Connecting to elasticsearch cluster in NEST - elasticsearch

Question

Let's assume I have several elasticsearch machines in a cluster: 192.168.1.1, 192.168.1.2 and 192.168.1.3
Any of the machines can go down. It doesn't look like NEST supports providing a range of IPs to try to connect.
So how do I make sure I connect to any of the available machines from Nest? Just try to open connection to one, if TryConnect didn't work, try another?

Answer 1

You can run a local ES instance at your application server (eg your web server) and config it to work as a load balancer:
Set node.client: true (or node.master: false and node.data: false) for this local ES config to make it a load balancer. This mean ES will not become master nor contains data
Config it to join the cluster (your 3 nodes don't need to know this ES)
Config NEST to use local ES as your search server
Then this ES become a part of your cluster, and will distribute your requests to suitable nodes
If you don't want "load balancer", then you have to manually checking on client side to determine which node is alive.

Answer 2

Since you have a small set of nodes, you can use a StaticConnectionPool:
var uri1 = new Uri("192.168.1.1");
var uri2 = new Uri("192.168.1.2");
var uri3 = new Uri("192.168.1.3");
var uris = new List<Uri> { uri1, uri2, uri3 };
var connectionPool = new StaticConnectionPool(uris);
var connectionSettings = new ConnectionSettings(connectionPool); // <-- need to be reused
var client = new ElasticClient(connectionSettings);
An important point to keep in mind is to reuse the same ConnectionSetting when creating a new elastic client, since elasticsearch cache is per ConnectionSetting. See this GitHub post:
...In any case its important to share the same ConnectionSettings
instance across any elastic client you instantiate. ElasticClient can
be a singleton or not as long as each instance shares the same
ConnectionSettings instance.
All of our caches are per ConnectionSettings, this includes
serialization caches.
Also a single ConnectionSettings holds a single IConnectionPool and
IConnection something you definitely want to reuse across requests.

Answer 3

I would set up one of the nodes as a load balancer. Meaning that the URL your are calling should allways be up.
Though if you increase the number of replicas you can call any of the nodes by URL and still access the same data. ElasticSearch does not care which one you access while in a cluster. So you could build your own range of ips in your application.