Getting the Version of ElasticSearch Connected in C# & .NET

In the previous post, “Getting the Version of Redis Connected in C# & .NET”, we looked at how to get the version of Redis we are connected to without requiring a connection with admin privileges.

In this post, we will look at how to get the version of ElasticSearch we are connected to.

This is pretty straightforward to achieve.

We can make use of the fact that when we connect to the root of the ElasticSearch URL, we get the following response:

{
  "name": "67798ac2fa06",
  "cluster_name": "docker-cluster",
  "cluster_uuid": "BJW06LIiT5uZ3NGn1VFryg",
  "version": {
    "number": "9.1.2",
    "build_flavor": "default",
    "build_type": "docker",
    "build_hash": "ca1a70216fbdefbef3c65b1dff04903ea5964ef5",
    "build_date": "2025-08-11T15:04:41.449624592Z",
    "build_snapshot": false,
    "lucene_version": "10.2.2",
    "minimum_wire_compatibility_version": "8.19.0",
    "minimum_index_compatibility_version": "8.0.0"
  },
  "tagline": "You Know, for Search"
}

We can build a C# type to represent this.

First, the root type, ElasticSearchResponse

public sealed class ElasticSearchResponse
{
    [JsonPropertyName("name")] public string Name { get; set; } = string.Empty;
    [JsonPropertyName("cluster_name")] public string ClusterName { get; set; } = string.Empty;
    [JsonPropertyName("cluster_uuid")] public string ClusterUuid { get; set; } = string.Empty;
    [JsonPropertyName("version")] public VersionInfo Version { get; set; } = new();
    [JsonPropertyName("tagline")] public string Tagline { get; set; } = string.Empty;
}

We then have the inner, nested type, VersionInfo.

public sealed class VersionInfo
{
    [JsonPropertyName("number")] public string Number { get; set; } = string.Empty;
    [JsonPropertyName("build_flavor")] public string BuildFlavor { get; set; } = string.Empty;
    [JsonPropertyName("build_type")] public string BuildType { get; set; } = string.Empty;
    [JsonPropertyName("build_hash")] public string BuildHash { get; set; } = string.Empty;
    [JsonPropertyName("build_date")] public DateTime BuildDate { get; set; }
    [JsonPropertyName("build_snapshot")] public bool BuildSnapshot { get; set; }
    [JsonPropertyName("lucene_version")] public string LuceneVersion { get; set; } = string.Empty;
    [JsonPropertyName("minimum_wire_compatibility_version")] public string MinimumWireCompatibilityVersion { get; set; } = string.Empty;
    [JsonPropertyName("minimum_index_compatibility_version")] public string MinimumIndexCompatibilityVersion { get; set; } = string.Empty;
}

With these types in place, we can now make an HTTP request to ElasticSearch and serialize the response.

using System.Net.Http.Json;
using ElasticSearchVersion;

var client = new HttpClient();
const string elasticSearchRoot = "http://localhost:9200/";

var response = await client.GetFromJsonAsync<ElasticSearchResponse>(elasticSearchRoot);
Console.WriteLine(response!.Version.Number);

This will print something like this:

9.1.2

If we visualize the returned type in the debugger, we see the following:

The reason I’ve done it this way is that there is a lot of other useful information that you may want to use.

This method is a bit brittle in the sense that the ElasticSearch response can change between versions.

A more reliable, future-proof way is to make use of the ElasticSearchClient.

This has a method, InfoAsync(), that will retrieve for you the required information in a type InfoResponse.

The InfoResponse object has a property, Version, that contains the properties we are interested in.

We start by installing the package:

dotnet add package Elastic.Clients.Elasticsearch

We then update our code as follows:

var client = new ElasticsearchClient(settings);

var info = await client.InfoAsync();

Console.WriteLine($"Version: {info.Version.Number}");

If we rum this code, it will print the following:

Version: 9.1.2

If we view the InfoResponse object in the debugger, we can see that it has the same properties as those returned by the ElasticSearch response.

TLDR

We can use the ElasticSearchClient and its InfoAsyc() method to get various properties of the ElasticSearch instance we are connected to.

The code is in my GitHub.

Happy hacking!