org.apache.calcite.adapter.elasticsearch.ElasticsearchSchemaFactory Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.calcite.adapter.elasticsearch;

import org.apache.calcite.schema.Schema;
import org.apache.calcite.schema.SchemaFactory;
import org.apache.calcite.schema.SchemaPlus;

import org.apache.http.HttpHost;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Preconditions;

import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;

/**
 * Factory that creates an {@link ElasticsearchSchema}.
 *
 * Allows a custom schema to be included in a model.json file.
 */
@SuppressWarnings("UnusedDeclaration")
public class ElasticsearchSchemaFactory implements SchemaFactory {

  private static final Logger LOGGER = LoggerFactory.getLogger(ElasticsearchSchemaFactory.class);

  public ElasticsearchSchemaFactory() {
  }

  @Override public Schema create(SchemaPlus parentSchema, String name,
      Map operand) {

    final Map map = (Map) operand;

    final ObjectMapper mapper = new ObjectMapper();
    mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);

    try {

      List hosts;

      if (map.containsKey("hosts")) {
        final List configHosts = mapper.readValue((String) map.get("hosts"),
                new TypeReference>() { });

        hosts = configHosts
                .stream()
                .map(host -> HttpHost.create(host))
                .collect(Collectors.toList());
      } else if (map.containsKey("coordinates")) {
        final Map coordinates = mapper.readValue((String) map.get("coordinates"),
                new TypeReference>() { });

        hosts =  coordinates
                .entrySet()
                .stream()
                .map(entry -> new HttpHost(entry.getKey(), entry.getValue()))
                .collect(Collectors.toList());

        LOGGER.warn("Prefer using hosts, coordinates is deprecated.");
      } else {
        throw new IllegalArgumentException
        ("Both 'coordinates' and 'hosts' is missing in configuration. Provide one of them.");
      }
      final String pathPrefix = (String) map.get("pathPrefix");
      // create client
      final RestClient client = connect(hosts, pathPrefix);
      final String index = (String) map.get("index");

      return new ElasticsearchSchema(client, new ObjectMapper(), index);
    } catch (IOException e) {
      throw new RuntimeException("Cannot parse values from json", e);
    }
  }

  /**
   * Builds Elastic rest client from user configuration.
   *
   * @param hosts list of ES HTTP Hosts to connect to
   * @return newly initialized low-level rest http client for ES
   */
  private static RestClient connect(List hosts, String pathPrefix) {

    Objects.requireNonNull(hosts, "hosts or coordinates");
    Preconditions.checkArgument(!hosts.isEmpty(), "no ES hosts specified");

    RestClientBuilder builder = RestClient.builder(hosts.toArray(new HttpHost[hosts.size()]));
    if (pathPrefix != null && !pathPrefix.isEmpty()) {
      builder.setPathPrefix(pathPrefix);
    }
    return builder.build();
  }

}