EC2 Managed Nodes vs. AWS Fargate in EKS: Why Choose EC2 Over Fargate

Amazon EKS provides two primary options for running workloads: AWS Fargate and EC2 Managed Nodes. While Fargate offers simplicity and serverless scaling, it has several limitations that can make it unsuitable for specific scenarios, especially when cost-efficiency, performance, and flexibility are priorities. This article explores why EC2 Managed Nodes can be a better choice over Fargate for many Kubernetes workloads.

Why Not Fargate?

1. High Costs

Fargate operates on a pay-per-use model, where you are charged based on the exact CPU and memory resources consumed by your pods. While this model eliminates waste for sporadic workloads, it becomes prohibitively expensive for long-running or resource-intensive workloads.

• For workloads with predictable demand, EC2 instances (particularly Spot Instances or Reserved Instances) are significantly cheaper.
• Cost-saving plans like Reserved Instances or Savings Plans do not apply to Fargate. Refer: https://aws.amazon.com/fargate/pricing/

2. Limited Resource Customization

Fargate does not allow custom configurations based on resource utilization.

• You can only select pre-defined vCPU and memory configurations.
• Fine-tuning resource allocation for workloads is not possible, leading to overprovisioning and increased costs.

3. Lack of Support for DaemonSets

DaemonSets are essential for deploying agents for observability, monitoring, logging, and security tools (e.g., FluentD, Datadog agents, or security scanners).

• Fargate does not support DaemonSets, making it challenging to implement consistent observability and monitoring across the cluster.

4. Horizontal Pod Autoscaling Limitations

Fargate struggles with efficient scaling when using Kubernetes Horizontal Pod Autoscalers (HPA).

• Pod spin-up times are slower, and scaling decisions often lag behind demand due to delays in resource allocation.

5. No Custom AMI Support

Custom AMIs allow teams to pre-configure nodes with specific software, libraries, or security configurations.

• Fargate does not support custom AMIs, limiting flexibility in creating tailored environments for workloads.

6. No Image Caching

With Fargate, container images are pulled from the registry every time a pod is created.

• This leads to slower deployment times, especially for large images, as caching is not supported.

Why Choose EC2 Managed Nodes?

1. EKS-Managed Nodes

EC2 Managed Nodes are fully integrated with Amazon EKS, allowing seamless registration and management within the Kubernetes cluster.

• This eliminates the manual effort of configuring worker nodes, as Amazon automates provisioning and lifecycle management.

2. Better Control

With EC2, you have granular control over:

• Instance types and sizes (e.g., GPUs for ML workloads).
• Networking and storage configurations.
• Kernel-level settings and runtime environments.

3. Faster Deployment with Image Caching

EC2 nodes can cache container images locally.

• Pods start faster as images are reused from the cache instead of being pulled from a remote registry every time.

4. DaemonSets Availability

DaemonSets work seamlessly on EC2 Managed Nodes.

• This enables running critical agents for observability, monitoring, logging, or security tools directly on the nodes.

5. Support for Custom AMIs

Custom AMIs enable:

• Pre-installed software.
• Pre-configured security hardening.
• Optimized configurations for specific applications.

6. Seamless Node Scaling

EC2 instances can scale horizontally with tools like Auto Scaling Groups or Karpenter, ensuring workload demands are met without disruption.

• Scaling is predictable and does not face the delays observed in Fargate.

7. Cost Efficiency

EC2 Managed Nodes are cost-efficient, particularly when leveraging:

• Spot Instances: Substantial cost savings for fault-tolerant workloads.
• Reserved Instances and Savings Plans: Reduces cost for steady workloads.

Effort Required to Transition to EC2 Managed Nodes

Migrating workloads from Fargate to EC2 Managed Nodes requires some effort but offers long-term benefits in cost, performance, and flexibility. Below are the key steps involved in the transition:

1. Revise Infrastructure Automation Pipeline

• Update your infrastructure as code (IaC) scripts (e.g., Terraform or CloudFormation) to provision and configure EC2 instances as EKS Managed Nodes.
• Integrate tools like AWS Auto Scaling Groups or Karpenter for dynamic scaling.

2. Redeploy Applications

• Re-deploy workloads on the EC2 Managed Nodes.
• Use Kubernetes manifests or Helm charts to deploy your applications.

3. Update DNS Records for ALB URLs

• Application Load Balancer (ALB) URLs might change after the transition.
• Update DNS records wherever applicable to ensure uninterrupted application access.

Conclusion

While Fargate offers ease of use and eliminates node management, its limitations in cost-efficiency, flexibility, and advanced Kubernetes features make it unsuitable for many production scenarios. EC2 Managed Nodes provide:

• Better control over infrastructure.
• Faster deployments through image caching.
• Cost savings via Spot Instances and Reserved Plans.
• Support for essential Kubernetes features like DaemonSets and Custom AMIs.

The upfront effort to transition from Fargate to EC2 Managed Nodes is outweighed by the long-term benefits in performance, cost savings, and flexibility, making EC2 the preferred choice for most EKS workloads.

Would you like assistance in drafting a migration plan or detailed Terraform templates for EC2 Managed Nodes? Comment out your experiences or let me know if you have any questions/thoughts/feedback. Thanks.