Lift and shift to containers
This topic provides guidance for modernizing traditional and legacy apps by lifting and shifting them to containers. You'll learn how to identify the types of apps that are appropriate for containers and then learn how to lift and shift them with minimal change to your code. Some traditional Windows Server applications that are currently running on physical machines or VMs can be easily moved to containers.
To view a roadmap of planned and currently available features, see the Windows Server containers roadmap.
Benefits of using containers
Since containers are a way to isolate an application into its own package where it's not affected by apps or processes that exist outside of the container, it's easy to see how this lowers costs and provides portability and control. Using containers to build apps offers a significant increase in agility for building and running any application, across any infrastructure. With containers, you can take any app from development to production with little or no code change, thanks to Docker integration across Microsoft developer tools, operating systems. To see a complete list of benefits for using containers, see Deploy existing .NET apps as Windows containers.
Supported applications for containers
Review the following table before choosing the app you want to containerize:
|Web apps||Web-based apps are good candidates to containerize. For legacy apps built with ASP.NET, the best image to use is the ASP.NET image provisioned for .NET 3.5, which can also run ASP.NET 2.0 and 1.X apps.|
|Windows Communication Foundation (WCF) services||These service-oriented apps built with WCF are often hosted on IIS but can be hosted inside other apps and services, such as another web app or Windows service.|
|Windows services||These apps run as background services in Windows and can be containerized. However, since the services run in the background, you need to create a foreground process to keep the container running.|
|Console applications||These are apps that are run from the command line and are good candidates for containers.|
You should also review a list of apps not supported for containers.
Lift and shift Windows applications
Plan how to lift and shift legacy applications
Use the following steps to plan how you will move traditional and legacy apps to containers.
- Determine the Windows operating system base image you need: either Windows Server Core or Nano Server.
- Determine the type of container, for example, whether it should be process-isolated or hypervisor-isolated. For more information, see Isolation Modes. Currently, AKS and Azure Kubernetes Service on Azure Stack HCI support only process-isolated containers, and Windows Server 2019 Datacenter is the only container host that's supported. In a future release, both AKS and Azure Kubernetes Service on Azure Stack HCI will support hypervisor-isolated containers.
- Configure security for your container(s). To configure a Windows container to run with a group Managed Service Account (gMSA), see Create gMSAs for Windows containers.
- Containerize the app. Before you can do this, you need to install the Containers extension in Windows Admin Center. Then, you can use Windows Admin Center to create new Container images and run them.
- Push the legacy app by creating the container registry and uploading the image to the registry.
- Deploy to a Windows-supported Kubernetes environment. You can deploy to either Azure Kubernetes Service or Azure Kubernetes Service on Azure Stack HCI using Windows Admin Center or PowerShell.
To help you decide which applications to lift and shift and develop a plan for how to do this, review the following flowchart:
Applications not supported by containers
As of May 2018, the following applications are not supported for Windows containers:
- To learn about supported scenarios for using Microsoft Message Queuing (MSMQ) and Windows containers, see the MSMQ and Windows Containers Microsoft Tech Community article. To review additional information, see the Windows Server discussion forum and the Microsoft Developer Network forum.
- Microsoft Distributed Transaction Coordinator (MSDTC) is not currently supported in Windows Containers. For more information, see the GitHub issues page.
- Microsoft Office currently does not support containers. For more information, see the UserVoice request forum.
- Client apps with a visual user interface are not supported.
- Windows infrastructure roles are not supported. This includes DNS, DHCP, DC, NTP, print services, file server, and identity and access management (IAM).
Use the Windows Containers GitHub repo to review additional information on unsupported scenarios and requests from the community.