Akka.NET Management and Discovery

┌─────────────────────────────────────────────────────────────┐
│                    Cluster Bootstrap                         │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐     │
│  │  Node 1     │    │  Node 2     │    │  Node 3     │     │
│  │             │    │             │    │             │     │
│  │ Management  │◄──►│ Management  │◄──►│ Management  │     │
│  │ HTTP :8558  │    │ HTTP :8558  │    │ HTTP :8558  │     │
│  └──────┬──────┘    └──────┬──────┘    └──────┬──────┘     │
│         │                  │                  │             │
│         └──────────────────┼──────────────────┘             │
│                            │                                │
│                    ┌───────▼───────┐                        │
│                    │   Discovery   │                        │
│                    │   Provider    │                        │
│                    └───────────────┘                        │
│                            │                                │
└────────────────────────────┼────────────────────────────────┘
                             │
              ┌──────────────┼──────────────┐
              │              │              │
        ┌─────▼─────┐ ┌──────▼─────┐ ┌─────▼──────┐
        │ Kubernetes│ │   Azure    │ │   Config   │
        │    API    │ │   Tables   │ │   (HOCON)  │
        └───────────┘ └────────────┘ └────────────┘

<ItemGroup>
  <!-- Core management -->
  <PackageReference Include="Akka.Management" />
  <PackageReference Include="Akka.Management.Cluster.Bootstrap" />

  <!-- Choose ONE discovery provider -->
  <PackageReference Include="Akka.Discovery.KubernetesApi" />    <!-- For Kubernetes -->
  <PackageReference Include="Akka.Discovery.Azure" />            <!-- For Azure -->
  <PackageReference Include="Akka.Discovery.Config.Hosting" />   <!-- For static config -->
</ItemGroup>

public static class AkkaConfiguration
{
    public static IServiceCollection ConfigureAkka(
        this IServiceCollection services,
        Action<AkkaConfigurationBuilder, IServiceProvider>? additionalConfig = null)
    {
        services.AddOptions<AkkaSettings>()
            .BindConfiguration("AkkaSettings")
            .ValidateDataAnnotations()
            .ValidateOnStart();

        return services.AddAkka("MySystem", (builder, sp) =>
        {
            var settings = sp.GetRequiredService<IOptions<AkkaSettings>>().Value;
            var configuration = sp.GetRequiredService<IConfiguration>();

            ConfigureNetwork(builder, settings, configuration);
            ConfigureHealthChecks(builder);

            additionalConfig?.Invoke(builder, sp);
        });
    }

    private static void ConfigureNetwork(
        AkkaConfigurationBuilder builder,
        AkkaSettings settings,
        IConfiguration configuration)
    {
        if (settings.ExecutionMode == AkkaExecutionMode.LocalTest)
            return;

        builder.WithRemoting(settings.RemoteOptions);

        if (settings.ClusterBootstrapOptions.Enabled)
            ConfigureAkkaManagement(builder, settings, configuration);
        else
            builder.WithClustering(settings.ClusterOptions);
    }
}

private static void ConfigureAkkaManagement(
    AkkaConfigurationBuilder builder,
    AkkaSettings settings,
    IConfiguration configuration)
{
    var mgmtOptions = settings.AkkaManagementOptions;
    var bootstrapOptions = settings.ClusterBootstrapOptions;

    // IMPORTANT: Clear seed nodes when using Akka.Management
    settings.ClusterOptions.SeedNodes = [];

    builder
        .WithClustering(settings.ClusterOptions)
        .WithAkkaManagement(setup =>
        {
            setup.Http.HostName = mgmtOptions.HostName;
            setup.Http.Port = mgmtOptions.Port;
            setup.Http.BindHostName = "0.0.0.0";
            setup.Http.BindPort = mgmtOptions.Port;
        })
        .WithClusterBootstrap(options =>
        {
            options.ContactPointDiscovery.ServiceName = bootstrapOptions.ServiceName;
            options.ContactPointDiscovery.PortName = bootstrapOptions.PortName;
            options.ContactPointDiscovery.RequiredContactPointsNr = bootstrapOptions.RequiredContactPointsNr;
            options.ContactPointDiscovery.Interval = bootstrapOptions.ContactPointProbingInterval;
            options.ContactPointDiscovery.StableMargin = bootstrapOptions.StableMargin;
            options.ContactPointDiscovery.ContactWithAllContactPoints = bootstrapOptions.ContactWithAllContactPoints;
            options.ContactPoint.FilterOnFallbackPort = bootstrapOptions.FilterOnFallbackPort;
            options.ContactPoint.ProbeInterval = bootstrapOptions.BootstrapperDiscoveryPingInterval;
        });

    // Configure the discovery provider
    ConfigureDiscovery(builder, settings, configuration);
}

// Register Akka health checks
builder.Services.AddHealthChecks();

// In Akka configuration
builder
    .WithActorSystemLivenessCheck()     // Adds "akka-liveness" health check
    .WithAkkaClusterReadinessCheck();   // Adds "akka-cluster-readiness" health check

// Map endpoints
app.MapHealthChecks("/health/live", new HealthCheckOptions
{
    Predicate = check => check.Tags.Contains("liveness")
});

app.MapHealthChecks("/health/ready", new HealthCheckOptions
{
    Predicate = check => check.Tags.Contains("readiness")
});