Konfigo.Client 0.0.4

Konfigo.Client

Client SDK for the Konfigo Realtime Config service. It plugs configuration classes annotated with the attributes from Konfigo.Abstraction into the standard IConfiguration / IOptions<T> pipeline and applies updates at runtime without restarting the host.

How it works

1. At host startup AddRealtimeConfig() on IConfigurationBuilder reads the RealtimeConfigOptions section and, if the SDK is enabled, registers a gRPC-backed configuration source. The source pulls the initial snapshot and exposes it through IConfiguration.
2. AddRealtimeConfig() on IServiceCollection registers a hosted service that:
   • Uses reflection to find classes annotated with [ConfigGroup], describes their schema, and registers a version on the backend (or reuses an existing one if the same version is already known — concurrent startups are guarded by a distributed lock).
   • Subscribes to the update event stream and applies events to the provider. Each key carries a Generation; stale events are ignored to avoid races on reconnect.
   • Binds each group to IOptions<T> under the key from ConfigGroupAttribute.Key.

IOptionsMonitor<T> propagates updates correctly — OnChange handlers fire after the provider calls OnReload().

Setup

// Program.cs

var builder = WebApplication.CreateBuilder(args);

builder.Configuration.AddRealtimeConfig();
builder.Services.AddRealtimeConfig();

var app = builder.Build();
app.Run();

Minimal appsettings.json:

{
  "RealtimeConfigOptions": {
    "IsEnabled": true,
    "ServiceId": "orders",
    "Version": "1.0.0",
    "Url": "https://realtime-config.internal",
    "PollingInterval": "00:00:05"
  }
}

Tuning the version registration lock

Version registration is guarded by a distributed lock so that concurrent instances of the same service do not register the same version twice. The lock-acquisition timeout defaults to 30 seconds and can be overridden via the VersionServiceOptions section:

{
  "VersionServiceOptions": {
    "LockTimeout": "00:01:00"
  }
}

Declaring configuration classes

Classes and properties are declared with the attributes from Konfigo.Abstraction:

using Konfigo.Abstraction.Attributes;

[ConfigGroup(key: "Payments", groupName: "Payments", description: "Payment gateway")]
public sealed class PaymentsOptions
{
    [ConfigKey(description: "Payment provider", defaultValue: "Stripe")]
    public string Provider { get; set; } = string.Empty;

    [ConfigKey(description: "Request timeout", defaultValue: "00:00:30")]
    public TimeSpan Timeout { get; set; }
}

The class is bound automatically — no explicit IOptions<PaymentsOptions> registration is required. Consumption is standard:

public sealed class CheckoutService(IOptionsMonitor<PaymentsOptions> options)
{
    public Task ChargeAsync()
    {
        var snapshot = options.CurrentValue;
        // ...
    }
}

Public API

Failure modes

• When IsEnabled = false the hosted service parks on Task.Delay(Infinite) and stays idle.
• If no class annotated with [ConfigGroup] is found, the service logs a warning and does not start. This is a safe no-op rather than a host crash.
• When the subscription stream drops, the service waits for PollingInterval and re-establishes the subscription. The local timestamp is preserved so it resumes from where it left off after a reconnect.
• Events with Generation == 1 are treated as the initial state and do not overwrite data already loaded via the initial snapshot.

Related packages

• Konfigo.Abstraction — the ConfigGroup / ConfigKey attributes.