MSDN Documentation

ASP.NET Core Hosting

This document provides an in-depth guide to hosting ASP.NET Core applications. Understanding hosting is crucial for deploying your web applications reliably and efficiently.

What is Hosting?

Hosting an ASP.NET Core application involves making it accessible to users over the internet or a private network. This typically involves a web server (like IIS, Nginx, or Apache) and a runtime environment that executes your application code. ASP.NET Core is designed to be cross-platform and flexible, supporting various hosting models.

Hosting Models

ASP.NET Core applications can be hosted in a few primary ways:

• In-process hosting: The ASP.NET Core Module (ANCM) directly hosts the application within the IIS worker process. This model offers performance benefits by eliminating the network hop between IIS and the Kestrel server.
• Out-of-process hosting: Kestrel, the cross-platform web server included with ASP.NET Core, listens for requests and forwards them to your application. A reverse proxy server (like IIS, Nginx, or Apache) can then forward external requests to Kestrel. This is the default and recommended model for most scenarios.

Key Hosting Concepts

Several components and configurations are essential for successful hosting:

Kestrel Web Server

Kestrel is the default, cross-platform web server for ASP.NET Core. It's lightweight, high-performance, and can be self-hosted or used behind a reverse proxy. You configure Kestrel in your application's startup code, typically in Program.cs.

public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

ASP.NET Core Module (ANCM)

For hosting within IIS on Windows, the ASP.NET Core Module (ANCM) is a native IIS module that manages the lifetime of your ASP.NET Core application. It handles request forwarding, application recycling, and logging.

Reverse Proxy Servers

Reverse proxy servers like Nginx, Apache, or IIS (acting as a reverse proxy) can improve performance, security, and scalability. They can handle SSL termination, load balancing, and static file serving, forwarding dynamic requests to your ASP.NET Core application's Kestrel server.

Environment Variables and Configuration

Hosting environments often use environment variables to configure application settings. ASP.NET Core's configuration system can read these variables, allowing for flexible deployment across different platforms and environments (e.g., Development, Staging, Production).

Deployment Scenarios

This section outlines common deployment patterns:

• Self-contained deployment: The .NET runtime is included with your application.
• Framework-dependent deployment: Your application relies on a globally installed .NET runtime.
• Containerization (Docker): Packaging your application within Docker containers for consistent deployment across any environment.

For detailed deployment guides, refer to the ASP.NET Core Deployment documentation.

Further Reading

• ASP.NET Core Deployment
• Official ASP.NET Core Hosting Documentation