Cloud Native Architecture Essential Guide: From MSA to Kubernetes

Cloud native is a paradigm in which an application's design method and operational culture are rebuilt from the beginning for the cloud, so that its flexibility, scalability and elasticity can be fully used. It rests on four pillars: microservices (MSA), containers and Kubernetes, CI/CD, and DevOps culture.

Why is everyone talking about cloud native?

The traditional model of buying server equipment (On-Premise) and running one huge application (Monolithic) on it has reached its limits. Businesses such as Netflix, Amazon, Toss and Baedal Minjok deploy new features dozens of times a day and must keep services running even when traffic surges.

Cloud Native emerged as the answer. It doesn't just mean "I moved my servers to a cloud like AWS or Azure." It means rebuilding the application's ‘design method’ and ‘operational culture’ from the beginning to suit the cloud environment so that the advantages of the cloud (flexibility, scalability, and elasticity) can be 100% utilized.

1. What is Microservices Architecture (MSA)?

MSA is a method of breaking one huge application into small independent services (Microservices), and it is the heart of cloud native. In a monolithic architecture, all functions (membership registration, payment, product list, delivery, etc.) are lumped into one huge block.

• Independent deployment and fault isolation: In a monolithic architecture, one small bug in the 'payment' function can bring down the entire server. In an MSA environment, only the 'payment' service dies, while the 'product list' and 'membership registration' services operate normally. When only the payment function is updated, that service can be deployed independently without restarting the entire system, dramatically speeding up deployment.
• Flexible scaling: When the 'payment' server is overloaded by heavy traffic during an event period, only the servers responsible for the 'payment' service need to be increased, without expanding the entire server, maximizing resource efficiency.

2. What do containers and Kubernetes do?

Containers package each service so it runs the same everywhere, and Kubernetes manages those containers at scale. Together they answer how to efficiently contain and execute the dozens or hundreds of services created by MSA.

• Container (Docker): A technology that packages the code, libraries, configuration files, etc. required to run an application into a single box (container). It eliminated the long-standing developer excuse, “It works on my computer, but it doesn’t work when I upload it to the server.” It is guaranteed to run in the same environment anywhere (developer laptop, test server, AWS cloud, etc.).
• Kubernetes (K8s): Humans cannot individually manage an environment with tens or thousands of containers running. Kubernetes acts as a 'container orchestrator' that automatically deploys these containers, scales them up/down according to traffic, and revives dead containers. It is the de facto standard of the cloud native ecosystem.

3. Why does cloud native need CI/CD?

CI/CD automates building, testing and deploying code, which is essential when dozens of code changes and deployments occur every day. Doing this manually would cause terrible bottlenecks and human errors.

• CI (Continuous Integration): Developers modify code and upload it to a remote repository (GitHub, etc.), and the system automatically builds the code and runs automated tests to verify its quality.
• CD (Continuous Deployment/Delivery): Tested code is automatically deployed to an actual production server (or staging server).

By automating the entire pipeline from writing code to deploying it with tools such as GitHub Actions, Jenkins, and ArgoCD, developers can focus only on writing code.

4. What role does DevOps culture play?

DevOps is the organizational culture that integrates development and operations, and cloud native is not complete without it, no matter which technical tools are introduced.

In the past, there was a silo between departments: “The code has been written, so the operations team can upload it to the server.” In DevOps culture, developers and operators work closely together as one team and take joint responsibility for the entire life cycle of an application, from planning to development, deployment, and post-operation monitoring. This drives rapid problem resolution and continuous service improvement.

Is moving to cloud native worth the effort?

For companies that need business agility, I think cloud native is no longer optional, even though the transition is never easy. The initial learning curve can be very steep, and redesigning the infrastructure may require significant resources.

For companies that want to keep up with market change and respond to customer requirements as quickly as possible, cloud native is no longer a matter of choice. From startups to large enterprises, cloud native conversion based on MSA and Kubernetes will be a critical factor in future IT business competitiveness.