3-dashboard-apphost.md

Dashboard & Orchestration with .NET Aspire App Host

.NET Aspire provides APIs for modeling resources and dependencies within your distributed application. In addition to these APIs, there's tooling that enables some compelling scenarios. The orchestrator is intended for local development purposes.

Before continuing, consider some common terminology used in .NET Aspire:

• App model: A collection of resources that make up your distributed application (DistributedApplication). For a more formal definition, see Define the app model.
• App host/Orchestrator project: The .NET project that defines and orchestrates the app model, named with the *.AppHost suffix (by convention).
• Resource: A resource represents a part of an application whether it be a .NET project, container, or executable, or some other resource like a database, cache, or cloud service (such as a storage service).
• Reference: A reference defines a connection between resources, expressed as a dependency using the WithReference API. For more information, see Reference resources.

Create App Host Project

Visual Studio & Visual Studio Code

1. Add a new project to the solution called AppHost:

   • Right-click on the solution and select Add > New Project.
   • Select the .NET Aspire App Host project template.
   • Name the project AppHost.
   • Click Next > Create.

   Visual Studio

   Visual Studio Code

Command Line

1. Create a new project using the dotnet new aspire-apphost command:

   dotnet new aspire-apphost -n AppHost

Add Project References

1. Add a reference to the Api and MyWeatherHub projects in the new AppHost project:

   • Right-click on the AppHost project and select Add > Reference.

   • Check the Api and MyWeatherHub projects and click OK.

     Pro Tip: In Visual Studio 2022, you can drag and drop the project onto another project to add a reference.

2. When these references are added, helper classes are automatically generated to help add them to the app model in the App Host.

Orchestrate the Application

1. In the AppHost project, update the Program.cs file, adding the following line immediately after the var builder = DistributedApplication.CreateBuilder(args); line:

   var api = builder.AddProject<Projects.Api>("api");
   
   var web = builder.AddProject<Projects.MyWeatherHub>("myweatherhub");

Run the application

1. Set the AppHost project as the startup project in Visual Studio by right clicking on the AppHost and clicking Set Default Project.

2. If you are using Visual Studio Code open the launch.json and replace all of the contents with the following:

   {
       "version": "0.2.0",
       "configurations": [
           {
               "name": "Run AppHost",
               "type": "dotnet",
               "request": "launch",
               "projectPath": "${workspaceFolder}\\AppHost\\AppHost.csproj"
           }
       ]
   }

3. Run the App Host using the Run and Debug panel in Visual Studio Code or Visual Studio.

4. The .NET Aspire Dashboard will open in your default browser and display the resources and dependencies of your application.

   

5. Open the weather page by clicking the Endpoint for the MyWeatherHub project resource which will be https://localhost:7274.

6. Notice that both the Api and MyWeatherHub projects are running and can communicate with each other the same way as before using configuration settings.

7. Back on the Aspire Dashboard, click on the View Logs button to see the console logs from the Api and MyWeatherHub projects.

8. Select the Traces tab and select View on a trace where the API is being called.

   

9. Explore the Metrics tab to see the metrics for the Api and MyWeatherHub projects.

   

Create an error

1. Open the Structured tab on the dashboard.

2. Set the Level to Error and notice that no errors appear

3. On the MyWeatherApp website, click on several different cities to generate errors. Usually, clicking on 5 different cities will generate at least one error.

4. After generating the errors, the Structured tab will automatically update on the dashboard and display the errors.

   

5. Click on the Trace or the Details to see the error message and stack trace.

Next: Module #4: Service Discovery