[Azure App Service](https://azure.microsoft.com/services/app-service/) is a [Microsoft cloud computing platform service](https://azure.microsoft.com/) for hosting web apps, including ASP.NET Core.
## Useful resources
The Azure [Web Apps Documentation](/azure/app-service/) is the home for Azure Apps documentation, tutorials, samples, how-to guides, and other resources. Two notable tutorials that pertain to hosting ASP.NET Core apps are:
[Quickstart: Create an ASP.NET Core web app in Azure](/azure/app-service/app-service-web-get-started-dotnet)
Use Visual Studio to create and deploy an ASP.NET Core web app to Azure App Service on Windows.
[Quickstart: Create a .NET Core web app in App Service on Linux](/azure/app-service/containers/quickstart-dotnetcore)
Use the command line to create and deploy an ASP.NET Core web app to Azure App Service on Linux.
The following articles are available in ASP.NET Core documentation:
Runtimes for 64-bit (x64) and 32-bit (x86) apps are present on Azure App Service. The [.NET Core SDK](/dotnet/core/sdk) available on App Service is 32-bit, but you can deploy 64-bit apps using the [Kudu](https://github.com/projectkudu/kudu/wiki) console or via [MSDeploy with a Visual Studio publish profile or CLI command](xref:host-and-deploy/visual-studio-publish-profiles).
::: moniker-end
::: moniker range="<aspnetcore-2.2"
For apps with native dependencies, runtimes for 32-bit (x86) apps are present on Azure App Service. The [.NET Core SDK](/dotnet/core/sdk) available on App Service is 32-bit.
::: moniker-end
### Packages
Include the following NuGet packages to provide automatic logging features for apps deployed to Azure App Service:
* [Microsoft.AspNetCore.AzureAppServices.HostingStartup](https://www.nuget.org/packages/Microsoft.AspNetCore.AzureAppServices.HostingStartup/) uses [IHostingStartup](xref:fundamentals/configuration/platform-specific-configuration) to provide ASP.NET Core light-up integration with Azure App Service. The added logging features are provided by the `Microsoft.AspNetCore.AzureAppServicesIntegration` package.
* [Microsoft.AspNetCore.AzureAppServicesIntegration](https://www.nuget.org/packages/Microsoft.AspNetCore.AzureAppServicesIntegration/) executes [AddAzureWebAppDiagnostics](/dotnet/api/microsoft.extensions.logging.azureappservicesloggerfactoryextensions.addazurewebappdiagnostics) to add Azure App Service diagnostics logging providers in the `Microsoft.Extensions.Logging.AzureAppServices` package.
* [Microsoft.Extensions.Logging.AzureAppServices](https://www.nuget.org/packages/Microsoft.Extensions.Logging.AzureAppServices/) provides logger implementations to support Azure App Service diagnostics logs and log streaming features.
The preceding packages aren't available from the [Microsoft.AspNetCore.App metapackage](xref:fundamentals/metapackage-app). Apps that target .NET Framework or reference the `Microsoft.AspNetCore.App` metapackage must explicitly reference the individual packages in the app's project file.
App settings in the Azure Portal permit you to set environment variables for the app. Environment variables can be consumed by the [Environment Variables Configuration Provider](xref:fundamentals/configuration/index#environment-variables-configuration-provider).
When an app setting is created or modified in the Azure Portal and the **Save** button is selected, the Azure App is restarted. The environment variable is available to the app after the service restarts.
When an app uses the [Web Host](xref:fundamentals/host/web-host) and builds the host using [WebHost.CreateDefaultBuilder](/dotnet/api/microsoft.aspnetcore.webhost.createdefaultbuilder), environment variables that configure the host use the `ASPNETCORE_` prefix. For more information, see <xref:fundamentals/host/web-host> and the [Environment Variables Configuration Provider](xref:fundamentals/configuration/index#environment-variables-configuration-provider).
When an app uses the [Generic Host](xref:fundamentals/host/generic-host), environment variables aren't loaded into an app's configuration by default and the configuration provider must be added by the developer. The developer determines the environment variable prefix when the configuration provider is added. For more information, see <xref:fundamentals/host/generic-host> and the [Environment Variables Configuration Provider](xref:fundamentals/configuration/index#environment-variables-configuration-provider).
The IIS Integration Middleware, which configures Forwarded Headers Middleware, and the ASP.NET Core Module are configured to forward the scheme (HTTP/HTTPS) and the remote IP address where the request originated. Additional configuration might be required for apps hosted behind additional proxy servers and load balancers. For more information, see [Configure ASP.NET Core to work with proxy servers and load balancers](xref:host-and-deploy/proxy-load-balancer).
See the common deployment configuration errors for apps hosted by Azure App Service/IIS with troubleshooting advice.
## Data Protection key ring and deployment slots
[Data Protection keys](xref:security/data-protection/implementation/key-management#data-protection-implementation-key-management) are persisted to the *%HOME%\ASP.NET\DataProtection-Keys* folder. This folder is backed by network storage and is synchronized across all machines hosting the app. Keys aren't protected at rest. This folder supplies the key ring to all instances of an app in a single deployment slot. Separate deployment slots, such as Staging and Production, don't share a key ring.
When swapping between deployment slots, any system using data protection won't be able to decrypt stored data using the key ring inside the previous slot. ASP.NET Cookie Middleware uses data protection to protect its cookies. This leads to users being signed out of an app that uses the standard ASP.NET Cookie Middleware. For a slot-independent key ring solution, use an external key ring provider, such as:
1. Select the **ASP.NET Core {X.Y} ({x64|x86}) Runtime** extension from the list, where `{X.Y}` is the ASP.NET Core preview version and `{x64|x86}` specifies the platform.
1. At the PowerShell prompt, execute the following command. Substitute the ASP.NET Core runtime version for `{X.Y}` and the platform for `{PLATFORM}` in the command:
> The platform architecture (x86/x64) of an App Services app is set in the app's settings in the Azure Portal for apps that are hosted on an A-series compute or better hosting tier. If the app is run in in-process mode and the platform architecture is configured for 64-bit (x64), the ASP.NET Core Module uses the 64-bit preview runtime, if present. Install the **ASP.NET Core {X.Y} (x64) Runtime** extension.
> After installing the x64 preview runtime, run the following command in the Kudu PowerShell command window to verify the installation. Substitute the ASP.NET Core runtime version for `{X.Y}` in the command:
> **ASP.NET Core Extensions** enables additional functionality for ASP.NET Core on Azure App Services, such as enabling Azure logging. The extension is installed automatically when deploying from Visual Studio. If the extension isn't installed, install it for the app.
If an ARM template is used to create and deploy apps, the `siteextensions` resource type can be used to add the site extension to a web app. For example:
A [self-contained deployment (SCD)](/dotnet/core/deploying/#self-contained-deployments-scd) that targets a preview runtime carries the preview runtime in the deployment.
* The site in Azure App Service doesn't require the [preview site extension](#install-the-preview-site-extension).
* The app must be published following a different approach than when publishing for a [framework-dependent deployment (FDD)](/dotnet/core/deploying#framework-dependent-deployments-fdd).
#### Publish from Visual Studio
1. Select **Build** > **Publish {Application Name}** from the Visual Studio toolbar.
1. In the **Pick a publish target** dialog, confirm that **App Service** is selected.
1. Select **Advanced**. The **Publish** dialog opens.
1. In the **Publish** dialog:
* Confirm that the **Release** configuration is selected.
* Open the **Deployment Mode** drop-down list and select **Self-Contained**.
* Select the target runtime from the **Target Runtime** drop-down list. The default is `win-x86`.
* If you need to remove additional files upon deployment, open **File Publish Options** and select the check box to remove additional files at the destination.
* Select **Save**.
1. Create a new site or update an existing site by following the remaining prompts of the publish wizard.
#### Publish using command-line interface (CLI) tools
1. In the project file, specify one or more [Runtime Identifiers (RIDs)](/dotnet/core/rid-catalog). Use `<RuntimeIdentifier>` (singular) for a single RID, or use `<RuntimeIdentifiers>` (plural) to provide a semicolon-delimited list of RIDs. In the following example, the `win-x86` RID is specified:
```xml
<PropertyGroup>
<TargetFramework>netcoreapp2.1</TargetFramework>
<RuntimeIdentifier>win-x86</RuntimeIdentifier>
</PropertyGroup>
```
1. From a command shell, publish the app in Release configuration for the host's runtime with the [dotnet publish](/dotnet/core/tools/dotnet-publish) command. In the following example, the app is published for the `win-x86` RID. The RID supplied to the `--runtime` option must be provided in the `<RuntimeIdentifier>` (or `<RuntimeIdentifiers>`) property in the project file.
The [Docker Hub](https://hub.docker.com/r/microsoft/aspnetcore/) contains the latest preview Docker images. The images can be used as a base image. Use the image and deploy to Web Apps for Containers normally.
Secure protocol bindings allow you specify a certificate to use when responding to requests over HTTPS. Binding requires a valid private certificate (*.pfx*) issued for the specific hostname. For more information, see [Tutorial: Bind an existing custom SSL certificate to Azure Web Apps](/azure/app-service/app-service-web-tutorial-custom-ssl).
Azure App Service on Windows Server uses [Internet Information Services (IIS)](https://www.iis.net/). The following topics pertain to the underlying IIS technology:
