♻️ Updated discovery resolver

DysonNetwork.Shared/Registry/RegistrarServiceEndpointProvider.cs

@@ -0,0 +1,41 @@
+using System.Net;
+using dotnet_etcd;
+using Microsoft.Extensions.ServiceDiscovery;
+
+namespace DysonNetwork.Shared.Registry;
+
+/// <summary>
+/// A service endpoint provider that resolves endpoints from an etcd registry.
+/// </summary>
+public class RegistrarServiceEndpointProvider(string serviceName, string servicePart, EtcdClient etcdClient)
+    : IServiceEndpointProvider
+{
+    public ValueTask DisposeAsync()
+    {
+        GC.SuppressFinalize(this);
+        return ValueTask.CompletedTask;
+    }
+
+    /// <summary>
+    /// Populates the endpoints for the service.
+    /// </summary>
+    public async ValueTask PopulateAsync(IServiceEndpointBuilder endpoints, CancellationToken cancellationToken)
+    {
+        var prefix = $"/services/{serviceName}/{servicePart}/";
+
+        // Fetch service instances from etcd.
+        var response = await etcdClient.GetRangeAsync(prefix, cancellationToken: cancellationToken);
+        var instances = response.Kvs.Select(kv => kv.Value.ToStringUtf8());
+
+        foreach (var instance in instances)
+        {
+            // Instances are in "host:port" format.
+            var parts = instance.Split(':', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+            if (parts.Length != 2 || !int.TryParse(parts[1], out var port)) continue;
+            var host = parts[0];
+
+            // Create a DnsEndPoint. The framework will use the original request's scheme (e.g., http, https).
+            endpoints.Endpoints.Add(ServiceEndpoint.Create(new DnsEndPoint(host, port)));
+        }
+    }
+}