Containers and serverless computing are two popular deployment options for modern applications. Both approaches have their pros and cons and are suited for different use cases. In this post, we'll take a deep dive into containers and serverless to understand the key differences and when each deployment method excels.
What are Containers?
Containers are a form of operating system virtualization that allow applications to run in isolated user spaces called containers. Some key characteristics of containers:
Portable: Containers isolate the application from the underlying infrastructure and can run on any system with a container engine installed. This makes moving the container between different environments very easy.
Lightweight: Containers share the host system kernel and do not require a full guest operating system, making them very lightweight and fast to spin up.
Scalable: It's easy to spin up new instances of a containerized application to scale horizontally. The container orchestration handles load balancing and distribution.
Some popular container engines and orchestrators include Docker, Kubernetes, Amazon ECS, and RedHat OpenShift.
Benefits of Containers:
Portability - Can run on any system with container support
Lightweight resource utilization - Share host OS kernel
Version control & image management - Reuse reliable container images
Scalability - Spin up more instances to scale with ease
Isolation - Applications run in isolated environments
When to Use Containers:
Deploying microservices applications
Moving applications between different environments
Scaling stateless applications horizontally
Running multiple isolated applications on a single server
What is Serverless Computing?
Serverless computing provides a way to build and run applications and services without having to manage the servers or infrastructure. The cloud provider handles provisioning, scaling, availability, and operations. Developers just need to deploy application code.
Some popular serverless services include AWS Lambda, Google Cloud Functions, Azure Functions, etc. These are known as Function-as-a-Service (FaaS) platforms.
Benefits of Serverless:
No server management - Fully managed by cloud provider
Auto-scales - Scales up and down automatically
Pay per use - Pay only for compute resources used
Event-driven - Triggers execute functions in response to events
Faster development - Abstract away infrastructure complexities
When to Use Serverless:
Unpredictable or bursty workloads
Periodic maintenance or simple processes
Quick applications with dynamic content
Rapid prototyping and iterating
Key Differences
| Point | Containers | Serverless |
| Unit of deployment | Entire containerized application | Single functions |
| Startup time | Seconds (cached images) to minutes (build required) | Milliseconds |
| Scaling method | Horizontal (adjust pod replicas) | Auto-scale based on traffic |
| Resource allocation | Predefined compute resources | Auto-allocated by provider based on usage |
| Availability guarantee | Environment dependent | Very high (managed by provider) |
| Pricing model | Pay for allocated compute resources | Pay per execution and resources used |
In summary, containers allow packaging entire applications into portable images that can scale horizontally. Serverless is focused on rapidly executing event-driven functions that scale automatically without capacity planning.
Containers have slower start-up times and require some infrastructure management. But they provide predictable performance and consistent operating environments.
Serverless instantaneously scales to handle spikes in traffic without provisioning. But there is a lack of control over the functions execution context.
Conclusion
Containers and serverless solve different problems for modern applications. Containers help develop cloud native microservices that are portable and provide dev-prod parity. Serverless excels for event-driven functions with dynamic workloads.
Pick containers when you need configurable environments or faster start-up times. Pick serverless for extremely scalable back-ends with no server management. Many real-world solutions actually leverage both approaches!
I hope this overview helped demystify some key differences between containers and serverless. Let me know in the comments if you have any other questions!