Basic authentication

Configuring basic authentication can be done by providing an HttpClientConfigCallback while building the RestClient through its builder. The interface has one method that receives an instance of org.apache.http.impl.nio.client.HttpAsyncClientBuilder as an argument and has the same return type. The http client builder can be modified and then returned. In the following example we set a default credentials provider that requires basic authentication.

final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
credentialsProvider.setCredentials(AuthScope.ANY,
        new UsernamePasswordCredentials("user", "password"));

RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200))
        .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
        })
        .build();

You can disable Preemptive Authentication, which means that every request will be sent without authorization headers to see if it is accepted and, upon receiving a HTTP 401 response, it will resend the exact same request with the basic authentication header. If you wish to do this, then you can do so by disabling it via the HttpAsyncClientBuilder:

final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
credentialsProvider.setCredentials(AuthScope.ANY,
        new UsernamePasswordCredentials("user", "password"));

RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200))
        .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                // disable preemptive authentication
                httpClientBuilder.disableAuthCaching();
                return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
        })
        .build();