.Net Reverse Proxy with YARP

How about creating a reverse proxy with .NET Core or .NET 5?
If you had to do that once, you should know YARP!

YARP is a Reverse Proxy project that Microsoft is working on. For now, it is in preview, but it's an easier way to create a simple reverse proxy for our applications.

How does it work?

In this GitHub, you can find a sample that presents how we can use YARP:

• ProductA: the API that can only list "products".
• ProductB: the API that can only insert new "products"
• Proxy: the reverse proxy that will redirect each request to APIs: ProductA and ProductB.

Basically, what we need to create a simple Reverse Proxy is to set Routes and Clusters in appSettings.json from the Proxy project.

For each Route we should:

• Define how we want to expose an API.
• Set the API original path that Reverse Proxy must redirect our calls.
• Define which Cluster is associated with API.

For Cluster settings, we should define the host address for each API exposed by YARP. When we call a route, YARP will call the original path concatenated with the API address defined in the Cluster section.

See below a sample of YARP settings:

	"ReverseProxy": {
	"Routes": [
	{
	"RouteId": "produto-v1-listarProduto",
	"ClusterId": "produto-v1",
	"Match": {
	"Path": "/produto",
	"Methods": [
	"GET"
	]
	},
	"Transforms": [
	{
	"PathSet": "/v1/product"
	}
	]
	},
	{
	"RouteId": "produto-v2-incluirProduto",
	"ClusterId": "produto-v2",
	"Match": {
	"Path": "/produto",
	"Methods": [
	"POST"
	]
	},
	"Transforms": [
	{
	"PathPattern": "v2/product"
	}
	]
	},
	],
	"Clusters": {
	"produto-v1": {
	"Destinations": {
	"produto-v1-dst": {
	"Address": "http://localhost:5010"
	}
	}
	},
	"produto-v2": {
	"Destinations": {
	"produto-v2-dst": {
	"Address": "http://localhost:5011"
	}
	}
	}
	}
	}

view raw yarp-settings-json.sh hosted with ❤ by GitHub

Finally, in our startup class, we need to register YARP and load all settings.

	services.AddReverseProxy()
	.LoadFromConfig(_configuration.GetSection("ReverseProxy"));

view raw yarp-service-load.sh hosted with ❤ by GitHub

After that, we need to add each route defined in our Proxy appSettings.json to endpoint collections.

	app.UseEndpoints(endpoints =>
	{
	endpoints.MapReverseProxy();
	});

view raw yarp-middleware.sh hosted with ❤ by GitHub

It's done! Now we can call our APIs through our reverse proxy. Try to get a list of products by this endpoint: http://localhost:5000/produto

As presented above, when we call a route from our Proxy, the request is redirected to the original API, in this case to ProductA API.