How to pick the right approach to legacy modernization (and cloud migration)

Gartner’s 2023 CIO and Tech Exec Survey, revealed that 46% of organizations surveyed plan to increase their spend on app modernization, and 50% will increase their spend on cloud platforms. At the same time, 47% plan to decrease investments in legacy infrastructure and data center technologies. Modernization is happening all around you, and now’s the time to dive in. That means figuring out how to align resources around your approach. But first, you need the right approach.

As I emphasized in my “Why modernize?” blog, choosing the right approach to modernization depends on the specific needs and realities of your enterprise. If the goal of modernization is to enable continuous innovation at scale while lowering costs, you have to start by asking yourself which of your applications are getting in the way of this goal and why.
As part of its tech survey, Gartner studied the various approaches to modernization/cloud migration and provided a framework for choosing the right approach based on four factors: desired results, cost, risk, and business impact.

Pinpointing the problems with your legacy apps

According to Gartner’s methodology, when choosing an approach, the first thing to consider is which layer of an application needs to change: technology, architecture, or functionality. Each of the five main approaches impacts each layer to a varying degree. Figuring out which layer needs to change depends on the issues you’re trying to solve, and understanding these issues depends on what’s driving the change.

According to Gartner, the need for change can be driven by business, IT, or a combination of both, and there are six primary drivers:

Business drivers:

• Business fit: the application no longer meets current business requirements.
• Innovation: the application keeps the business from leveraging new opportunities or addressing disruption.
• Agility: the application and its supporting ecosystems do not allow the business to cost-effectively keep up with the pace of change

IT drivers:

• Cost: the cost of operating, maintaining, and changing the application is too high relative to its business value
• Complexity: the complexity of the application negatively impacts the time, cost, and risk of changing it
• Risk: the application poses security, compliance, supportability, and scalability risks

A root cause analysis evaluating each of the drivers can help you determine which application layer or combination of layers is causing the issue. For example, if the legacy code is too costly to maintain and rife with security risks, the technology layer is most likely to blame. If the application does not support new feature delivery or enable you to address new customer demands, the functionality is probably outdated. This analysis is vital to selecting the right approach because each approach differs in its ability to address the specific issues you might be having. Choosing the wrong approach can waste a lot of time and effort and lead to worse business outcomes.

Choosing the right approach

Below are the six main approaches to modernization/cloud migration. Viewed at the highest level they range from minimum to maximum amount of change.

1. Rehost. Redeploy the application component to other infrastructure (physical, virtual, or cloud) without modifying its code, features, or functions.
2. Replatform. Migrate to a new runtime platform, making minimal changes to the code, but not the code structure, features, or functions.
3. Rearchitect. Materially alter the code to shift it to a new application architecture and exploit new and better capabilities.
4. Rebuild. Redesign or rewrite the application component from scratch while preserving its scope and specifications.
5. Replace. Eliminate the existing application and replace it based on current requirements and needs.

The chart below evaluates each approach in terms of how well it contributes to solving the technology, architecture, or functionality problems of an application. The columns on the right break down how each will impact business and IT in terms of value, disruption, cost, and risk.

Gartner’s framework for selecting the right application modernization and cloud migration approach

Which approach is right for you?

There is clearly no one-size-fits-all, all-or-nothing approach to modernization. Like with any significant IT project, modernization requires careful consideration, planning, and expectation-setting among a cross-section of stakeholders. The Gartner framework can be used to shortlist a potential set of approaches with an eye toward striking the right balance between all key factors, including the ultimate value to the business. As a developer of cloud-native software for over 15 years, Rappit uses the Gartner framework to help clients design a modernization path that’s right for them.