How do i stop hibernate search from sniffing the nodes of a non-existent local elastic search server? - elasticsearch

Question

I've created a open search service domain on AWS and i've set the property hibernate.search.backend.uris to the address of that domain. Everything works fine, i'm able to index my entity tables and can run search queries against the open search service domain.
Yet for some reason hibernate search still routinely tries to connect to localhost:9200 in order to perform a node sniffing routine. This obviously doesn't work and the exception [es_rest_client_sniffer[T#1]] Sniffer - error while sniffing nodes java.net.ConnectException: Connection refused: no further information is thown.
How do i stop hibernate search from performing this futile action? It keeps trying to sniff the nodes every few minutes or so. I've tried setting the fields hibernate.search.backend.hosts and hibernate.search.backend.protocol instead of .uris. But even when i set those properties instead hibernate search still tries to interact with a non-existent elastic search service on localhost. I am running hibernate search 6.1.5.Final. The elastic search version is set to 7.16.3. Here are all the relevant properties that i set programmatically.
jpaProperties.put("hibernate.search.backend.aws.credentials.type", "static");
jpaProperties.put("hibernate.search.backend.aws.credentials.access_key_id", awsId);
jpaProperties.put("hibernate.search.backend.aws.credentials.secret_access_key", awsKey);
jpaProperties.put("hibernate.search.backend.aws.region", openSearchAwsInstanceRegion);
jpaProperties.put("hibernate.search.backend.aws.signing.enabled", true);
//--------------------------------------------------------------------------------------------
jpaProperties.put("hibernate.search.automatic_indexing.synchronization.strategy", indexSynchronizationStrategy);
jpaProperties.put("hibernate.search.backend.request_timeout", requestTimeout);
jpaProperties.put("hibernate.search.backend.connection_timeout", elasticSearchConnectionTimeout);
jpaProperties.put("hibernate.search.backend.read_timeout", readTimeout);
jpaProperties.put("hibernate.search.backend.max_connections", maximumElasticSearchConnections);
jpaProperties.put("hibernate.search.backend.max_connections_per_route", maximumElasticSearchConnectionsPerRout);
jpaProperties.put("hibernate.search.schema_management.strategy", schemaManagementStrategy);
jpaProperties.put("hibernate.search.backend.analysis.configurer", "class:config.EnhancedLuceneAnalysisConfig");
jpaProperties.put("hibernate.search.backend.uris", elasticSearchHostAddress);
jpaProperties.put("hibernate.search.backend.directory.type", "local-filesystem");
jpaProperties.put("hibernate.search.backend.type", "elasticsearch");
jpaProperties.put("hibernate.search.backend.directory.root", luceneAbsoluteFilePath);
jpaProperties.put("hibernate.search.backend.lucene_version", "LUCENE_CURRENT");
jpaProperties.put("hibernate.search.backend.io.writer.infostream", true);
EDIT:
These are all the elastic search related dependencies that my application uses.
<dependency>
<groupId>org.hibernate.search</groupId>
<artifactId>hibernate-search-mapper-orm</artifactId>
<version>6.1.5.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.search</groupId>
<artifactId>hibernate-search-backend-elasticsearch-aws</artifactId>
<version>6.1.5.Final</version>
</dependency>
Heres the stacktrace,
[ERROR] 2022-07-21 14:33:58.402 [es_rest_client_sniffer[T#1]] Sniffer - error while sniffing nodes
java.net.ConnectException: Connection refused: no further information
at org.elasticsearch.client.RestClient.extractAndWrapCause(RestClient.java:918) ~[elasticsearch-rest-client-7.17.3.jar:7.17.3]
at org.elasticsearch.client.RestClient.performRequest(RestClient.java:299) ~[elasticsearch-rest-client-7.17.3.jar:7.17.3]
at org.elasticsearch.client.RestClient.performRequest(RestClient.java:287) ~[elasticsearch-rest-client-7.17.3.jar:7.17.3]
at org.elasticsearch.client.sniff.ElasticsearchNodesSniffer.sniff(ElasticsearchNodesSniffer.java:106) ~[elasticsearch-rest-client-sniffer-7.17.3.jar:7.17.3]
at org.elasticsearch.client.sniff.Sniffer.sniff(Sniffer.java:209) ~[elasticsearch-rest-client-sniffer-7.17.3.jar:7.17.3]
at org.elasticsearch.client.sniff.Sniffer$Task.run(Sniffer.java:140) ~[elasticsearch-rest-client-sniffer-7.17.3.jar:7.17.3]
at org.elasticsearch.client.sniff.Sniffer$1.run(Sniffer.java:81) ~[elasticsearch-rest-client-sniffer-7.17.3.jar:7.17.3]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539) ~[?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[?:?]
at java.lang.Thread.run(Thread.java:833) ~[?:?]
Caused by: java.net.ConnectException: Connection refused: no further information
at sun.nio.ch.Net.pollConnect(Native Method) ~[?:?]
at sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[?:?]
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:946) ~[?:?]
at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvent(DefaultConnectingIOReactor.java:174) ~[httpcore-nio-4.4.15.jar:4.4.15]
at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvents(DefaultConnectingIOReactor.java:148) ~[httpcore-nio-4.4.15.jar:4.4.15]
at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:351) ~[httpcore-nio-4.4.15.jar:4.4.15]
at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.execute(PoolingNHttpClientConnectionManager.java:221) ~[httpasyncclient-4.1.5.jar:4.1.5]
at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClientBase.java:64) ~[httpasyncclient-4.1.5.jar:4.1.5]
... 1 more
This stacktrace was copied after i had removed <elasticsearch.version>7.16.3</elasticsearch.version> so see whether that would solve the problem. If the version is missing hibernate search seems to default to version 7.17.3

Answer 1

It took a while but i finally found the source of the problem.
Apparently spring boot has a built-in autoconfiguration class for Elastic search called ElasticsearchRestClientAutoConfiguration. The code in this class is run by default and it initializes a org.elasticsearch.client.RestClient that that has a node sniffer enabled by default. If no elastic search server is running on localhost this RestClient will keep throwing exceptions because there is nothing to connect to.
Because this class is not part of the hibernate search java library settings such as hibernate.search.backend.discovery.enabled = false do not influence this RestClient or its Sniffer.
You can prevent Spring from creating this RestClient by telling Spring not to run ElasticsearchRestClientAutoConfiguration. This can be done in two ways.
Firstly you can add the following property to your application.properties:
spring.autoconfigure.exclude = org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration
Second, you can also exclude this autoconfiguration class by adding it as a value to the exclude argument of the #SpringBootApplication annotation. For instance:
#SpringBootApplication(exclude ={ElasticsearchRestClientAutoConfiguration.class})
public class MyConfiguration {

Answer 2

Hibernate Search will only enable node discovery (create a sniffer) if the configuration property hibernate.search.backend.discovery.enabled is set to true, and by default it's false.
If the properties you listed are the only ones you set, then I don't think Hibernate Search is creating this sniffer. The sniffer also doesn't use the URIs you passed to Hibernate Search, so that as well tends to prove the sniffer is not created by Hibernate Search.
If you don't believe me, see by yourself by starting your app in debug mode and putting a breakpoint in org.hibernate.search.backend.elasticsearch.client.impl.ElasticsearchClientFactoryImpl#createSniffer.
I think you probably have something else in your application creating an Elasticsearch client and a sniffer, and that something else is not completely configured. Try launching your application in debug mode and putting breakpoints in the constructors of org.elasticsearch.client.sniff.Sniffer?