Host ASP.NET Core in a Windows Service

By Luke Latham and Tom Dykstra

An ASP.NET Core app can be hosted on Windows as a Windows Service without using IIS. When hosted as a Windows Service, the app automatically starts after server reboots.

View or download sample code (how to download)

Prerequisites

Worker Service template

The ASP.NET Core Worker Service template provides a starting point for writing long running service apps. To use the template as a basis for a Windows Service app:

  1. Create a Worker Service app from the .NET Core template.
  2. Follow the guidance in the App configuration section to update the Worker Service app so that it can run as a Windows Service.
  1. Create a new project.
  2. Select ASP.NET Core Web Application. Select Next.
  3. Provide a project name in the Project name field or accept the default project name. Select Create.
  4. In the Create a new ASP.NET Core Web Application dialog, confirm that .NET Core and ASP.NET Core 3.0 are selected.
  5. Select the Worker Service template. Select Create.

App configuration

IHostBuilder.UseWindowsService, provided by the Microsoft.Extensions.Hosting.WindowsServices package, is called when building the host. If the app is running as a Windows Service, the method:

  • Sets the host lifetime to WindowsServiceLifetime.
  • Sets the content root.
  • Enables logging to the event log with the application name as the default source name.
    • The log level can be configured using the Logging:LogLevel:Default key in the appsettings.Production.json file.
    • Only administrators can create new event sources. When an event source can't be created using the application name, a warning is logged to the Application source and event logs are disabled.
public class Program
{
    public static async Task Main(string[] args)
    {
        await CreateHostBuilder(args).Build().RunAsync();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .UseWindowsService()
            .ConfigureAppConfiguration((context, config) =>
            {
                // Configure the app here.
            })
            .ConfigureServices((hostContext, services) =>
            {
                services.AddHostedService<ServiceA>();
                services.AddHostedService<ServiceB>();
            })
            // Only required if the service responds to requests.
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

The app requires package references for Microsoft.AspNetCore.Hosting.WindowsServices and Microsoft.Extensions.Logging.EventLog.

To test and debug when running outside of a service, add code to determine if the app is running as a service or a console app. Inspect if the debugger is attached or a --console switch is present. If either condition is true (the app isn't run as a service), call Run. If the conditions are false (the app is run as a service):

Because the Command-line Configuration Provider requires name-value pairs for command-line arguments, the --console switch is removed from the arguments before CreateDefaultBuilder receives the arguments.

To write to the Windows Event Log, add the EventLog provider to ConfigureLogging. Set the logging level with the Logging:LogLevel:Default key in the appsettings.Production.json file.

In the following example from the sample app, RunAsCustomService is called instead of RunAsService in order to handle lifetime events within the app. For more information, see the Handle starting and stopping events section.

public class Program
{
    public static void Main(string[] args)
    {
        var isService = !(Debugger.IsAttached || args.Contains("--console"));
        
        if (isService)
        {
            var pathToExe = Process.GetCurrentProcess().MainModule.FileName;
            var pathToContentRoot = Path.GetDirectoryName(pathToExe);
            Directory.SetCurrentDirectory(pathToContentRoot);
        }

        var builder = CreateWebHostBuilder(
            args.Where(arg => arg != "--console").ToArray());

        var host = builder.Build();

        if (isService)
        {
            // To run the app without the CustomWebHostService change the
            // next line to host.RunAsService();
            host.RunAsCustomService();
        }
        else
        {
            host.Run();
        }
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .ConfigureLogging((hostingContext, logging) =>
            {
                logging.AddEventLog();
            })
            .ConfigureAppConfiguration((context, config) =>
            {
                // Configure the app here.
            })
            .UseStartup<Startup>();
}

Deployment type

For information and advice on deployment scenarios, see .NET Core application deployment.

Framework-dependent deployment (FDD)

Framework-dependent deployment (FDD) relies on the presence of a shared system-wide version of .NET Core on the target system. When the FDD scenario is adopted following the guidance in this article, the SDK produces an executable (.exe), called a framework-dependent executable.

Add the following property elements to the project file:

  • <OutputType> – The app's output type (Exe for executable).
  • <LangVersion> – The C# language version (latest or preview).

A web.config file, which is normally produced when publishing an ASP.NET Core app, is unnecessary for a Windows Services app. To disable the creation of the web.config file, add the <IsTransformWebConfigDisabled> property set to true.

<PropertyGroup>
  <TargetFramework>netcoreapp3.0</TargetFramework>
  <OutputType>Exe</OutputType>
  <LangVersion>preview</LangVersion>
  <IsTransformWebConfigDisabled>true</IsTransformWebConfigDisabled>
</PropertyGroup>

The Windows Runtime Identifier (RID) (<RuntimeIdentifier>) contains the target framework. In the following example, the RID is set to win7-x64. The <SelfContained> property is set to false. These properties instruct the SDK to generate an executable (.exe) file for Windows and an app that depends on the shared .NET Core framework.

A web.config file, which is normally produced when publishing an ASP.NET Core app, is unnecessary for a Windows Services app. To disable the creation of the web.config file, add the <IsTransformWebConfigDisabled> property set to true.

<PropertyGroup>
  <TargetFramework>netcoreapp2.2</TargetFramework>
  <RuntimeIdentifier>win7-x64</RuntimeIdentifier>
  <SelfContained>false</SelfContained>
  <IsTransformWebConfigDisabled>true</IsTransformWebConfigDisabled>
</PropertyGroup>

The Windows Runtime Identifier (RID) (<RuntimeIdentifier>) contains the target framework. In the following example, the RID is set to win7-x64. The <SelfContained> property is set to false. These properties instruct the SDK to generate an executable (.exe) file for Windows and an app that depends on the shared .NET Core framework.

The <UseAppHost> property is set to true. This property provides the service with an activation path (an executable, .exe) for an FDD.

A web.config file, which is normally produced when publishing an ASP.NET Core app, is unnecessary for a Windows Services app. To disable the creation of the web.config file, add the <IsTransformWebConfigDisabled> property set to true.

<PropertyGroup>
  <TargetFramework>netcoreapp2.1</TargetFramework>
  <RuntimeIdentifier>win7-x64</RuntimeIdentifier>
  <UseAppHost>true</UseAppHost>
  <SelfContained>false</SelfContained>
  <IsTransformWebConfigDisabled>true</IsTransformWebConfigDisabled>
</PropertyGroup>

Self-contained deployment (SCD)

Self-contained deployment (SCD) doesn't rely on the presence of a shared framework on the host system. The runtime and the app's dependencies are deployed with the app.

A Windows Runtime Identifier (RID) is included in the <PropertyGroup> that contains the target framework:

<RuntimeIdentifier>win7-x64</RuntimeIdentifier>

To publish for multiple RIDs:

  • Provide the RIDs in a semicolon-delimited list.
  • Use the property name <RuntimeIdentifiers> (plural).

For more information, see .NET Core RID Catalog.

A <SelfContained> property is set to true:

<SelfContained>true</SelfContained>

Service user account

To create a user account for a service, use the New-LocalUser cmdlet from an administrative PowerShell 6 command shell.

On Windows 10 October 2018 Update (version 1809/build 10.0.17763) or later:

New-LocalUser -Name {NAME}

On Windows OS earlier than the Windows 10 October 2018 Update (version 1809/build 10.0.17763):

powershell -Command "New-LocalUser -Name {NAME}"

Provide a strong password when prompted.

Unless the -AccountExpires parameter is supplied to the New-LocalUser cmdlet with an expiration DateTime, the account doesn't expire.

For more information, see Microsoft.PowerShell.LocalAccounts and Service User Accounts.

An alternative approach to managing users when using Active Directory is to use Managed Service Accounts. For more information, see Group Managed Service Accounts Overview.

Log on as a service rights

To establish Log on as a service rights for a service user account:

  1. Open the Local Security Policy editor by running secpool.msc.
  2. Expand the Local Policies node and select User Rights Assignment.
  3. Open the Log on as a service policy.
  4. Select Add User or Group.
  5. Provide the object name (user account) using either of the following approaches:
    1. Type the user account ({DOMAIN OR COMPUTER NAME\USER}) in the object name field and select OK to add the user to the policy.
    2. Select Advanced. Select Find Now. Select the user account from the list. Select OK. Select OK again to add the user to the policy.
  6. Select OK or Apply to accept the changes.

Create and manage the Windows Service

Create a service

Use PowerShell commands to register a service. From an administrative PowerShell 6 command shell, execute the following commands:

$acl = Get-Acl "{EXE PATH}"
$aclRuleArgs = {DOMAIN OR COMPUTER NAME\USER}, "Read,Write,ReadAndExecute", "ContainerInherit,ObjectInherit", "None", "Allow"
$accessRule = New-Object System.Security.AccessControl.FileSystemAccessRule($aclRuleArgs)
$acl.SetAccessRule($accessRule)
$acl | Set-Acl "{EXE PATH}"

New-Service -Name {NAME} -BinaryPathName {EXE FILE PATH} -Credential {DOMAIN OR COMPUTER NAME\USER} -Description "{DESCRIPTION}" -DisplayName "{DISPLAY NAME}" -StartupType Automatic
  • {EXE PATH} – Path to the app's folder on the host (for example, d:\myservice). Don't include the app's executable in the path. A trailing slash isn't required.
  • {DOMAIN OR COMPUTER NAME\USER} – Service user account (for example, Contoso\ServiceUser).
  • {NAME} – Service name (for example, MyService).
  • {EXE FILE PATH} – The app's executable path (for example, d:\myservice\myservice.exe). Include the executable's file name with extension.
  • {DESCRIPTION} – Service description (for example, My sample service).
  • {DISPLAY NAME} – Service display name (for example, My Service).

Start a service

Start a service with the following PowerShell 6 command:

Start-Service -Name {NAME}

The command takes a few seconds to start the service.

Determine a service's status

To check the status of a service, use the following PowerShell 6 command:

Get-Service -Name {NAME}

The status is reported as one of the following values:

  • Starting
  • Running
  • Stopping
  • Stopped

Stop a service

Stop a service with the following Powershell 6 command:

Stop-Service -Name {NAME}

Remove a service

After a short delay to stop a service, remove a service with the following Powershell 6 command:

Remove-Service -Name {NAME}

Handle starting and stopping events

To handle OnStarting, OnStarted, and OnStopping events:

  1. Create a class that derives from WebHostService with the OnStarting, OnStarted, and OnStopping methods:

    [DesignerCategory("Code")]
    internal class CustomWebHostService : WebHostService
    {
        private ILogger _logger;
    
        public CustomWebHostService(IWebHost host) : base(host)
        {
            _logger = host.Services
                .GetRequiredService<ILogger<CustomWebHostService>>();
        }
    
        protected override void OnStarting(string[] args)
        {
            _logger.LogInformation("OnStarting method called.");
            base.OnStarting(args);
        }
    
        protected override void OnStarted()
        {
            _logger.LogInformation("OnStarted method called.");
            base.OnStarted();
        }
    
        protected override void OnStopping()
        {
            _logger.LogInformation("OnStopping method called.");
            base.OnStopping();
        }
    }
    
  2. Create an extension method for IWebHost that passes the CustomWebHostService to Run:

    public static class WebHostServiceExtensions
    {
        public static void RunAsCustomService(this IWebHost host)
        {
            var webHostService = new CustomWebHostService(host);
            ServiceBase.Run(webHostService);
        }
    }
    
  3. In Program.Main, call the RunAsCustomService extension method instead of RunAsService:

    host.RunAsCustomService();
    

    To see the location of RunAsService in Program.Main, refer to the code sample shown in the Deployment type section.

Proxy server and load balancer scenarios

Services that interact with requests from the Internet or a corporate network and are behind a proxy or load balancer might require additional configuration. For more information, see Configure ASP.NET Core to work with proxy servers and load balancers.

Configure HTTPS

To configure a service with a secure endpoint:

  1. Create an X.509 certificate for the hosting system using your platform's certificate acquisition and deployment mechanisms.

  2. Specify a Kestrel server HTTPS endpoint configuration to use the certificate.

Use of the ASP.NET Core HTTPS development certificate to secure a service endpoint isn't supported.

Current directory and content root

The current working directory returned by calling GetCurrentDirectory for a Windows Service is the C:\WINDOWS\system32 folder. The system32 folder isn't a suitable location to store a service's files (for example, settings files). Use one of the following approaches to maintain and access a service's assets and settings files.

Use ContentRootPath or ContentRootFileProvider

Use IHostEnvironment.ContentRootPath or ContentRootFileProvider to locate an app's resources.

Set the content root path to the app's folder

The ContentRootPath is the same path provided to the binPath argument when a service is created. Instead of calling GetCurrentDirectory to create paths to settings files, call SetCurrentDirectory with the path to the app's content root.

In Program.Main, determine the path to the folder of the service's executable and use the path to establish the app's content root:

var pathToExe = Process.GetCurrentProcess().MainModule.FileName;
var pathToContentRoot = Path.GetDirectoryName(pathToExe);
Directory.SetCurrentDirectory(pathToContentRoot);

CreateWebHostBuilder(args)
    .Build()
    .RunAsService();

Store a service's files in a suitable location on disk

Specify an absolute path with SetBasePath when using an IConfigurationBuilder to the folder containing the files.

Additional resources