使用Spring Data Elasticsearch连接elasticsearch时，正常情况下只需要在application.properites文件中添加如下配置即可连接：
spring.data.elasticsearch.repositories.enabled = true
spring.data.elasticsearch.cluster-name = es-cluster
spring.data.elasticsearch.cluster-nodes = 127.0.0.1:9300
以看到Spring Data Elasticsearch连接elasticsearch很简单。
上面说的是正常情况，但是有些情况下连接需要验证。比如安装x-pack（旧版本的Shield、Marvel等）之后，访问elasticsearch就需要验证（未开启匿名访问），默认用户名/密码是：elastic/changeme，参考官方文档了解更多细节。
如果不做相应的修改就会报错
org.elasticsearch.transport.RemoteTransportException: [i9Vl_pG][10.111.27.202:9300][cluster:monitor/nodes/liveness]
Caused by: org.elasticsearch.ElasticsearchSecurityException: missing authentication token for action [cluster:monitor/nodes/liveness]
at org.elasticsearch.xpack.security.support.Exceptions.authenticationError(Exceptions.java:36) ~[na:na]
at org.elasticsearch.xpack.security.authc.DefaultAuthenticationFailureHandler.missingToken(DefaultAuthenticationFailureHandler.java:74) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$AuditableTransportRequest.anonymousAccessDenied(AuthenticationService.java:541) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.lambda$handleNullToken$17(AuthenticationService.java:357) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.handleNullToken(AuthenticationService.java:362) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.consumeToken(AuthenticationService.java:277) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.lambda$extractToken$7(AuthenticationService.java:249) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.extractToken(AuthenticationService.java:266) ~[na:na]
at org.elasticsearch.xpack.security.authc.AuthenticationService$Authenticator.lambda$null$0(AuthenticationService.java:201) ~[na:na]
at org.elasticsearch.action.ActionListener$1.onResponse(ActionListener.java:60) ~[elasticsearch-5.6.8.jar:5.6.8]
at org.elasticsearch.xpack.security.authc.TokenService.getAndValidateToken(TokenService.java:239) ~[na:na]
在这样的情况下，Spring Data Elasticsearch 该如何设置才能连接到 elasticsearch？目前最新版的 Spring Data Elasticsearch 2.1.6.Release 还不能通过配置的形式来完成。那要如何做，更换TransportClient即可！
修改依赖
<repository>
<id>elasticsearch-releases</id>
<url>https://artifacts.elastic.co/maven</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
...
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-elasticsearch</artifactId>
<exclusions>
<exclusion>
<groupId>org.elasticsearch.client</groupId>
<artifactId>transport</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>x-pack-transport</artifactId>
<version>5.5.0</version>
</dependency>
x-pack-transport 的版本号保持与elasticsearch一致。
重新实例化 TransportClient
@Bean
public TransportClient transportClient() throws UnknownHostException {
TransportClient client = new PreBuiltXPackTransportClient(Settings.builder()
.put("cluster.name", "es-cluster")
.put("xpack.security.user", "elastic:changeme")
.build())
.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), 9300));
return client;
}
就这么多，之前属性文件中的配置可以删除了，这样就能保证连接验证通过。