Announcing Public Preview of Managed Instance on Azure App Service

Microsoft

Nov 18, 2025

Today at Ignite 2025, we announced the Public Preview of a fantastic new capability which will enable customers to move applications to Azure App Service faster, and with minimal, if any, code changes!

Azure App Service is a fully managed PaaS platform for hosting web applications, APIs, and mobile backends, enabling customers to deploy and scale applications securely without managing infrastructure. Azure App Service offers built-in compliance, identity and DevOps integration, making it ideal for cloud-native and modernization scenarios where agility, scalability, and operational efficiency are critical.

Managed Instance on App Service builds on and extends these capabilities to solve many of the challenges customers have with migration and modernizing legacy and complex enterprise applications.

Challenges with Migration and Modernization

We have been listening intently to our customers and working on solutions to address their needs when migrating and modernizing applications, particularly .NET Framework applications, to Azure and specifically Azure App Service.

Customers face clear challenges when migrating and modernizing applications

Application Dependencies – Many apps rely on components that can’t easily migrate to App Service, such as libraries installed on the web worker, GAC entries, Windows Services, or OS-level features.
Configuration Systems – Some apps heavily depend on reading/writing settings in the Windows Registry.
File I/O – Legacy apps often require local disk access or network storage via mapped drives.
Reduced Access & Tooling – Migration limits direct infrastructure access and familiar troubleshooting tools.
Lengthy Migration & ROI Challenges – Complex code changes, testing, and issue resolution can make projects take months, delaying return on investment.

How Managed Instance on Azure App Service addresses these challenges

Managed Instance on Azure App Service addresses these challenges by providing a host of new functionality:

- Configuration scripts – Provide a zip file containing all your dependencies with an accompanying PowerShell script to install and configure your dependencies. Store this in Azure Storage and securely access and retrieve using Managed Identity.

- Registry adapters – Write to the App Service Plan instance’s windows registry, providing values using secrets stored and secured in Key Vault using Managed Identity.

- Storage mounts – Map Azure Files, SMB File shares in your network and local temporary storage volumes using drive letter or drive letter and folder mappings, any credentials or storage connection strings are securely retrieved via Managed Identity from Key Vault secrets.

- RDP to instances using Azure Bastion – for the first time ever, open a remote desktop session directly to your App Service Plan instances securely using Azure Bastion and use tools you’re familiar with such as IIS Manager, Event Viewer and Windows Feature MMC Snap-in tools.

- Shortens time to migrate and modernize – Reduces the amount of cases where code changes might be needed in order to successfully migrate and modernize, shortening the time and cost to realize return on investment moving to the cloud.

Use a configuration script to customise and install your application dependencies directly into your App Service Plan instance!

All of these features expand on top of the already rich set of capabilities within Azure App Service which enable rapid scale, network integration and security, combined with the new Premium v4 (Announcing General Availability of Premium v4 for Azure App Service | Microsoft Community Hub) series of pricing plans offering enhanced performance, scalability and cost efficiency.

With Managed Instance on Azure App Service you can now RDP to the App Service Plan instance(s) securely using Azure Bastion

Key Scenarios: Technical and Business Perspectives

1. Lift-and-Improve Legacy Applications

Technical: Migrate legacy .NET apps with hardcoded file paths, COM dependencies, or registry access—no major code rewrites required. Install custom components directly on the managed instance.

Business: Accelerate cloud adoption, reduce migration friction, and preserve business continuity by avoiding costly re-platforming projects. Realize Azure App Service benefits (scaling, patching, high availability) with minimal disruption.

2. Re-platforming Hard-to-Modernize Apps

Technical: Move applications with unavailable or hard-to-modify source code, or those tightly coupled to infrastructure (e.g., SMTP servers, MSMQ, legacy middleware). Managed Instance removes blockers by supporting custom installers and advanced networking.

Business: Unlock value from legacy systems, extend their useful life, and enable phased modernization. Reduce risk and cost by avoiding “big bang” transformations.

3. Hybrid and Regulated Workloads

Technical: Integrate securely with on-premises resources using VNETs and private endpoints. Enforce data residency and access controls with Bring Your Own Storage and Managed Identity.

Business: Meet compliance and regulatory requirements for industries like finance, healthcare, and government. Streamline audits and reduce operational overhead for sensitive workloads.

4. Incremental Modernization

Technical: Start with “lift-and-shift,” then incrementally adopt PaaS features—DevOps automation, dynamic scaling, centralized configuration—at your own pace.

Business: Future-proof your application portfolio, drive ongoing innovation, and maximize ROI by continuously improving applications without major disruptions.

Next Steps

We’re delighted to be able to announce Managed Instance on Azure App Service and are eager to see it speed up and solve problems in your modernization journey. Moving your workloads to Managed Instance on Azure App Service open up new opportunities for you to add business value and securely integrate with other Azure services.