es啟動腳本是bin目錄下的elasticsearch。其中需要加載一些環境變量，諸如ES_CLASSPATH JAVA_OPTS ?ES_JAVA_OPTS等。推薦設置ES_HEAP_SIZE的值，來這只es進程需要的內存（經驗值為系統內存的一半以上），同時設置-p參數來指定pid文件的生成位置，在es關閉的時候會用到。
腳本內容不再贅述，java主類位于org.elasticsearch.bootstrap。主要邏輯是生成了一個InternalNode節點，并且啟動了一個keepalive線程。結點的啟動代表整個es進程啟動了。
InternalNode節點是通過NodeBuilder來生成的，節點在構造函數中通過ModuleBuilder類來進行模塊的注入（是對Guice的一個封裝而已），同時生成injector實例，如下
~~~
ModulesBuilder modules = new ModulesBuilder();
modules.add(new Version.Module(version));
modules.add(new CacheRecyclerModule(settings));
modules.add(new PageCacheRecyclerModule(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));
modules.add(new NodeEnvironmentModule(nodeEnvironment));
modules.add(new ClusterNameModule(settings));
modules.add(new ThreadPoolModule(settings));
modules.add(new DiscoveryModule(settings));
modules.add(new ClusterModule(settings));
modules.add(new RestModule(settings));
modules.add(new TransportModule(settings));
if (settings.getAsBoolean("http.enabled", true)) {
modules.add(new HttpServerModule(settings));
}
modules.add(new RiversModule(settings));
modules.add(new IndicesModule(settings));
modules.add(new SearchModule());
modules.add(new ActionModule(false));
modules.add(new MonitorModule(settings));
modules.add(new GatewayModule(settings));
modules.add(new NodeClientModule());
modules.add(new BulkUdpModule());
modules.add(new ShapeModule());
modules.add(new PercolatorModule());
modules.add(new ResourceWatcherModule());
modules.add(new RepositoriesModule());
modules.add(new TribeModule());
~~~
~~~
? injector = modules.createInjector();
~~~
在InternalNode的start方法中，用injector對各個模塊完成啟動，各自負責各自的功能，如下：
~~~
injector.getInstance(Discovery.class).setAllocationService(injector.getInstance(AllocationService.class));
for (Class<? extends LifecycleComponent> plugin : pluginsService.services()) {
injector.getInstance(plugin).start();
}
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(ClusterService.class).start();
injector.getInstance(RoutingService.class).start();
injector.getInstance(SearchService.class).start();
injector.getInstance(MonitorService.class).start();
injector.getInstance(RestController.class).start();
injector.getInstance(TransportService.class).start();
DiscoveryService discoService = injector.getInstance(DiscoveryService.class).start();
discoService.waitForInitialState();
// gateway should start after disco, so it can try and recovery from gateway on "start"
injector.getInstance(GatewayService.class).start();
if (settings.getAsBoolean("http.enabled", true)) {
injector.getInstance(HttpServer.class).start();
}
injector.getInstance(BulkUdpService.class).start();
injector.getInstance(ResourceWatcherService.class).start();
injector.getInstance(TribeService.class).start();
~~~
至此，es進程啟動完畢。
guice相關介紹可以參見以下鏈接：
關鍵點在于：
@inject注釋---guice會掃描inject注釋，并對方法中出現的參數實例尋找對應注冊的實例進行初始化。
bind接口-----將接口跟具體實現類綁定
[點擊打開鏈接](http://en.wikipedia.org/wiki/Google_Guice)
[點擊打開鏈接](https://github.com/google/guice)
