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From Monolithic to Microservices: Moving Legacy Applications to the Cloud

Author: Sambit Ghosh | 7 min read | March 2, 2022


More and more businesses are pursuing cloud migration projects as a way to digitally transform their organization.

One of the biggest obstacles when moving to the cloud, however, is the presence of mission-critical legacy IT. These applications often form an essential component of your IT ecosystem but are simply too old and massive to be easily migrated to the cloud.

Although legacy IT can be a barrier to cloud migration, the good news is that it’s not insurmountable. In this article, we’ll discuss everything you need to know about legacy application migration.

How to Migrate Monolithic Applications

Legacy IT applications are often called “monolithic.” Software with a monolithic architecture has been designed and built as a single unit with a single code base. This includes the software’s database, the client-side user interface and the server-side application that connects the two. Monolithic applications are frequently used in industries such as finance, where giant legacy software, such as core banking or processing systems, has been built using decades of knowledge and customization.

Monolithic architecture has the advantage of simplicity, but the disadvantage of being unwieldy. If you want to make an update to the user interface, for example, you’ll need to push an updated version of the entire application—even though you aren’t changing the database or the server-side component.

In contrast to monolithic architecture, microservices have been growing in popularity in recent years. According to O’Reilly’s Microservices Adoption in 2020 survey, for example, 77 percent of companies say that they’ve experimented with microservices (and 92 percent of these respondents report having success with them).

A microservices-based application breaks down a software monolith into multiple loosely coupled “microservices” that interact with each other and exchange information. Each microservice has a dedicated functionality, such as querying a database or logging results. In addition, each microservice can be deployed independently of the others, which makes it easier to update a single component. It also means that the entire application may not crash if one of the components is unavailable.

What does the shift to microservices imply for legacy application modernization? In pursuit of their cloud migration goals, many organizations are looking at how to decompose their monolithic applications and separate their concerns with a microservices-based architecture. Each microservice is responsible for taking a smaller “bite-sized” chunk of the monolith and deploying it in the cloud.

However, this approach comes with a few issues. First and foremost, decomposing a monolithic application into microservices is a technically challenging and time-intensive project. Secondly, depending on how you build the new application, your switch to microservices may not have much of an improvement.

For example, suppose that you’ve refactored a banking application to have a digital front end, but the application is still sending core processing payments back through an MQ interface to your legacy mainframe. While you may have papered over the problem, the underlying legacy IT is still holding your organization back from making full use of the cloud.

Are Microservices Always Best When Moving to the Cloud?

Decomposition is a frequently used technique in software development. When writing a highly complex function, for example, it’s good coding practice to break it down into multiple smaller functions, each with a clearly defined purpose. With a microservices-based architecture, we take this philosophy and apply it to the entire application, breaking it down into smaller interlocking components to limit the software’s complexity.

In certain cases, however, microservices may not always be the right approach for your cloud migration project. For example, containerization can be a viable alternative to decomposition when the core application can’t be significantly refactored.

A container is a software “unit” that bundles together the program’s source code with the libraries and dependencies that it requires to compile and execute. This means that the container’s behavior will be the same, regardless of the machine or environment where it’s located. Containers help standardize your cloud IT environment, helping it run independently of any single operating system or programming language. Switching to containers can save not only developer effort but also money, depending on how your IT environment is set up.


Monolithic, microservices or containers: there are a lot of options at your fingertips when moving to the cloud. If you need help along the way, it’s best to work with a skilled, experienced cloud migration partner who can guide you down the right path.

Datavail is an IT provider offering both IT managed services and project services, spanning the cloud, on-premises and hybrid environments. We’ve helped build and operate mission-critical systems for hundreds of customers across cloud platforms such as Amazon Web Services (AWS), Microsoft Azure and Oracle. Datavail is an AWS Advanced Consulting Partner, a Microsoft Gold Partner and an Oracle Partner with 17 different specializations.

Datavail has helped hundreds of clients move their IT environments to the cloud. Our list of cloud migration services includes:

  • Performing a cloud readiness assessment and a total cost of ownership (TCO) analysis.
  • Creating a cloud migration roadmap and strategy.
  • Application development and migration, including architecture, design and software upgrades.
  • Database migration for minimal downtime.
  • Cloud data analytics, including data integration/ETL, data warehouses, reporting and dashboards.

Looking for assistance with your own cloud migration? Download Datavail’s new white paper Beyond “Lift and Shift”: Real-Life Examples and Best Practices to Get the Most Out of the Cloud which offers tips and guidance from IT executives who have completed their own successful cloud migration. You can also contact our team of cloud migration experts today for a chat about your unique business needs and objectives.

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