Monq.Core.MicroserviceAddressing 0.1.0

Monq.Core.MicroserviceAddressing

Monq.Core.MicroserviceAddressing provides shared address resolution policies for MONQ microservices. It creates logical addresses and indicates whether a client must connect directly or enable client-side service discovery. DNS lookup, HTTP endpoint selection, and gRPC balancing remain the responsibility of the corresponding client libraries.

Built-in conventions

The namespace is derived from IHostEnvironment.EnvironmentName and normalized to lowercase. Pass a port to override a strategy default.

Registration

The built-in fallback is Kubernetes ClusterIP:

builder.Services.AddMicroserviceAddressing();

HTTP and gRPC can use different policies:

builder.Host
    .UseHttpMicroserviceAddressResolver(
        new KubernetesClusterIpAddressResolver())
    .UseGrpcMicroserviceAddressResolver(
        new KubernetesServiceDiscoveryAddressResolver());

Use one common resolver when a library should provide protocol-specific defaults that an application can replace with a single common override:

builder.Host.UseMicroserviceAddressResolver(
    new ProtocolMicroserviceAddressResolver(
        httpResolver: new KubernetesClusterIpAddressResolver(),
        grpcResolver: new KubernetesServiceDiscoveryAddressResolver()));

A library that provides a fallback policy can call TryUseMicroserviceAddressResolver instead: it selects the default resolver only when none was selected before, so an earlier application selection is preserved.

Resolve an address from another library or application component:

public sealed class EndpointConsumer(IMicroserviceAddressProvider addresses)
{
    public Uri Resolve(string applicationName, int port) =>
        addresses.Resolve(
            applicationName,
            MicroserviceProtocol.Http,
            port).Address;
}

Resolver precedence is:

1. Resolver supplied for a particular client.
2. HTTP or gRPC resolver.
3. Default resolver.
4. Built-in Kubernetes ClusterIP resolver.

Custom policy

Implement IMicroserviceAddressResolver and replace only the required scope:

public sealed class ProductAddressResolver : IMicroserviceAddressResolver
{
    public ResolvedMicroserviceAddress Resolve(MicroserviceAddressContext context)
    {
        var address = context.Environment.IsDevelopment()
            ? new Uri(context.Configuration["BaseUri"]!)
            : new Uri(
                $"http://{context.TargetApplicationName}.custom.svc.cluster.local:{context.PortOverride ?? 80}");

        return new(address);
    }
}

builder.Host.UseHttpMicroserviceAddressResolver(
    new ProductAddressResolver());

The default, HTTP, and gRPC resolvers can be registered as an instance or as a factory using the final HostBuilderContext. The selected resolver instance is shared by client registration and the runtime IMicroserviceAddressProvider.