.NET Tutorial - Your First Microservice

Create your service

dotnet new webapi -o MyMicroservice --no-https

Then, navigate to the new directory created by the previous command:

cd MyMicroservice

What do these commands mean?

The dotnet command creates a new application of type webapi (that's a REST API endpoint).

• The -o parameter creates a directory named MyMicroservice where your app is stored.
• The --no-https flag creates an app that will run without an HTTPS certificate, to keep things simple for deployment.

The cd MyMicroservice command puts you into the newly created app directory.

The generated code

Several files were created in the MyMicroservice directory, to give you a simple service that is ready to run, including the following files:

• Program.cs is the entry point file and contains all the settings and configuration that are loaded when the app starts and has code for a simple API that returns the weather forecast for the next five days. It also starts the application.
• MyMycroservice.http is used for testing ASP.NET Core projects.
• MyMicroservice.csproj defines the version of .NET the app is targeting, what libraries the project references, etc.
• The launchSettings.json file inside the Properties directory defines different profile settings for the local development environment. A port number ranging between 5000-5300 is automatically assigned at project creation and saved on this file.

The following code shows the contents of the Program.cs file:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};

app.MapGet("/weatherforecast", () =>
{
    var forecast =  Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return forecast;
})
.WithName("GetWeatherForecast")
.WithOpenApi();

app.Run();

record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

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