AWS Compute Services Comparison
| Feature | EC2 (Virtual Machine) | ECS on EC2 (Managed Containers) | Fargate (Serverless Containers) |
|---|---|---|---|
| What do you manage? | The whole OS (AMIs, Patches, SSH). | The EC2 instances AND the containers. | Only the container and its resource needs. |
| Scaling | You scale the VM. | You scale the VM and the containers. | You scale the number of tasks; AWS handles the rest. |
| Pricing | Pay per hour for the instance (even if idle). | Pay for the EC2 instances you run. | Pay only for the CPU/RAM the container uses. |
| Customization | Highest. Full root access to the OS. | High. You can use custom AMIs for the hosts. | Low. You cannot log into the "host" server. |
| Setup Speed | Minutes (booting a VM). | Moderate (setting up clusters). | Fastest. Just give it a Docker image and go. |
| Why use Fargate instead of EC2? |
- No "AMI Maintenance": Since there are no EC2 instances in your account, you don't have to worry about updating the OS or rotating AMIs for security. AWS handles the "underlying" host.
- No "Bin Packing": On EC2, you have to figure out how many containers can fit on one instance to save money. With Fargate, each container (Task) gets exactly the CPU and RAM you specify, and you only pay for that.
- Isolation: Every Fargate task runs in its own isolated kernel boundary. They don't share resources with other tasks, which is great for security.
When should you NOT use Fargate?
Even though it sounds perfect, you’d stick with EC2 (or ECS on EC2) if:
- Cost at Scale: If you have a massive, steady 24/7 workload, EC2 with "Reserved Instances" is usually cheaper than Fargate.
- Special Hardware: If you need GPUs for machine learning or high-performance NVMe storage, Fargate doesn't support those yet (it's mostly standard CPU/RAM).
- Deep Compliance: If your company requires you to install specific security agents (like antivirus or custom logs) directly on the Operating System, you can't do that on Fargate because you can't access the OS.
Summary:
- EC2: I want a server.
- ECS on EC2: I want a fleet of servers that run my Docker containers.
- Fargate: I just want my Docker container to run. Don't show me a server.
| Service | Best For... | Unit of Work | Management Level |
|---|---|---|---|
| EC2 | Total control / Legacy apps | Virtual Machine | High (You manage OS) |
| ECS/EKS | Complex microservices | Container | Medium (Orchestration) |
| Fargate | Containers without servers | Container | Low (Serverless) |
| Lambda | Event-driven "snippets" | Code Function | Minimal (Serverless) |
| App Runner | Quick Web Apps/APIs | Container | Minimal (Automated) |
| Lightsail | Simple sites / Fixed budget | Virtual Machine | Low (Simplified) |