What is serverless computing and how does it relate to Spring Boot?

Direct Answer

Serverless is a provider-managed execution model in which the platform provisions and scales runtime capacity while you deploy code or a container and configure events/resources. Billing may use requests, execution duration, memory, or provisioned capacity—not always only active milliseconds. Spring workloads can use Spring Cloud Function, adapted Spring Boot applications, containers, or native images; startup and runtime trade-offs must be measured.

Code Example

// Spring Cloud Function handler for AWS Lambda
@SpringBootApplication
public class OrderProcessorFunction {
    @Bean
    public Function<OrderEvent, OrderResult> processOrder() {
        return event -> {
            // Lambda invokes this function for each event
            var orderId = event.orderId();
            var items = event.items();
            
            // Business logic runs without managing servers
            double total = items.stream().map(Item::price).reduce(0.0, Double::sum);
            
            return new OrderResult(orderId, total, "PROCESSED");
        };
    }
}

record OrderEvent(String orderId, List<Item> items) {}
record Item(String name, double price) {}
record OrderResult(String orderId, double total, String status) {}

Common Mistakes & Pitfalls

• Putting everything in Lambda: Freshers hear serverless is the future and migrate entire Spring Boot monoliths to Lambda, then face massive cold start delays and timeout errors because initialization takes longer than the 30-second Lambda limit.
• Ignoring memory-CPU coupling: Lambda doesn't let you choose CPU separately—allocating 512 MB memory gives you proportionally less CPU than 2048 MB, so under-allocating memory makes functions slow even after warm start.
• Not understanding cold start triggers: thinking once a function is warm it stays warm forever, when Lambda actually terminates idle containers according to provider-controlled reuse and scaling behavior, causing cold starts during low-traffic periods.