c# - 避免出现ElasticSearch错误503服务器不可用:使用WaitForStatus

Question

当我启动程序时，我运行ElasticSearch Service并检查索引是否存在以及是否有任何文档，假设我只是运行ES服务，并且我具有以下两个功能:

public ElasticClient getElasticSearchClient()
{
    ConnectionSettings connectionSettings = new Nest.ConnectionSettings(new Uri("http://localhost:9200"))
                                                    .DefaultIndex("myindex")
                                                    .DisableDirectStreaming();
    ElasticClient client = new ElasticClient(connectionSettings);
    //var health = client.Cluster.Health("myindex", a => (a.WaitForStatus(WaitForStatus.Yellow)).Timeout(50));
    return client;
}

public void checkElasticsearchIndex()
{
    var client = getElasticSearchClient();

    var health = this.client.Cluster.Health("myindex", a => (a.WaitForStatus(WaitForStatus.Yellow)));

    CountResponse count = client.Count<myobject>();

    if (!client.Indices.Exists("myindex").IsValid || count.Count == 0)
    {
        BulkWriteAllToIndexES(client);
    }
}

在checkElasticsearchIndex函数中，

计数操作失败，并显示以下错误消息:

OriginalException:Elasticsearch.Net.ElasticsearchClientException:远程服务器返回错误:(503)服务器不可用。调用:状态代码503来自:GET / myindex / _count。 ServerError:类型:search_phase_execution_exception原因:“所有分片均失败” ---> System.Net.WebException:远程服务器返回错误:(503)服务器不可用。

运行状况也会失败:

OriginalException:Elasticsearch.Net.ElasticsearchClientException:无法连接到远程服务器。 call :状态代码未知:GET / _cluster / health / myindex？wait_for_status =黄色---> System.Net.WebException:无法连接到远程服务器---> System.Net.Sockets.SocketException:无法建立连接因为目标计算机主动拒绝它而被执行127.0.0.1:9200

如您所见，我已经尝试了Cluster WaitForStatus，但是没有用。

我的问题:有什么方法可以等待客户端/集群/节点准备好并且没有任何异常？

Answer 1

听起来您在启动程序的同时正在启动Elasticsearch进程，但是Elasticsearch花费比准备程序所需的时间更长的时间。

如果是这样，您可能会对使用.NET客户端用于针对Elasticsearch的集成测试的the same abstractions感兴趣。抽象从Elasticsearch进程中读取输出，以知道何时准备就绪，并阻塞直到发生这种情况。它们是available on an AppVeyor CI package feed(计划将来将它们发布给Nuget)。

有some examples of how to spin up a cluster with the abstractions。对于单节点，它将类似于

using System;
using Elastic.Managed.Configuration;
using Elastic.Managed.ConsoleWriters;
using Elastic.Managed.FileSystem;

namespace Elastic.Managed.Example
{
    class Program
    {
        static void Main(string[] args)
        {
            var version = "7.5.1";
            var esHome = Environment.ExpandEnvironmentVariables($@"%LOCALAPPDATA%\ElasticManaged\{version}\elasticsearch-{version}");

            using (var node = new ElasticsearchNode(version, esHome))
            {
                node.SubscribeLines(new LineHighlightWriter());
                if (!node.WaitForStarted(TimeSpan.FromMinutes(2))) throw new Exception();

                // do your work here
            }
        }
    }
}

假设已经下载了Elasticsearch 7.5.1 zip，并且存在于%LOCALAPPDATA%\ElasticManaged\7.5.1\elasticsearch-7.5.1。还有更复杂的examples of how to integrate this into tests with xUnit.

您可以use the EphemeralCluster components下载，配置和运行Elasticsearch

var plugins = new ElasticsearchPlugins(ElasticsearchPlugin.RepositoryAzure, ElasticsearchPlugin.IngestAttachment);
var config = new EphemeralClusterConfiguration("7.5.1", ClusterFeatures.XPack, plugins, numberOfNodes: 1);
using (var cluster = new EphemeralCluster(config))
{
    cluster.Start();

    var nodes = cluster.NodesUris();
    var connectionPool = new StaticConnectionPool(nodes);
    var settings = new ConnectionSettings(connectionPool).EnableDebugMode();
    var client = new ElasticClient(settings);

    Console.Write(client.CatPlugins().DebugInformation);
}