Polish support for reactive Elasticsearch healthcheck

Fixes gh-21042

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/elasticsearch/ElasticsearchReactiveHealthIndicator.java

@@ -16,24 +16,31 @@
 
 package org.springframework.boot.actuate.elasticsearch;
 
-import java.util.stream.Collectors;
+import java.util.Map;
 
 import reactor.core.publisher.Mono;
 
 import org.springframework.boot.actuate.health.AbstractReactiveHealthIndicator;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.data.elasticsearch.client.reactive.ReactiveElasticsearchClient;
 
 /**
  * {@link HealthIndicator} for an Elasticsearch cluster using a
  * {@link ReactiveElasticsearchClient}.
  *
+ * @author Brian Clozel
  * @author Aleksander Lech
- * @since 2.3
+ * @since 2.3.2
  */
 public class ElasticsearchReactiveHealthIndicator extends AbstractReactiveHealthIndicator {
 
+	private static final ParameterizedTypeReference<Map<String, Object>> STRING_OBJECT_MAP = new ParameterizedTypeReference<Map<String, Object>>() {
+	};
+
+	private static final String RED_STATUS = "red";
+
 	private final ReactiveElasticsearchClient client;
 
 	public ElasticsearchReactiveHealthIndicator(ReactiveElasticsearchClient client) {
@@ -43,19 +50,28 @@ public class ElasticsearchReactiveHealthIndicator extends AbstractReactiveHealth
 
 	@Override
 	protected Mono<Health> doHealthCheck(Health.Builder builder) {
-		return this.client.status().map((status) -> {
-			if (status.isOk()) {
-				builder.up();
-			}
-			else {
-				builder.down();
-			}
-
-			builder.withDetails(status.hosts().stream().collect(Collectors
-					.toMap((host) -> host.getEndpoint().getHostString(), (host) -> host.getState().toString())));
-
-			return builder.build();
-		});
+		return this.client.execute((callback) -> callback.get().uri("/_cluster/health/").exchange())
+				.flatMap((response) -> {
+					if (response.statusCode().is2xxSuccessful()) {
+						return response.bodyToMono(STRING_OBJECT_MAP).map((body) -> {
+							String status = (String) body.get("status");
+							if (RED_STATUS.equals(status)) {
+								builder.outOfService();
+							}
+							else {
+								builder.up();
+							}
+							builder.withDetails(body);
+							return builder.build();
+						});
+					}
+					else {
+						builder.down();
+						builder.withDetail("statusCode", response.rawStatusCode());
+						builder.withDetail("reasonPhrase", response.statusCode().getReasonPhrase());
+						return response.releaseBody().thenReturn(builder.build());
+					}
+				});
 	}
 
 }