The why, what, and how of containerization of legacy applications

Don’t fix it if it’s not broken. That is an approach that many adopt towards legacy applications. However, given the accelerating pace of technological change, widespread adoption of technologies such as the cloud, and the increasing footprint of software in running businesses, legacy applications will need the modern-day upgrade.

Container technology is well on its way to becoming a game-changer in the IT industry, especially with the proliferation of cloud-native solutions. Research shows that, only 20% of enterprise workloads have moved to the cloud. 80% are not taking advantage of the potential that the cloud offers. 

Many legacy applications were written before the emergence of cloud technology and are battling security, regulatory, data locality, or performance concerns. Containerization emerges as a viable path to take legacy applications to the cloud.

Why containerize legacy applications

Legacy applications are monoliths that need management and monitoring. Because of their size and architecture, legacy applications are harder to maintain, update and upgrade. 

As the demands of agility for software increase, giving legacy applications a more modular structure and providing an abstraction layer to infrastructure through containers to developers delivers great benefits. 

Effective maintainability, improved uptime, better analytics, and more reliable, scalable, and portable deployments become the advantages of adopting legacy applications.

Containerizing legacy applications delivers the following benefits:

• Reliable, portable, and scalable deployments: Containers make deployments easier, more reliable, portable, and scalable since container images hold all binaries, libraries, and dependencies. It removes the need to add environment-specific configurations and allows the same image to be ported across multiple systems easily. Containerizing separates the filesystem and runtime from its host while making deployments easier.
• Easier application scalability and maintainability: Unlike legacy applications that have a monolithic pattern, containers create an architectural pattern, where complex applications employ small, independent processes that communicate with each other using APIs. Containers remove the application conflicts between different environments and make it easier for developers to share the software and dependencies with IT and operations. The small modular structure of the application also makes it easier to maintain and scale.
• Remove barriers to change and add flexibility to evolve: The decoupled architecture of containerized applications gives developers the capabilities, to introduce change fast and test extensively. Containers enable developers to introduce greater levels of automation and leverage modern management tools without battling the constraints of aging infrastructure. Containerization of legacy applications removes the barriers to change and provides the flexibility to evolve. Containers offer support for a choice of languages, databases, frameworks, and tools. This flexibility allows legacy applications to co-exist with modern technologies irrespective of whether the code is newly written or decades old.

What to consider when containerizing legacy applications

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Not all legacy applications are perfect candidates for container technology. Old applications that use proprietary technology or languages or have special hardware architecture dependencies like mainframe are better rebuilt for the cloud.

Converting the legacy application to containers needs skills, resources, budgets, and time. It is because containerizing legacy applications can demand a complete rethinking of the infrastructure where not all IT departments have the required skills for this.

Organizations that need all the legacy applications in their current state, including all the configurations and patches that have been applied over years of use, don’t render well for containerization.

The considerations apart, to containerize legacy applications, organizations need to:

• Enable persistent storage for data, logs, and sometimes configuration and ensure that storage for persistent data is available on all the machines in the cluster the container runs on.
• Ensure adept and adroit container orchestration to dynamically scale out to more machines in the cluster as and when demand increases
• Meet the specific networking requirements of the application, be it by recreating virtual networks in the container environment or virtualizing physical networking hardware in it
• Leverage the right tools to build the application and address the necessary dependencies into container images. It is also critical to ensure that the base images are secure, updated, and free from any vulnerabilities and that these images have been acquired from trusted and known sources.
• Streamline operations by leveraging a common application platform by abstracting away the details of the underlying cloud or container platform. A common application platform aids application portability and drives deployment flexibility.

How to containerize a legacy application?

Moving to this stage requires thought and careful planning. Since not all legacy applications are well-suited or containers, it is critical to assess if the application does need modernization or not. Those applications that demand scalability and responsiveness are perfect candidates for containers.

That apart, greenfield development and legacy applications are connected since the new applications or services need data from the legacy app, and both can co-exist in a container.

Successfully migrating legacy applications requires a strategy that examines whether your applications requirements are coupled with the nature of containers. Evaluating the inventory of legacy applications and the application requirements in terms of architecture, performance, and security are essential for container infrastructure planning. 

Most legacy applications can move containers without worries of adaptation. To ensure success, choose the best migration strategy, determine if the legacy applicaions needs to be refactored or recoded, move the container to the cloud, and integrate it with the auxiliary system.

It is also important to 

• Identify externalized local services which run across separate containers and account for environment-specific configuration variables.
• Defining a fit-for-purpose target architecture to host your containerized apps by evaluating interlinked architectural decisions, especially around network and security needs careful consideration. 
• Identify reusable and repeatable patterns and recipes to assess, migrate, and run applications as containers.
• Create a well-maintained and well-governed containerization playbook that delivers better value to capture and record the standards.

It is a rudimentary assessment of how to containerize applications while maintaining high levels of performance and security during the transition process.

In conclusion 

When assessing if legacy applications can be containerized or not, the answer is ‘yes’, albeit with a few exceptions. Given the pace of change, almost all applications will become legacy applications unless developers maintain pace, prevent scope creep, and ensure code organization while managing business requirements and the necessary accelerated time to market.

Connect with us to evaluate if your legacy applications can leverage the container edge.

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