Java tutorial
/* * Licensed to Elasticsearch under one or more contributor * license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright * ownership. Elasticsearch licenses this file to you under * the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.elasticsearch.client.sniff; import com.fasterxml.jackson.core.JsonFactory; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonToken; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.HttpEntity; import org.apache.http.HttpHost; import org.elasticsearch.client.Response; import org.elasticsearch.client.RestClient; import java.io.IOException; import java.io.InputStream; import java.net.URI; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.Objects; import java.util.concurrent.TimeUnit; /** * Class responsible for sniffing the http hosts from elasticsearch through the nodes info api and returning them back. * Compatible with elasticsearch 5.x and 2.x. */ public final class ElasticsearchHostsSniffer implements HostsSniffer { private static final Log logger = LogFactory.getLog(ElasticsearchHostsSniffer.class); public static final long DEFAULT_SNIFF_REQUEST_TIMEOUT = TimeUnit.SECONDS.toMillis(1); private final RestClient restClient; private final Map<String, String> sniffRequestParams; private final Scheme scheme; private final JsonFactory jsonFactory = new JsonFactory(); /** * Creates a new instance of the Elasticsearch sniffer. It will use the provided {@link RestClient} to fetch the hosts, * through the nodes info api, the default sniff request timeout value {@link #DEFAULT_SNIFF_REQUEST_TIMEOUT} and http * as the scheme for all the hosts. * @param restClient client used to fetch the hosts from elasticsearch through nodes info api. Usually the same instance * that is also provided to {@link Sniffer#builder(RestClient)}, so that the hosts are set to the same * client that was used to fetch them. */ public ElasticsearchHostsSniffer(RestClient restClient) { this(restClient, DEFAULT_SNIFF_REQUEST_TIMEOUT, ElasticsearchHostsSniffer.Scheme.HTTP); } /** * Creates a new instance of the Elasticsearch sniffer. It will use the provided {@link RestClient} to fetch the hosts * through the nodes info api, the provided sniff request timeout value and scheme. * @param restClient client used to fetch the hosts from elasticsearch through nodes info api. Usually the same instance * that is also provided to {@link Sniffer#builder(RestClient)}, so that the hosts are set to the same * client that was used to sniff them. * @param sniffRequestTimeoutMillis the sniff request timeout (in milliseconds) to be passed in as a query string parameter * to elasticsearch. Allows to halt the request without any failure, as only the nodes * that have responded within this timeout will be returned. * @param scheme the scheme to associate sniffed nodes with (as it is not returned by elasticsearch) */ public ElasticsearchHostsSniffer(RestClient restClient, long sniffRequestTimeoutMillis, Scheme scheme) { this.restClient = Objects.requireNonNull(restClient, "restClient cannot be null"); if (sniffRequestTimeoutMillis < 0) { throw new IllegalArgumentException("sniffRequestTimeoutMillis must be greater than 0"); } this.sniffRequestParams = Collections.<String, String>singletonMap("timeout", sniffRequestTimeoutMillis + "ms"); this.scheme = Objects.requireNonNull(scheme, "scheme cannot be null"); } /** * Calls the elasticsearch nodes info api, parses the response and returns all the found http hosts */ public List<HttpHost> sniffHosts() throws IOException { Response response = restClient.performRequest("get", "/_nodes/http", sniffRequestParams); return readHosts(response.getEntity()); } private List<HttpHost> readHosts(HttpEntity entity) throws IOException { try (InputStream inputStream = entity.getContent()) { JsonParser parser = jsonFactory.createParser(inputStream); if (parser.nextToken() != JsonToken.START_OBJECT) { throw new IOException("expected data to start with an object"); } List<HttpHost> hosts = new ArrayList<>(); while (parser.nextToken() != JsonToken.END_OBJECT) { if (parser.getCurrentToken() == JsonToken.START_OBJECT) { if ("nodes".equals(parser.getCurrentName())) { while (parser.nextToken() != JsonToken.END_OBJECT) { JsonToken token = parser.nextToken(); assert token == JsonToken.START_OBJECT; String nodeId = parser.getCurrentName(); HttpHost sniffedHost = readHost(nodeId, parser, this.scheme); if (sniffedHost != null) { logger.trace("adding node [" + nodeId + "]"); hosts.add(sniffedHost); } } } else { parser.skipChildren(); } } } return hosts; } } private static HttpHost readHost(String nodeId, JsonParser parser, Scheme scheme) throws IOException { HttpHost httpHost = null; String fieldName = null; while (parser.nextToken() != JsonToken.END_OBJECT) { if (parser.getCurrentToken() == JsonToken.FIELD_NAME) { fieldName = parser.getCurrentName(); } else if (parser.getCurrentToken() == JsonToken.START_OBJECT) { if ("http".equals(fieldName)) { while (parser.nextToken() != JsonToken.END_OBJECT) { if (parser.getCurrentToken() == JsonToken.VALUE_STRING && "publish_address".equals(parser.getCurrentName())) { URI boundAddressAsURI = URI.create(scheme + "://" + parser.getValueAsString()); httpHost = new HttpHost(boundAddressAsURI.getHost(), boundAddressAsURI.getPort(), boundAddressAsURI.getScheme()); } else if (parser.getCurrentToken() == JsonToken.START_OBJECT) { parser.skipChildren(); } } } else { parser.skipChildren(); } } } //http section is not present if http is not enabled on the node, ignore such nodes if (httpHost == null) { logger.debug("skipping node [" + nodeId + "] with http disabled"); return null; } return httpHost; } public enum Scheme { HTTP("http"), HTTPS("https"); private final String name; Scheme(String name) { this.name = name; } @Override public String toString() { return name; } } }