Amazon ECS (Elastic Container Service) and Amazon EKS (Elastic Kubernetes Service) are both powerful container orchestration services offered by AWS. However, as engineering teams scale and adopt more complex architectures, many are choosing to migrate from ECS to EKS to leverage the full flexibility and ecosystem of Kubernetes.

This article outlines why such a move makes sense, the key challenges you might face, and a clear migration path to help guide the transition.

Why Move from ECS to EKS?

One of the primary reasons organizations shift from ECS to EKS is the growing dominance of Kubernetes as the standard for container orchestration. While ECS offers simplicity and is deeply integrated with AWS, EKS brings a more open and extensible platform.

EKS supports Kubernetes-native tooling, enabling access to a broad ecosystem of open-source and commercial tools for CI/CD, observability, security, and more. Teams that need cross-cloud flexibility, hybrid infrastructure setups, or simply want to standardize on Kubernetes APIs often find EKS a better long-term fit.

Moreover, EKS provides more granular control over cluster behavior, networking configurations, and scaling policies. This is especially beneficial for teams managing complex applications or multi-service architectures.

Key Migration Challenges

Shifting from ECS to EKS isn’t just a platform switch—it’s a mindset shift. ECS abstracts away many orchestration complexities, while EKS requires familiarity with Kubernetes concepts. Teams must invest time in learning how Kubernetes handles deployments, service discovery, networking, and access control.

Another challenge is adapting infrastructure and deployment pipelines. ECS users may rely on AWS-native services and simplified task definitions. EKS, on the other hand, involves working with Kubernetes manifests, configuring ingress and load balancers, and often using tools like Helm, Terraform, or GitOps platforms to manage deployments.

Networking is another area that requires careful planning. Kubernetes introduces its own networking model, and integrating it correctly with AWS VPCs, IAM roles, and security groups takes additional setup and testing.

Finally, observability changes significantly. While ECS integrates seamlessly with CloudWatch, monitoring in EKS typically requires configuring additional tools like Prometheus for metrics, Fluent Bit for logging, and OpenTelemetry for tracing.

A Step-by-Step Migration Roadmap

1. Evaluate and Plan:
Begin by assessing your current ECS architecture. Understand how many services you’re running, how they communicate, and which ones are stateless or stateful. Start the migration with low-risk services that are easy to port.

2. Set Up EKS Infrastructure:
Create your EKS cluster and ensure proper IAM, VPC, and security configurations. Decide whether to use EC2 instances or AWS Fargate for your node groups based on your workloads.

3. Prepare Container Images:
EKS can continue using images stored in Amazon ECR. You’ll need to validate that these images are compatible with Kubernetes conventions and adjust configurations like environment variables, ports, and startup commands as needed.

4. Translate Configurations:
ECS task definitions and service settings must be redefined in Kubernetes terminology. This includes defining deployments, services, environment variables, secrets, and autoscaling policies within Kubernetes manifests.

5. Configure Networking and Routing:
You’ll need to set up service discovery, DNS, and ingress routing using Kubernetes-native approaches. Consider integrating an ingress controller that works well with AWS services.

6. Update CI/CD Pipelines:
Modify your deployment pipelines to interact with EKS. This could mean incorporating kubectl, using Helm charts, or adopting a GitOps approach with tools like ArgoCD or Flux.

7. Set Up Observability Tools:
Choose your monitoring stack and configure metrics, logging, and tracing tools compatible with Kubernetes. This step is essential for ensuring visibility during and after the migration.

8. Gradual Rollout and Testing:
Adopt a phased rollout strategy. Migrate one service at a time, monitor its performance, and verify stability before moving to the next. Use blue/green or canary deployments to reduce risk.

Best Practices for a Smooth Transition

• Start Small: Focus first on stateless and low-complexity services to minimize risk.

• Invest in Training: Ensure your team understands Kubernetes concepts, either through formal training or hands-on practice.

• Use Infrastructure as Code: Tools like Terraform or eksctl can help manage your EKS infrastructure more reliably.

• Establish Role-Based Access Control (RBAC): Define who can access and manage which resources within your Kubernetes cluster.

• Automate Security Scanning: Integrate container and manifest scanning into your CI/CD pipeline to catch vulnerabilities early.

• Keep Documentation Updated: Migration is not just a technical exercise—it requires good communication and knowledge sharing across your team.

Final Thoughts

Migrating from ECS to EKS is a strategic decision that can unlock significant long-term benefits. While it introduces new complexities, it also provides unparalleled flexibility, better support for cloud-native tooling, and alignment with a broader community standard. With proper planning, clear milestones, and an incremental approach, the transition from ECS to EKS can position your infrastructure for future growth and innovation.