问题描述：启动janusgraph连接elasticsearch报错
1360 [main] INFO org.janusgraph.diskstorage.Backend - Configuring index [search] 4351 [main] WARN org.janusgraph.diskstorage.es.rest.RestElasticSearchClient - Unable to determine Elasticsearch server version. Default to FIVE. java.net.UnknownHostException: elasticsearch at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$2.lookupAllHostAddr(Unknown Source) at java.net.InetAddress.getAddressesFromNameService(Unknown Source) at java.net.InetAddress.getAllByName0(Unknown Source) at java.net.InetAddress.getAllByName(Unknown Source) at java.net.InetAddress.getAllByName(Unknown Source) at org.apache.http.impl.conn.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:45) at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager$InternalAddressResolver.resolveRemoteAddress(PoolingNHttpClientConnectionManager.java:609) at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager$InternalAddressResolver.resolveRemoteAddress(PoolingNHttpClientConnectionManager.java:580) at org.apache.http.nio.pool.AbstractNIOConnPool.processPendingRequest(AbstractNIOConnPool.java:427) at org.apache.http.nio.pool.AbstractNIOConnPool.lease(AbstractNIOConnPool.java:276) at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.requestConnection(PoolingNHttpClientConnectionManager.java:266) at org.apache.http.impl.nio.client.AbstractClientExchangeHandler.requestConnection(AbstractClientExchangeHandler.java:363) at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.start(DefaultClientExchangeHandlerImpl.java:125) at org.apache.http.impl.nio.client.InternalHttpAsyncClient.execute(InternalHttpAsyncClient.java:141) at org.elasticsearch.client.RestClient.performRequestAsync(RestClient.java:344) at org.elasticsearch.client.RestClient.performRequestAsync(RestClient.java:326) at org.elasticsearch.client.RestClient.performRequest(RestClient.java:219) at org.elasticsearch.client.RestClient.performRequest(RestClient.java:192) at org.elasticsearch.client.RestClient.performRequest(RestClient.java:154) at org.janusgraph.diskstorage.es.rest.RestElasticSearchClient.getMajorVersion(RestElasticSearchClient.java:118) at org.janusgraph.diskstorage.es.rest.RestElasticSearchClient.<init>(RestElasticSearchClient.java:101) at org.janusgraph.diskstorage.es.rest.RestClientSetup.getElasticSearchClient(RestClientSetup.java:107) at org.janusgraph.diskstorage.es.rest.RestClientSetup.connect(RestClientSetup.java:74) at org.janusgraph.diskstorage.es.ElasticSearchSetup$1.connect(ElasticSearchSetup.java:50) at org.janusgraph.diskstorage.es.ElasticSearchIndex.interfaceConfiguration(ElasticSearchIndex.java:391) at org.janusgraph.diskstorage.es.ElasticSearchIndex.<init>(ElasticSearchIndex.java:297) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:58) at org.janusgraph.diskstorage.Backend.getImplementationClass(Backend.java:476) at org.janusgraph.diskstorage.Backend.getIndexes(Backend.java:463) at org.janusgraph.diskstorage.Backend.<init>(Backend.java:148) at org.janusgraph.graphdb.configuration.GraphDatabaseConfiguration.getBackend(GraphDatabaseConfiguration.java:1840) at org.janusgraph.graphdb.database.StandardJanusGraph.<init>(StandardJanusGraph.java:138) at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:160) at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:131) at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:111) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.tinkerpop.gremlin.structure.util.GraphFactory.open(GraphFactory.java:78) at org.apache.tinkerpop.gremlin.structure.util.GraphFactory.open(GraphFactory.java:70) at org.apache.tinkerpop.gremlin.structure.util.GraphFactory.open(GraphFactory.java:104) at org.apache.tinkerpop.gremlin.server.util.DefaultGraphManager.lambda$new$0(DefaultGraphManager.java:57) at java.util.LinkedHashMap$LinkedEntrySet.forEach(Unknown Source) at org.apache.tinkerpop.gremlin.server.util.DefaultGraphManager.<init>(DefaultGraphManager.java:55) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor.<init>(ServerGremlinExecutor.java:80) at org.apache.tinkerpop.gremlin.server.GremlinServer.<init>(GremlinServer.java:120) at org.apache.tinkerpop.gremlin.server.GremlinServer.<init>(GremlinServer.java:84) at org.apache.tinkerpop.gremlin.server.GremlinServer.main(GremlinServer.java:343) 4404 [main] WARN org.apache.tinkerpop.gremlin.server.GremlinServer - Graph [graph] configured at [conf/gremlin-server/janusgraph-berkeleyje-es-server.properties] could not be instantiated and will not be available in Gremlin Server. GraphFactory message: GraphFactory could not instantiate this Graph implementation [class org.janusgraph.core.JanusGraphFactory]解决方法：
找到启动时读取的配置文件conf/gremlin-server/janusgraph-berkeleyje-er-server.properties，修改配置文件中的index.search.hostname。 index.search.hostname=127.0.0.1
