Demystifying CORS in .NET 6.0 Minimal APIs

Introduction

Cross-Origin Resource Sharing, commonly known as CORS, plays a pivotal role in contemporary web development by empowering servers to regulate the domains permitted to access their resources. This blog post delves into the management of CORS in .NET 6.0 Minimal APIs, exploring the simplicity and adaptability it introduces.

Understanding Minimal APIs

In .NET 6.0, Minimal APIs present a more streamlined approach to constructing web APIs with reduced complexity. They boast a concise syntax, simplifying code composition and maintenance while retaining the robust capabilities and flexibility inherent in the ASP.NET Core framework.

Implementation of CORS in Minimal APIs

Enabling CORS within Minimal APIs proves remarkably straightforward. By navigating to your Program.cs file, where web application configuration takes place, you can seamlessly incorporate CORS settings directly into the builder.

Example Code

var builder = WebApplication.CreateBuilder(args);

// Configure CORS
builder.Services.AddCors(options =>
{
    options.AddPolicy("AllowAll", builder =>
    {
        builder.AllowAnyOrigin()
               .AllowAnyHeader()
               .AllowAnyMethod();
    });
});

var app = builder.Build();

// Use CORS
app.UseCors("AllowAll");

// Define your endpoints
app.MapGet("/", () => "Hello, Minimal API!");

app.Run();

This example sets up a CORS policy named "AllowAll" that allows any origin, header, and method. The policy is then applied using UseCors in the application's middleware pipeline.

Managing CORS Preflight Requests

In .NET 6.0 Minimal APIs, CORS preflight requests are managed automatically. When the browser initiates an HTTP OPTIONS request to assess the server's CORS capabilities, the Minimal API promptly issues a fitting response.

Tailoring CORS Policies

The customization of CORS policies within Minimal APIs is highly adaptable. Crafting specific policies for distinct controllers or actions, aligned with the needs of your application, can be effortlessly accomplished.

Example Code

app.MapGet("/public", () => "Public Data")
   .WithCors("AllowAll");

app.MapGet("/restricted", () => "Restricted Data")
   .WithCors("AllowSpecificOrigin");

Conclusion

Within .NET 6.0 Minimal APIs, CORS configuration undergoes simplification, aligning seamlessly with the framework's commitment to minimizing boilerplate code. Grasping the process of enabling CORS and tailoring policies guarantees the secure accessibility of your Minimal API from various domains. Embrace the streamlined nature of Minimal APIs while upholding best practices in secure web development.