Using YARP to create a reverse proxy server

So far I’ve always used ProxyKit to create a reverse proxy in ASP.NET Core. But with the announcement of Yarp, it is time to try this alternative…

• I created a new ASP.NET Core “empty” project:

dotnet new web -n ProxyTest -f netcoreapp3.1
The template "ASP.NET Core Empty" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on ProxyTest\ProxyTest.csproj...
  Restore completed in 278,54 ms for C:\Projects\test\yarptest\ProxyTest\ProxyTest.csproj.

Restore succeeded.

• Next step is to reference the Microsoft.ReverseProxy preview nuget package:

<ItemGroup> 
  <PackageReference Include="Microsoft.ReverseProxy" Version="1.0.0-preview.1.*" /> 
</ItemGroup>

• Now it is time to update our Startup.cs. This is what I had when using Proxykit:

	public void ConfigureServices(IServiceCollection services)
	{
	services.AddProxy();
	}
	// Forward HTTP requests to upstream-server:5001:
	public void Configure(IApplicationBuilder app)
	{
	app.RunProxy(context => context
	.ForwardTo("http://upstream-server:5001/")
	.AddXForwardedHeaders()
	.Send());
	}

view raw StartupProxyKit.cs hosted with ❤ by GitHub

• And here is the updated Startup.cs after switching to Yarp:

	public Startup(IConfiguration configuration)
	{
	Configuration = configuration;
	}
	public void ConfigureServices(IServiceCollection services)
	{
	services.AddReverseProxy()
	.LoadFromConfig(Configuration.GetSection("ReverseProxy"));
	}
	// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
	public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
	{
	app.UseRouting();
	app.UseEndpoints(endpoints =>
	{
	endpoints.MapReverseProxy(proxyPipeline =>
	{
	proxyPipeline.UseProxyLoadBalancing();
	});
	});
	}

view raw StartupYarp.cs hosted with ❤ by GitHub

• In Yarp everything is handled through configuration right now, so the real magic is there:

	{
	"Logging": {
	"LogLevel": {
	"Default": "Information",
	"Microsoft": "Warning",
	"Microsoft.Hosting.Lifetime": "Information"
	}
	},
	"AllowedHosts": "*",
	"ReverseProxy": {
	"Routes": [
	{
	"RouteId": "app1",
	"BackendId": "backend1",
	"Match": {
	"Host": "localhost"
	}
	}
	],
	"Backends": {
	"backend1": {
	"Destinations": {
	"backend1_destination1": {
	"Address": "http://upstream-server:5001/"
	}
	}
	}
	}
	}
	}

view raw appsettingsyarp.json hosted with ❤ by GitHub

I'm curious on how this will evolve in the future...