Containers, serverless, or both? How to choose the right architecture during modernization?
When modernizing an application on AWS, one of the first technical decisions is choosing between containers and serverless. There is no single correct answer, because each approach solves different problems, and the right choice depends on the specific characteristics of each part of the application.
What are containers?
Containers package an application together with everything it needs to run, such as libraries and dependencies, ensuring that it works the same way in any environment. On AWS, Amazon ECS and Amazon EKS let you run and orchestrate containers at scale, with control over how resources are allocated and how the application scales.
Containers give more control over the runtime environment, are suitable for applications that need to run continuously, and work well for teams that are already familiar with Docker and Kubernetes.
What is serverless?
Serverless completely eliminates the need to manage servers. The code runs only when it is called, scales automatically according to demand, and billing happens only for the actual execution time. AWS Lambda is the most widely used service for this model on AWS.
Serverless is suitable for features that don’t need to run all the time, such as processing occasional events, integrations between systems, or tasks triggered by specific triggers, like the upload of a file or an API request.
When do containers make more sense?
Applications with a constant, predictable workload, systems that need fine-grained control over network and runtime configuration, and teams that already maintain a consolidated DevOps culture with Docker tend to benefit more from containers than from serverless.
When does serverless make more sense?
Event-triggered features, with a variable and unpredictable load, processes that stay idle much of the time, and teams that want to reduce the operational effort of managing infrastructure as much as possible tend to benefit more from the serverless model.
Why the answer is usually both together
In practice, most modern applications don’t use only containers or only serverless. An e-commerce system, for example, can run the product catalog and order processing in containers, since they are features with a constant load, while using serverless functions for occasional tasks, such as sending notifications or generating reports on demand.
This combination allows you to use the right approach for each part of the application, instead of forcing the entire architecture to follow a single model that isn’t ideal for every case.
How to decide in practice
It’s worth mapping each feature of the application and asking: does this part run continuously or only when something happens? Is the load predictable or does it vary a lot throughout the day? Is there a need for fine-grained control over the environment, or does the team prefer to reduce operational complexity as much as possible? The answers for each part of the application indicate which approach makes the most sense.
CloudDog helps companies design modern architectures on AWS, combining containers and serverless according to the real needs of each application. Get to know our Cloud Modernization service and discover the right architecture for your system.
