CODEWITHSUNDEEP
elasticsearchnest
Renjith Thomas
Renjith Thomas

Reputation: 55

how cluster failover works in ElasticSearch using NEST

I am new in Elastic search. I want to know how the cluster failover works in ES using NEST. I went through available links http://nest.azurewebsites.net/elasticsearch-net/cluster-failover.html and http://nest.azurewebsites.net/elasticsearch-net/connecting.html. But it is not much clear for me.

Suppose i have two nodes. Node1(10.20.2.1:9203) and node2(10.20.2.2:9204). Both nodes are connected to single cluster 'TestCluster'. My requirement is that, if any of the node is down, i want to get the data from live node.

My config file for Node1(10.20.2.1:9203) is as follows

cluster.name: TestCluster
node.name: "Node1"
node.master: true
node.data: true
network.host: 10.20.2.1
http.port: 9203

My config file for Node2(10.20.2.2:9204) is as follows

cluster.name: TestCluster
node.name: "Node2"
node.master: false
node.data: true
network.host: 10.20.2.2
http.port: 9204

I am accessing the ES client as follows

private static ElasticClient ElasticClientNew
        {
            get
            {
                var node = new Uri("http://10.20.2.1:9203");
                var node1 = new Uri("http://10.20.2.2:9204");
                var connectionPool = new SniffingConnectionPool(new[] { node, node1 });
                var setting = new ConnectionSettings(connectionPool)
                                    .SniffOnConnectionFault(false)
                                    .SniffOnStartup(false)
                                    .SniffLifeSpan(TimeSpan.FromMinutes(1));
                return new ElasticClient(setting);
            }
        }

I am using this ES client for searching as follows

var result = ElasticClientNew.Search<Attendance>(s => s
                            .From(0)
                            .Size(5000)
                            .Index("attendance").Type("Worker"));

I am running the MVS application from node1, and elasticsearch service is stopped in this machine. But the ES service is running in node2. When i try to search, am getting error as follows

Failed after retrying 1 times: 'POST attendance/Worker/_search'. 
InnerException: PingException, InnerMessage: Pinging http://10.20.2.1:9203 caused an exception, InnerStackTrace:    at Elasticsearch.Net.Connection.Transport.Ping(ITransportRequestState requestState) in c:\Users\gmarz\code\elasticsearch-net\src\Elasticsearch.Net\Connection\Transport.cs:line 96
   at Elasticsearch.Net.Connection.Transport.DoRequest[T](TransportRequestState`1 requestState) in c:\Users\gmarz\code\elasticsearch-net\src\Elasticsearch.Net\Connection\Transport.cs:line 334

Please suggest how the cluster failover can be achieved in my application.

Upvotes: 2

Views: 2425

Answers (2)

Srini2014
Srini2014

Reputation: 1

I have similar issue:

When I tried connecting using StaticConnection pool, I am getting following error:

An unhandled exception of type 'Elasticsearch.Net.Exceptions.MaxRetryException' occurred in Elasticsearch.Net.dll

Additional information: Failed after retrying 0 times: 'POST els_logentries/logentries/_search'.

AS I Run again, It works fine.

        var node1 = new Uri("http://192.168.115.102:9200");
        var node2 = new Uri("http://192.168.115.102:9200");

        var connectionPool = new StaticConnectionPool(new List<Uri>() { node1,node2});
        var settings = new ConnectionSettings(connectionPool, defaultIndex: "els_logentries");

        ElasticClient client = new ElasticClient(settings);

        var results = client.Search<Logentries>(s => s
            .Type("logentries")
             .Query(q=>q
            .Bool(bq=>bq
            .Must(
            mq=>mq.MatchAll()
                )    )));

Upvotes: 0

Martijn Laarman
Martijn Laarman

Reputation: 13536

The problem is that only one of the nodes has 

node.master: true

set so when that node goes down the other node is masterless and turns off as well.

Upvotes: 1

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