Creating Windows and Linux background services in dotnet core 3.0/3.1

There are times when you need an application to just sit there in the background and deal with the same repetitive task over and over again.

In dotnet core 3.0, a new type of template was introduced, “Worker Service”, which is a very easy way of creating Windows Services and Linux Daemons.

The Basics

The new “worker” template can be accessed in one of two ways:

  1. via the command line
mkdir myNewWorker
cd myNewWorker
dotnet new worker
  1. via Visual Studio

Visual Studio new background worker project example

Either way, you end up with the same basic template to start with, which is your Startup class, and your Worker class.

The Startup Class

The startup class is your entry point to the executable In the initial template, we are

public static IHostBuilder CreateHostBuilder(string[] args)
{
    return Host.CreateDefaultBuilder(args)
        .ConfigureServices((hostContext, services) =>
        {
            services.AddHostedService<Worker>();
        });
}

The first thing we need to do is add the generic host library nuget package Microsoft.Extensions.Hosting and switch the SDK to the worker SDK.

You can do this by opening up your csproj file and making the following changes:

<Project Sdk="Microsoft.NET.Sdk.Worker">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Hosting" />
  </ItemGroup>
</Project>

Next, we need to add the following lines to our CreateHostBuilder.

public static IHostBuilder CreateHostBuilder(string[] args)
{
    return Host.CreateDefaultBuilder(args)
        .UseSystemd()
        .UseWindowsService()
        .ConfigureServices((hostContext, services) =>
        {
            services.AddHostedService<Worker>();
        });
}

The Worker class

Lastly, we can create our background service worker class, which is executed asynchronously, has logging, and has configuration built in too.

    public class Worker : BackgroundService
    {
        private readonly ILogger<Worker> _logger;
        private readonly IConfiguration configuration;

        public Worker(ILogger<Worker> logger, IConfiguration configuration)
        {
            _logger = logger;
            this.configuration = configuration;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                await Task.Delay(1000, stoppingToken);
            }
        }
    }

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