org.elasticsearch.discovery.DiscoveryModule Maven / Gradle / Ivy

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/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.discovery;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.coordination.Coordinator;
import org.elasticsearch.cluster.coordination.ElectionStrategy;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.RerouteService;
import org.elasticsearch.cluster.routing.allocation.AllocationService;
import org.elasticsearch.cluster.service.ClusterApplier;
import org.elasticsearch.cluster.service.MasterService;
import org.elasticsearch.common.Randomness;
import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
import org.elasticsearch.common.network.NetworkService;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.TransportAddress;
import org.elasticsearch.gateway.GatewayMetaState;
import org.elasticsearch.monitor.NodeHealthService;
import org.elasticsearch.plugins.DiscoveryPlugin;
import org.elasticsearch.transport.TransportService;

import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;

import static org.elasticsearch.node.Node.NODE_NAME_SETTING;

/**
 * A module for loading classes for node discovery.
 */
public class DiscoveryModule {
    private static final Logger logger = LogManager.getLogger(DiscoveryModule.class);

    public static final String ZEN2_DISCOVERY_TYPE = "zen";

    public static final String SINGLE_NODE_DISCOVERY_TYPE = "single-node";

    public static final Setting DISCOVERY_TYPE_SETTING =
        new Setting<>("discovery.type", ZEN2_DISCOVERY_TYPE, Function.identity(), Property.NodeScope);
    public static final Setting> DISCOVERY_SEED_PROVIDERS_SETTING =
        Setting.listSetting("discovery.seed_providers", Collections.emptyList(), Function.identity(),
            Property.NodeScope);

    public static final String DEFAULT_ELECTION_STRATEGY = "default";

    public static final Setting ELECTION_STRATEGY_SETTING =
        new Setting<>("cluster.election.strategy", DEFAULT_ELECTION_STRATEGY, Function.identity(), Property.NodeScope);

    private final Discovery discovery;

    public DiscoveryModule(Settings settings, TransportService transportService,
                           NamedWriteableRegistry namedWriteableRegistry, NetworkService networkService, MasterService masterService,
                           ClusterApplier clusterApplier, ClusterSettings clusterSettings, List plugins,
                           AllocationService allocationService, Path configFile, GatewayMetaState gatewayMetaState,
                           RerouteService rerouteService, NodeHealthService nodeHealthService) {
        final Collection> joinValidators = new ArrayList<>();
        final Map> hostProviders = new HashMap<>();
        hostProviders.put("settings", () -> new SettingsBasedSeedHostsProvider(settings, transportService));
        hostProviders.put("file", () -> new FileBasedSeedHostsProvider(configFile));
        final Map electionStrategies = new HashMap<>();
        electionStrategies.put(DEFAULT_ELECTION_STRATEGY, ElectionStrategy.DEFAULT_INSTANCE);
        for (DiscoveryPlugin plugin : plugins) {
            plugin.getSeedHostProviders(transportService, networkService).forEach((key, value) -> {
                if (hostProviders.put(key, value) != null) {
                    throw new IllegalArgumentException("Cannot register seed provider [" + key + "] twice");
                }
            });
            BiConsumer joinValidator = plugin.getJoinValidator();
            if (joinValidator != null) {
                joinValidators.add(joinValidator);
            }
            plugin.getElectionStrategies().forEach((key, value) -> {
                if (electionStrategies.put(key, value) != null) {
                    throw new IllegalArgumentException("Cannot register election strategy [" + key + "] twice");
                }
            });
        }

        List seedProviderNames = DISCOVERY_SEED_PROVIDERS_SETTING.get(settings);
        // for bwc purposes, add settings provider even if not explicitly specified
        if (seedProviderNames.contains("settings") == false) {
            List extendedSeedProviderNames = new ArrayList<>();
            extendedSeedProviderNames.add("settings");
            extendedSeedProviderNames.addAll(seedProviderNames);
            seedProviderNames = extendedSeedProviderNames;
        }

        final Set missingProviderNames = new HashSet<>(seedProviderNames);
        missingProviderNames.removeAll(hostProviders.keySet());
        if (missingProviderNames.isEmpty() == false) {
            throw new IllegalArgumentException("Unknown seed providers " + missingProviderNames);
        }

        List filteredSeedProviders = seedProviderNames.stream()
            .map(hostProviders::get).map(Supplier::get).collect(Collectors.toList());

        String discoveryType = DISCOVERY_TYPE_SETTING.get(settings);

        final SeedHostsProvider seedHostsProvider = hostsResolver -> {
            final List addresses = new ArrayList<>();
            for (SeedHostsProvider provider : filteredSeedProviders) {
                addresses.addAll(provider.getSeedAddresses(hostsResolver));
            }
            return Collections.unmodifiableList(addresses);
        };

        final ElectionStrategy electionStrategy = electionStrategies.get(ELECTION_STRATEGY_SETTING.get(settings));
        if (electionStrategy == null) {
            throw new IllegalArgumentException("Unknown election strategy " + ELECTION_STRATEGY_SETTING.get(settings));
        }

        if (ZEN2_DISCOVERY_TYPE.equals(discoveryType) || SINGLE_NODE_DISCOVERY_TYPE.equals(discoveryType)) {
            discovery = new Coordinator(NODE_NAME_SETTING.get(settings),
                settings, clusterSettings,
                transportService, namedWriteableRegistry, allocationService, masterService, gatewayMetaState::getPersistedState,
                seedHostsProvider, clusterApplier, joinValidators, new Random(Randomness.get().nextLong()), rerouteService,
                electionStrategy, nodeHealthService);
        } else {
            throw new IllegalArgumentException("Unknown discovery type [" + discoveryType + "]");
        }

        logger.info("using discovery type [{}] and seed hosts providers {}", discoveryType, seedProviderNames);
    }

    public static boolean isSingleNodeDiscovery(Settings settings) {
        return SINGLE_NODE_DISCOVERY_TYPE.equals(DISCOVERY_TYPE_SETTING.get(settings));
    }

    public Discovery getDiscovery() {
        return discovery;
    }
}