.NET Aspire Dapr integration

Distributed Application Runtime (Dapr) offers developer APIs that serve as a conduit for interacting with other services and dependencies and abstract the application from the specifics of those services and dependencies. Dapr and .NET Aspire can work together to improve your local development experience. By using Dapr with .NET Aspire, you can focus on writing and implementing .NET-based distributed applications instead of local on-boarding.

In this guide, you'll learn how to take advantage of Dapr's abstraction and .NET Aspire's opinionated configuration of cloud technologies to build simple, portable, resilient, and secured microservices at scale.

Comparing .NET Aspire and Dapr

At first sight Dapr and .NET Aspire may look like they have overlapping functionality, and they do. However, they take different approaches. .NET Aspire is opinionated on how to build distributed applications on a cloud platform and focuses on improving the local development experience. Dapr is a runtime that abstracts away the common complexities of the underlying cloud platform both during development and in production. It relies on sidecars to provide abstractions for things like configuration, secret management, and messaging. The underlying technology can be easily switched out through configuration files, while your code does not need to change.

.NET Aspire makes setting up and debugging Dapr applications easier by providing a straightforward API to configure Dapr sidecars, and by exposing the sidecars as resources in the dashboard.

Explore Dapr components with .NET Aspire

Dapr provides many built-in components, and when you use Dapr with .NET Aspire you can easily explore and configure these components. Don't confuse these components with .NET Aspire integrations. For example, consider the following:

• Dapr—State stores: Call AddDaprStateStore to add a configured state store to your .NET Aspire project.
• Dapr—Pub Sub: Call AddDaprPubSub to add a configured pub sub to your .NET Aspire project.
• Dapr—Components: Call AddDaprComponent to add a configured integration to your .NET Aspire project.

Install Dapr

This integration requires Dapr version 1.13 or later. To install Dapr, see Install the Dapr CLI. After installing the Dapr CLI, run the dapr init, as described in Initialize Dapr in your local environment.

Unable to locate the Dapr CLI.

Hosting integration

In your .NET Aspire solution, to integrate Dapr and access its types and APIs, add the 📦 Aspire.Hosting.Dapr NuGet package in the app host project.

dotnet add package Aspire.Hosting.Dapr

<PackageReference Include="Aspire.Hosting.Dapr"
                  Version="*" />

For more information, see dotnet add package or Manage package dependencies in .NET applications.

Add Dapr sidecar to .NET Aspire resources

Dapr uses the sidecar pattern. The Dapr sidecar runs alongside your app as a lightweight, portable, and stateless HTTP server that listens for incoming HTTP requests from your app.

To add a sidecar to a .NET Aspire resource, call the WithDaprSidecar method on it. The appId parameter is the unique identifier for the Dapr application, but it's optional. If you don't provide an appId, the parent resource name is used instead.

using Aspire.Hosting.Dapr;

var builder = DistributedApplication.CreateBuilder(args);

var apiService = builder
    .AddProject<Projects.Dapr_ApiService>("apiservice")
    .WithDaprSidecar();

Configure Dapr sidecars

The WithDaprSidecar method offers overloads to configure your Dapr sidecar options like AppId and various ports. In the following example, the Dapr sidecar is configured with specific ports for GRPC, HTTP, metrics, and a specific app ID.

DaprSidecarOptions sidecarOptions = new()
{
    AppId = "FirstSidecar",
    DaprGrpcPort = 50001,
    DaprHttpPort = 3500,
    MetricsPort = 9090
};

builder.AddProject<Projects.Dapr_Web>("webfrontend")
    .WithExternalHttpEndpoints()
    .WithReference(apiService)
    .WithDaprSidecar(sidecarOptions);

Complete Dapr app host example

Putting everything together, consider the following example of a .NET Aspire app host project that includes:

• A backend API service that declares a Dapr sidecar with defaults.
• A web frontend project that declares a Dapr sidecar with specific options, such as explict ports.

using Aspire.Hosting.Dapr;

var builder = DistributedApplication.CreateBuilder(args);

var apiService = builder
    .AddProject<Projects.Dapr_ApiService>("apiservice")
    .WithDaprSidecar();

DaprSidecarOptions sidecarOptions = new()
{
    AppId = "FirstSidecar",
    DaprGrpcPort = 50001,
    DaprHttpPort = 3500,
    MetricsPort = 9090
};

builder.AddProject<Projects.Dapr_Web>("webfrontend")
    .WithExternalHttpEndpoints()
    .WithReference(apiService)
    .WithDaprSidecar(sidecarOptions);

builder.Build().Run();

When you start the .NET Aspire solution, the dashboard shows the Dapr sidecar as a resource, with its status and logs.

Use Dapr sidecars in consuming .NET Aspire projects

To use Dapr APIs from .NET Aspire resources, you can use the 📦 Dapr.AspNetCore/ NuGet package. The Dapr SDK provides a set of APIs to interact with Dapr sidecars.

dotnet add package Dapr.AspNetCore

<PackageReference Include="Dapr.AspNetCore"
                  Version="*" />

Add Dapr client

Once installed into an ASP.NET Core project, the SDK can be added to the service builder.

builder.Services.AddDaprClient();

Invoke Dapr methods

An instance of DaprClient can now be injected into your services to interact with the Dapr sidecar through the Dapr SDK:

using Dapr.Client;

namespace Dapr.Web;

public class WeatherApiClient(DaprClient client)
{
    public async Task<WeatherForecast[]> GetWeatherAsync(
        int maxItems = 10, CancellationToken cancellationToken = default)
    {
        List<WeatherForecast>? forecasts =
            await client.InvokeMethodAsync<List<WeatherForecast>>(
                HttpMethod.Get,
                "apiservice",
                "weatherforecast",
                cancellationToken);

        return forecasts?.Take(maxItems)?.ToArray() ?? [];
    }
}

public record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

InvokeMethodAsync is the method that sends an HTTP request to the Dapr sidecar. It is a generic method that takes:

• An HTTP verb.
• The Dapr app ID of the service to call.
• The method name.
• A cancellation token.

Depending on the HTTP verb, it can also take a request body and headers. The generic type parameter is the type of the response body.

The full Program.cs file for the frontend project shows:

• The Dapr client being added to the service builder.
• The WeatherApiClient class that uses the Dapr client to call the backend service.

using Dapr.Web;
using Dapr.Web.Components;

var builder = WebApplication.CreateBuilder(args);

// Add service defaults & Aspire components.
builder.AddServiceDefaults();

// Add services to the container.
builder.Services.AddRazorComponents()
    .AddInteractiveServerComponents();

builder.Services.AddOutputCache();

builder.Services.AddDaprClient();

builder.Services.AddTransient<WeatherApiClient>();

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error", createScopeForErrors: true);
    app.UseHsts();
}

app.UseHttpsRedirection();

app.UseStaticFiles();
app.UseAntiforgery();

app.UseOutputCache();

app.MapRazorComponents<App>()
    .AddInteractiveServerRenderMode();

app.MapDefaultEndpoints();

app.Run();

For example, in a Blazor project, you can inject the WeatherApiClient class into a razor page and use it to call the backend service:

@page "/weather"
@attribute [StreamRendering(true)]
@attribute [OutputCache(Duration = 5)]

@inject WeatherApiClient WeatherApi

<PageTitle>Weather</PageTitle>

<h1>Weather</h1>

<p>This component demonstrates showing data loaded from a backend API service.</p>

@if (forecasts == null)
{
    <p><em>Loading...</em></p>
}
else
{
    <table class="table">
        <thead>
            <tr>
                <th>Date</th>
                <th>Temp. (C)</th>
                <th>Temp. (F)</th>
                <th>Summary</th>
            </tr>
        </thead>
        <tbody>
            @foreach (var forecast in forecasts)
            {
                <tr>
                    <td>@forecast.Date.ToShortDateString()</td>
                    <td>@forecast.TemperatureC</td>
                    <td>@forecast.TemperatureF</td>
                    <td>@forecast.Summary</td>
                </tr>
            }
        </tbody>
    </table>
}

@code {
    private WeatherForecast[]? forecasts;

    protected override async Task OnInitializedAsync()
    {
        forecasts = await WeatherApi.GetWeatherAsync();
    }
}

When the Dapr SDK is used, the Dapr sidecar is called over HTTP. The Dapr sidecar then forwards the request to the target service. While the target service runs in a separate process from the sidecar, the integration related to the service runs in the Dapr sidecar and is responsible for service discovery and routing the request to the target service.

Next steps

• Dapr
• Dapr documentation
• Dapr GitHub repo
• .NET Aspire Dapr sample app
• .NET Aspire integrations
• .NET Aspire GitHub repo