Service Mesh in .NET core

This article is part of the Comprehensive Guide to Microservices Architecture in .NET Core, Cloud and Azure series.

Key Benefits

• Traffic Management: Load balancing, routing, and traffic splitting for canary deployments
• Security: Mutual TLS (mTLS) encryption, authentication, and authorization between services
• Observability: Distributed tracing, metrics, and logging for service interactions
• Resilience: Automatic retries, circuit breaking, and timeout policies

Popular Service Mesh Options

Istio

Full-featured, Kubernetes-native service mesh offering comprehensive traffic management, security policies, and observability. Best for complex enterprise environments requiring fine-grained control.

Linkerd

Lightweight and simpler alternative focused on ease of use and minimal resource overhead. Ideal for teams wanting service mesh benefits without operational complexity.

Dapr (Distributed Application Runtime)

Multi-runtime, cloud-agnostic framework that works beyond Kubernetes across VMs, edge, and cloud environments. Provides building blocks for microservices including service invocation, pub/sub, state management, and more.

.NET Aspire: Cloud-Native Orchestration

.NET Aspire is Microsoft's opinionated stack for building observable, production-ready cloud-native applications with .NET 9. While not a traditional service mesh, Aspire provides service discovery, orchestration, and observability features that complement or serve as alternatives to service meshes in certain scenarios.

Key Aspire Features:

• Automatic service discovery and health checks
• Built-in OpenTelemetry integration for distributed tracing
• Local development orchestration with production-ready patterns
• Azure integration for seamless cloud deployment

// .NET Aspire App Host (Program.cs)
var builder = DistributedApplication.CreateBuilder(args);

var cache = builder.AddRedis("cache");
var messaging = builder.AddRabbitMQ("messaging");

var customerService = builder.AddProject<Projects.CustomerService>("customer-service")
    .WithReference(cache);

var orderService = builder.AddProject<Projects.OrderService>("order-service")
    .WithReference(cache)
    .WithReference(messaging)
    .WithReference(customerService); // Automatic service discovery

builder.Build().Run();

Dapr with .NET 9 and C# 13

Dapr integrates seamlessly with .NET 9, leveraging modern C# features and Azure services.

Service Invocation and Pub/Sub

using Dapr.Client;
using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);

// Add Dapr services
builder.Services.AddControllers().AddDapr();
builder.Services.AddDaprClient();

var app = builder.Build();

app.MapControllers();
app.MapSubscribeHandler(); // Dapr pub/sub subscriptions

app.Run();

[ApiController]
[Route("api/[controller]")]
public class OrderController(DaprClient daprClient, IOrderService orderService) : ControllerBase
{
    [HttpPost]
    public async Task<IActionResult> CreateOrder(CreateOrderRequest request)
    {
        // Save order using primary constructor parameter
        var order = await orderService.CreateAsync(request);

        // Publish event via Dapr pub/sub to Azure Service Bus
        await daprClient.PublishEventAsync(
            "servicebus-pubsub",
            "order-events",
            new OrderCreatedEvent 
            { 
                OrderId = order.Id,
                CustomerId = request.CustomerId,
                CreatedAt = DateTime.UtcNow
            });

        // Invoke customer service with resilience (automatic retries)
        var customer = await daprClient.InvokeMethodAsync<Customer>(
            HttpMethod.Get,
            "customer-service",
            $"api/customers/{request.CustomerId}");

        return Ok(new { order, customer });
    }

    // Dapr pub/sub subscription
    [Topic("servicebus-pubsub", "payment-events")]
    [HttpPost("payment-processed")]
    public async Task<IActionResult> HandlePaymentProcessed(PaymentProcessedEvent @event)
    {
        await orderService.UpdatePaymentStatusAsync(@event.OrderId, @event.Status);
        return Ok();
    }
}

// Event records using C# 13 features
public record OrderCreatedEvent
{
    required public string OrderId { get; init; }
    required public string CustomerId { get; init; }
    required public DateTime CreatedAt { get; init; }
}

public record PaymentProcessedEvent(string OrderId, string Status);

State Management with Azure Cosmos DB

public class OrderService(DaprClient daprClient)
{
    private const string StateStoreName = "cosmosdb-state";

    public async Task<Order> CreateAsync(CreateOrderRequest request)
    {
        var order = new Order
        {
            Id = Guid.NewGuid().ToString(),
            CustomerId = request.CustomerId,
            Items = request.Items,
            Status = OrderStatus.Pending
        };

        // Save to Cosmos DB via Dapr state management
        await daprClient.SaveStateAsync(StateStoreName, order.Id, order);

        return order;
    }

    public async Task<Order?> GetAsync(string orderId)
    {
        return await daprClient.GetStateAsync<Order>(StateStoreName, orderId);
    }
}

Azure Integration with Dapr Components

Dapr Component for Azure Service Bus (components/servicebus-pubsub.yaml):

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: servicebus-pubsub
spec:
  type: pubsub.azure.servicebus.topics
  version: v1
  metadata:
  - name: connectionString
    secretKeyRef:
      name: azure-servicebus-connection
  - name: consumerID
    value: "order-service"

Dapr Component for Azure Cosmos DB (components/cosmosdb-state.yaml):

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: cosmosdb-state
spec:
  type: state.azure.cosmosdb
  version: v1
  metadata:
  - name: url
    value: "https://your-account.documents.azure.com:443/"
  - name: masterKey
    secretKeyRef:
      name: cosmosdb-key
  - name: database
    value: "orders-db"
  - name: collection
    value: "orders"

Choosing the Right Approach

• Use .NET Aspire for cloud-native .NET applications requiring orchestration, observability, and Azure integration with minimal setup
• Use Dapr for polyglot microservices, multi-cloud scenarios, or when you need portable building blocks across different hosting environments
• Use Traditional Service Meshes (Istio/Linkerd) for Kubernetes-native applications requiring advanced traffic management and security policies at the infrastructure level

For comprehensive microservices patterns and best practices, visit nova-globen.se.

Additional Resources

• .NET Aspire Documentation
• Dapr Documentation
• Azure Service Mesh Options
• Microservices Architecture Patterns at nova-globen.se

Ready to modernize your microservices architecture? Explore more patterns and tutorials at nova-globen.se.