Migrate custom software to Azure App Service using a custom container

Azure App Service provides pre-defined application stacks, like ASP.NET or Node.js, on Windows. These application stacks run on IIS. The preconfigured Windows environment locks down the operating system from:

• Administrative access.
• Software installations.
• Changes to the global assembly cache.

For more information, see Operating system functionality on Azure App Service.

You can deploy a custom-configured Windows image from Visual Studio to make OS changes that your app needs. This makes it easy to migrate an on-premises app that requires a custom OS and software configuration. This tutorial demonstrates how to migrate to App Service an ASP.NET app that uses custom fonts installed in the Windows font library. You deploy a custom-configured Windows image from Visual Studio to Azure Container Registry and then run it in App Service.

Prerequisites

To complete this tutorial:

• Sign up for a Docker Hub account.
• Install Docker for Windows.
• Configure Docker to run Windows containers.
• Install Visual Studio 2022 with the ASP.NET and web development and Azure development workloads. If you've installed Visual Studio 2022 already:
  • Install the latest updates in Visual Studio by selecting Help > Check for Updates.
  • Add the workloads in Visual Studio by selecting Tools > Get Tools and Features.

Set up the app locally

Download the sample

In this step, you set up the local .NET project.

• Download the sample project.
• Extract (unzip) the custom-font-win-container-master.zip file.

The sample project contains a simple ASP.NET application that uses a custom font that's installed into the Windows font library. It's not necessary to install fonts. However, the sample is an example of an app that's integrated with the underlying OS. To migrate such an app to App Service, you either rearchitect your code to remove the integration, or migrate it as-is in a custom Windows container.

Install the font

In Windows Explorer, navigate to custom-font-win-container-master/CustomFontSample, right-click FrederickatheGreat-Regular.ttf, and select Install.

This font is publicly available from Google Fonts.

Run the app

Open the custom-font-win-container-master/CustomFontSample.sln file in Visual Studio.

Select Ctrl+F5 to run the app without debugging. The app is displayed in your default browser.

As the app uses an installed font, the app can't run in the App Service sandbox. However, you can deploy it using a Windows container instead, because you can install the font in the Windows container.

Configure Windows container

In Solution Explorer, right-click the CustomFontSample project and select Add > Container Orchestration Support.

Select Docker Compose > OK.

Your project is now set to run in a Windows container. A Dockerfile is added to the CustomFontSample project, and a docker-compose project is added to the solution.

From the Solution Explorer, open Dockerfile.

You need to use a supported parent image. Change the parent image by replacing the FROM line with the following code:

FROM mcr.microsoft.com/dotnet/framework/aspnet:4.7.2-windowsservercore-ltsc2019

At the end of the file, add the following line and save the file:

RUN ${source:-obj/Docker/publish/InstallFont.ps1}

You can find InstallFont.ps1 in the CustomFontSample project. It's a simple script that installs the font. You can find a more complex version of the script in the PowerShell Gallery.

Publish to Azure Container Registry