.NET Tutorial - Your First Microservice

Intro

Install .NET SDK

To start building .NET apps, download and install the .NET SDK.

Check everything installed correctly

dotnet --version

If the installation succeeded, you should see version 8.0.100 or higher outputted:

8.0.100

If everything looks good, select the Continue button below to go to the next step.

Got an error?

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 OpenAPI at https://aka.ms/aspnet/openapi
builder.Services.AddOpenApi();

var app = builder.Build();

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

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");

app.Run();

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

Select the Continue button below to go to the next step.

Run your service

dotnet run

You should see an output similar to the following:

Building...
info: Microsoft.Hosting.Lifetime[14]
Now listening on: http://localhost:5020
info: Microsoft.Hosting.Lifetime[0]
Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
Content root path: C:\Users\Ana\MyMicroservice

Wait for the app to display that it's listening on http://localhost:<port number>, and then open a browser and navigate to http://localhost:<port number>/weatherforecast.

In this example, it showed that it was listening on port 5020, so the following image shows the URL localhost:5020/weatherforecast.

[画像:The API endpoint returns JSON data containing weather forecast information]

Congratulations, you've got a simple service running!

Got an error?

If you receive a message similar to No webpage was found for the web address: http://localhost:5020, ensure you are viewing the Weather Forecast page of your application. The URL should look like http://localhost:5020/weatherforecast and not just http://localhost:5020.

Install Docker

Docker is a platform that enables you to combine an app plus its configuration and dependencies into a single, independently deployable unit called a container.

If you already have Docker installed, make sure it's version 23.0.0 or higher.

Download and install

You'll be asked to register for Docker Store before you can download the installer.

After installing Docker, you may be asked to sign out to finalize installation.

Check that Docker is ready to use

docker --version

If the command runs, displaying some version information, then Docker is successfully installed.

Add Docker metadata

To run with a Docker image, you need a Dockerfile — a text file that contains instructions for how to build your app as a Docker image. A Docker image contains everything needed to run your app as a Docker container.

Return to app directory

cd MyMicroservice

Add a DockerFile

Create a file called Dockerfile with this command:

touch Dockerfile

fsutil file createnew Dockerfile 0

open Dockerfile

start Dockerfile

Replace the content of the Dockerfile to the following in the text editor:

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY MyMicroservice.csproj .
RUN dotnet restore
COPY . .
RUN dotnet publish -c release -o /app

FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY --from=build /app .
ENTRYPOINT ["dotnet", "MyMicroservice.dll"]

Note: Make sure to name the file as Dockerfile and not Dockerfile.txt or some other name.

Optional: Add a .dockerignore file

A .dockerignore file reduces the set of files that are used as part of `docker build`. Fewer files will result in faster builds.

Create a file called .dockerignore file (this is similar to a .gitignore file if you're familiar with those) with this command:

touch .dockerignore

fsutil file createnew .dockerignore 0

open .dockerignore

start .dockerignore

Replace the content of the .dockerignore to the following in the text editor:

Dockerfile
[b|B]in
[O|o]bj

Create Docker image

Run the following command:

docker build -t mymicroservice .

The docker build command uses the Dockerfile to build a Docker image.

• The -t mymicroservice parameter tells it to tag (or name) the image as mymicroservice.
• The final parameter tells it which directory to use to find the Dockerfile (. specifies the current directory).
• This command will download and build all dependencies to create a Docker image and may take some time.

You can run the following command to see a list of all images available on your machine, including the one you just created.

docker images

Run Docker image

You can run your app in a container using the following command:

docker run -it --rm -p 3000:8080 --name mymicroservicecontainer mymicroservice

You can browse to the following URL to access your application running in a container: http://localhost:3000/weatherforecast

[画像:The API endpoint returns JSON data containing weather forecast information]

docker ps

[画像:A list of running docker images with information about each of them.]

Congratulations! You've successfully created a small, independent service that can be deployed and scaled using Docker containers.

These are the fundamental building blocks of microservices.

Got an error?

If you receive a message similar to ERROR: error during connect: this error may indicate that the docker daemon is not running, it may indicate that you need to launch the Docker application. Check that the Docker client is running by running docker run hello-world. This should pull and run the image. For more help, see the Docker documentation for instructions on how to diagnose and fix this issue.

Next steps

Congratulations! You've created a simple service and then ran it in a Docker container.

Now, you can learn how to deploy your microservice to the cloud with our next tutorial.

Tutorial: Deploy microservice to Azure

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