public InternalNode(Settings preparedSettings, boolean loadConfigSettings) throws ElasticsearchException {
        final Settings pSettings = settingsBuilder().put(preparedSettings)
                .put(Client.CLIENT_TYPE_SETTING, CLIENT_TYPE).build();
        Tuple<Settings, Environment> tuple = InternalSettingsPreparer.prepareSettings(pSettings, loadConfigSettings);
        tuple = new Tuple<>(TribeService.processSettings(tuple.v1()), tuple.v2());
        logger.info("initializing ...");
       //啟動插件service，加載并啟動插件
        this.pluginsService = new PluginsService(tuple.v1(), tuple.v2());
        this.settings = pluginsService.updatedSettings();
        // create the environment based on the finalized (processed) view of the settings
        this.environment = new Environment(this.settings());
        CompressorFactory.configure(settings);
       //配置node環(huán)境
        final NodeEnvironment nodeEnvironment;
        try {
            nodeEnvironment = new NodeEnvironment(this.settings, this.environment);
        } catch (IOException ex) {
            throw new ElasticsearchIllegalStateException("Failed to created node environment", ex);
        }
        boolean success = false;
        try {
       //加載各個模塊
            ModulesBuilder modules = new ModulesBuilder();
            modules.add(new Version.Module(version));
            modules.add(new CacheRecyclerModule(settings));
            modules.add(new PageCacheRecyclerModule(settings));
            modules.add(new CircuitBreakerModule(settings));
            modules.add(new BigArraysModule(settings));
            modules.add(new PluginsModule(settings, pluginsService));
            modules.add(new SettingsModule(settings));
            modules.add(new NodeModule(this));
            modules.add(new NetworkModule());
            modules.add(new ScriptModule(settings));
            modules.add(new EnvironmentModule(environment));
……
}

public Node start() {
        if (!lifecycle.moveToStarted()) {
            return this;
        }// hack around dependency injection problem (for now...)
        injector.getInstance(Discovery.class).setAllocationService(injector.getInstance(AllocationService.class));
        for (Class<? extends LifecycleComponent> plugin : pluginsService.services()) {
            injector.getInstance(plugin).start();
        }
　　　　//通過guice獲取各個模塊的service接口并啟動
        injector.getInstance(MappingUpdatedAction.class).start();
        injector.getInstance(IndicesService.class).start();
        injector.getInstance(IndexingMemoryController.class).start();
        injector.getInstance(IndicesClusterStateService.class).start();
        injector.getInstance(IndicesTTLService.class).start();
        injector.getInstance(RiversManager.class).start();
        injector.getInstance(SnapshotsService.class).start();
        injector.getInstance(TransportService.class).start();
……
}

public PluginsService(Settings settings, Environment environment) {
        super(settings);
        this.environment = environment;
        ……
        ImmutableList.Builder<Tuple<PluginInfo, Plugin>> tupleBuilder = ImmutableList.builder();
        // 加載配置插件
        String[] defaultPluginsClasses = settings.getAsArray("plugin.types");
        for (String pluginClass : defaultPluginsClasses) {
            Plugin plugin = loadPlugin(pluginClass, settings);
            PluginInfo pluginInfo = new PluginInfo(plugin.name(), plugin.description(), hasSite(plugin.name()), true, PluginInfo.VERSION_NOT_AVAILABLE);
            if (logger.isTraceEnabled()) {
                logger.trace("plugin loaded from settings [{}]", pluginInfo);
            }
            tupleBuilder.add(new Tuple<>(pluginInfo, plugin));
        }
        // 查找classpatch中的所有插件
        loadPluginsIntoClassLoader();
        if (loadClasspathPlugins) {
            tupleBuilder.addAll(loadPluginsFromClasspath(settings));
        }
        this.plugins = tupleBuilder.build();
        // We need to build a List of jvm and site plugins for checking mandatory plugins
        Map<String, Plugin> jvmPlugins = Maps.newHashMap();
        List<String> sitePlugins = Lists.newArrayList();
        for (Tuple<PluginInfo, Plugin> tuple : this.plugins) {
            jvmPlugins.put(tuple.v2().name(), tuple.v2());
            if (tuple.v1().isSite()) {
                sitePlugins.add(tuple.v1().getName());
            }
        }
        // 加載site插件
        ImmutableList<Tuple<PluginInfo, Plugin>> tuples = loadSitePlugins();
        for (Tuple<PluginInfo, Plugin> tuple : tuples) {
            sitePlugins.add(tuple.v1().getName());
        }
        // 檢驗代理插件，如果有加載不成功的插件就拋出異常，停止node啟動。
        String[] mandatoryPlugins = settings.getAsArray("plugin.mandatory", null);
        if (mandatoryPlugins != null) {
            Set<String> missingPlugins = Sets.newHashSet();
            for (String mandatoryPlugin : mandatoryPlugins) {
                if (!jvmPlugins.containsKey(mandatoryPlugin) && !sitePlugins.contains(mandatoryPlugin) && !missingPlugins.contains(mandatoryPlugin)) {
                    missingPlugins.add(mandatoryPlugin);
                }
            }
            if (!missingPlugins.isEmpty()) {
                throw new ElasticsearchException("Missing mandatory plugins [" + Strings.collectionToDelimitedString(missingPlugins, ", ") + "]");
            }
        }
……
}