrypted communication can also be configured through the HttpClientConfigCallback. The org.apache.http.impl.nio.client.HttpAsyncClientBuilder received as an argument exposes multiple methods to configure encrypted communication: setSSLContext, setSSLSessionStrategy and setConnectionManager, in order of precedence from the least important. The following is an example:

KeyStore truststore = KeyStore.getInstance("jks");
try (InputStream is = Files.newInputStream(keyStorePath)) {
    truststore.load(is, keyStorePass.toCharArray());
}
SSLContextBuilder sslBuilder = SSLContexts.custom().loadTrustMaterial(truststore, null);
final SSLContext sslContext = sslBuilder.build();
RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "https"))
        .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                return httpClientBuilder.setSSLContext(sslContext);
            }
        });

If no explicit configuration is provided, the system default configuration will be used.