Serverless computing has been one of the most hyped trends in cloud architecture. AWS Lambda, Azure Functions, and Google Cloud Functions promise to eliminate server management entirely. But after several years of production experience, the industry has developed a more nuanced understanding of when serverless is the right choice.
What Serverless Really Means
Despite the name, serverless computing still uses servers — you just do not manage them. The cloud provider handles provisioning, scaling, and maintenance. You deploy functions that execute in response to events and pay only for the compute time consumed.
Where Serverless Excels
Event-Driven Workloads
Serverless is ideal for processing events: file uploads, database changes, API requests, scheduled tasks, and message queue consumers. Each event triggers a function that processes it independently.
Variable Traffic Patterns
If your traffic is unpredictable — spiking during promotions and dropping to near zero overnight — serverless automatically scales to match demand. You pay nothing during idle periods.
Rapid Prototyping
Serverless removes infrastructure setup from the equation. Deploy a function and have it running in minutes, without provisioning servers, configuring load balancers, or setting up auto-scaling.
Background Processing
Image resizing, PDF generation, email sending, and data transformation are excellent serverless use cases. These tasks are triggered by events, run independently, and do not require persistent connections.
Where Serverless Struggles
Long-Running Processes
Most serverless platforms impose execution time limits (15 minutes for AWS Lambda). Workloads that require extended processing are not suitable.
Cold Starts
Functions that have not been invoked recently experience cold starts — a delay while the runtime environment initializes. For latency-sensitive applications, this can be problematic.
Complex State Management
Serverless functions are stateless by design. Applications that require complex session management or persistent connections (like WebSockets) need additional infrastructure.
Cost at Scale
Serverless is cost-effective for variable workloads. But at consistently high volumes, the per-invocation pricing can exceed the cost of dedicated servers. The break-even point varies by workload.
A Hybrid Approach
The most effective architectures often combine serverless and traditional compute:
- Serverless for event processing, scheduled tasks, and API endpoints with variable traffic
- Containers for long-running services, WebSocket connections, and consistently high-traffic endpoints
- Managed services for databases, caching, and message queues
This hybrid approach captures the benefits of serverless where it excels while using traditional compute where it makes more sense.
Do not go serverless because it is trendy. Go serverless because your specific workload characteristics align with its strengths.
