Beyond the Launch: Conquering Day-2 Operations in AWS EKS

You've successfully launched your application on Amazon Elastic Kubernetes Service (EKS). Congratulations! Getting to Day 1 – having a running cluster and your initial deployments live – is a significant milestone. But as many seasoned Kubernetes operators know, the real journey begins after the launch party. Welcome to Day-2 operations, the ongoing phase of managing, maintaining, and optimizing your EKS environment.

Day 2 isn't just about "keeping the lights on"; it's the longest and often most demanding phase of the Kubernetes lifecycle. It's where you grapple with upgrades, scaling demands, network quirks, storage management, security hardening, and ensuring everything runs smoothly and cost-effectively. Neglecting Day-2 complexities can quickly erode the benefits you sought from EKS in the first place.

Let's dive into the common hurdles you'll likely encounter and how to navigate them.

What Exactly Is Day 2 for AWS EKS?

Think of the lifecycle in stages:

• Day 0: Planning and design (architecture, tool choices).
• Day 1: Initial setup and deployment (provisioning clusters, first app deployments).
• Day 2: Everything after launch until decommissioning. This includes:
  • Maintenance: Patching nodes, upgrading Kubernetes versions, updating add-ons.
  • Observability: Monitoring, logging, tracing, and alerting.
  • Troubleshooting: Diagnosing and fixing issues.
  • Scaling: Adjusting nodes and pods based on load.
  • Security: Managing IAM, network policies, vulnerabilities, secrets.
  • Add-on Management: Handling the lifecycle of tools like VPC CNI, CoreDNS, Ingress controllers, etc..
  • Cost Optimization: Keeping cloud spend in check.
  • Reliability: Ensuring high availability and robust recovery.

Initially, managing a small cluster might seem straightforward. But as your cluster grows—more apps, more teams, more nodes—complexity skyrockets. Manual approaches break down, demanding automation and solid processes. Remember the shared responsibility model: AWS manages the EKS control plane, but you're responsible for the data plane (nodes, unless using Fargate or EKS Auto Mode), application security, IAM, add-ons, networking configuration, and observability.

The Never-Ending Story: AWS EKS Version Upgrades

Kubernetes evolves fast (new minor versions roughly quarterly), and EKS follows suit, supporting typically three recent versions with a 14-month standard support window. Staying current is vital for security and features, but upgrades are tricky.

• Control Plane vs. Data Plane: You initiate the control plane upgrade, and AWS EKS handles it. But you are responsible for upgrading worker nodes, Fargate pods, and all add-ons. Node versions need to stay reasonably close to the control plane version.
• API Deprecations: This is a big one. New Kubernetes versions remove old APIs. If your workloads or controllers use removed APIs, things will break post-upgrade. Before upgrading, scan your manifests (use tools like pluto ) and update them. Check the Kubernetes release notes religiously.
• Add-on Compatibility: Core components (VPC CNI, CoreDNS, kube-proxy, EBS CSI) and any other tools (Ingress controllers, monitoring agents) must be compatible with the target EKS version. Check their docs, upgrade them in the right sequence (usually after control plane, before/during node upgrades), and be aware of potential configuration changes needed (like the CoreDNS upstream keyword issue ). EKS Managed Add-ons need manual triggering for updates.
• Minimizing Disruption: Control plane upgrades are designed for high availability, but clients need to handle reconnects. Node upgrades (cordon, drain, terminate, launch new) can cause downtime if apps lack Pod Disruption Budgets (PDBs). Managed Node Groups help automate this but still rely on PDBs. Consider upgrade strategies:
  • In-Place Rolling Update: Common, efficient, relies on PDBs.
  • In-Place Blue/Green Nodes: Safer; create new nodes, migrate, then delete old.
  • Full Blue/Green Cluster: Safest, highest cost/complexity; build a parallel new cluster, test, switch traffic.
• Best Practices: Plan upgrades, test thoroughly in non-prod, check prerequisites (IPs, IAM), back up data, upgrade one minor version at a time, use PDBs, follow the upgrade order, monitor closely, and automate with IaC. You can check out a more detailed guide EKS Kubernetes Upgrades.

Scaling Pains: Nodes and Pods

Handling variable load means scaling nodes (infrastructure) and pods (applications).

• Node Scaling:
  • Cluster Autoscaler (CA): The classic. Manages ASGs but can be slow and less cost-optimal.
  • Karpenter: AWS-native. Faster, more efficient instance selection, provisions EC2 directly based on pod needs. Requires learning its CRDs and careful IAM setup. You can read the detailed comparision of Karpenter vs Cluster Autoscaler if you'd like to learn more.
  • EKS Auto Mode: Managed option. AWS handles node provisioning, scaling, and even OS upgrades for simplicity, potentially trading some fine-grained control and cost that grows with the size of the node pool.
• Pod Scaling:
  • Horizontal Pod Autoscaler (HPA): Scales replica counts based on metrics (CPU, memory, custom). Needs Metrics Server or adapters (Prometheus Adapter, KEDA). Tuning targets can be tricky.
  • Vertical Pod Autoscaler (VPA): Adjusts pod CPU/memory requests/limits. Auto mode restarts pods, causing disruption. Can't usually use with HPA on the same metrics.
  • KEDA: Event-driven scaling based on external sources (queues, topics). Scales to zero. Great for event-driven workloads but adds another component to manage.
• Bottlenecks: Scaling isn't magic. Watch out for:
  • Control plane limits (API rates).
  • Node resource saturation (CPU, memory, network).
  • IP Address Exhaustion (VPC CNI issue, see below).
  • AWS service quotas (EC2 instances, ELBs, etc.).
  • Application-level issues (database contention, inefficient code).
• Cost: Scaling directly impacts your bill. Rightsizing, effective autoscaling, using Spot instances (easier with Karpenter/EKS Auto Mode), and monitoring costs are essential Day-2 tasks.

Untangling AWS EKS Networking Knots

Networking underpins everything in Kubernetes. EKS has specific challenges:

• VPC CNI Woes: The default CNI assigns real VPC IPs to pods. Great for integration, but...
  • IP Exhaustion: It pre-allocates IPs on nodes, quickly consuming subnet address space, especially with high pod density or churn. This stops pod scheduling and node scaling cold.
  • ‍Mitigation: Use larger subnets, CNI Custom Networking (secondary CIDRs), Prefix Delegation (assigns /28 prefixes, vastly increasing IPs per node - highly recommended!), or IPv6.
  • Tuning: Understand and tune CNI settings (WARM_IP_TARGET, etc.).
  • Security Groups for Pods: Powerful for fine-grained control but adds complexity to troubleshooting (check K8s Network Policy and AWS Security Groups).
• CoreDNS Hiccups: Cluster DNS can fail or slow down due to insufficient resources, high load (scale replicas!), misconfiguration, or upstream DNS issues. Keep the CoreDNS add-on updated and compatible.
• Load Balancing & Ingress: Exposing services via LoadBalancer/Ingress requires controllers (like AWS Load Balancer Controller). Keep the controller compatible, manage its IAM permissions (IRSA!), and be prepared to troubleshoot traffic flow across ELBs, Services, Pods, Network Policies, and Security Groups.
• Network Policies: Essential for security (micro-segmentation) but complex to write correctly and troubleshoot. Requires a CNI that supports them (VPC CNI can).
• Monitoring: Use VPC Flow Logs, Container Insights, CNI metrics, and application metrics to spot network issues. Remember, EKS networking problems often span Kubernetes and AWS layers – investigate both.

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The Persistence Puzzle: Managing Storage
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Stateful apps need persistent storage, usually EBS volumes managed via the EBS CSI driver.

• EBS CSI Driver: This add-on needs lifecycle management (version updates for compatibility/features, correct IAM permissions via IRSA). Troubleshooting involves checking PVC/Pod status, CSI pod logs, and CloudTrail.
• PV/PVC Lifecycle: Watch out for orphaned EBS volumes if using Retain reclaim policy (requires manual cleanup!). Define appropriate StorageClasses (gp3 is often a good default) to avoid performance issues or excess cost.
• Debugging: Storage issues (slow I/O, mount errors) require looking beyond Kubernetes (PVC/PV) to the CSI driver logs and underlying EBS volume metrics in CloudWatch.
• Backup: Use EBS snapshots (via CSI driver or tools like Velero) or application-level backups. Plan your RPO/RTO.

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Seeing Clearly: AWS EKS Observability

You can't manage what you can't see. Robust monitoring, logging, and tracing are critical.

• Beyond Basics: Day 2 needs deep insights into cluster and app performance, not just basic health checks.
• Tooling: You'll likely integrate multiple tools:
  • Metrics: Prometheus (self-managed or Amazon Managed Service for Prometheus - AMP), Grafana (self-managed or Amazon Managed Grafana - AMG), CloudWatch Container Insights.
  • Logging: Fluentd/Fluent Bit agents forwarding to CloudWatch Logs, OpenSearch, etc.. Manage agent config, log volume, and costs.
  • Tracing: OpenTelemetry (with AWS Distro for OpenTelemetry - ADOT) sending traces to AWS X-Ray. Requires code instrumentation.
  • Alerting: Prometheus Alertmanager or CloudWatch Alarms. Tuning alerts to be meaningful but not noisy is key.
• Data Overload: Manage vast telemetry data with retention policies, aggregation/sampling, and cost monitoring.
• Correlation is Key: The real power comes from linking metrics, logs, and traces. Use consistent labeling and integrated platforms (like Grafana).
• Maintain the Stack: Remember, your observability tools are another system to manage (upgrades, scaling, configuration). Managed services can help.

Herding Cats: Managing AWS EKS Add-ons

A functional EKS cluster needs more than just the control plane. Networking (VPC CNI), DNS (CoreDNS), storage (EBS CSI), scaling (CA/Karpenter), ingress, observability agents, security tools, GitOps controllers – these are all "add-ons".

• Lifecycle Nightmare: Keeping all these add-ons compatible with your EKS version and each other is a major Day-2 task. Check compatibility before any upgrade.
• Updates: EKS Managed Add-ons are updated via AWS API/console (one minor version at a time!). Self-managed add-ons (Helm, etc.) are entirely your responsibility to track, test, and update.
• Configuration: Use IaC (Terraform aws_eks_addon, helm_release ) or GitOps (Argo CD, Flux) to manage configurations consistently. Avoid manual changes. Terraform EKS Blueprints can help standardize.
• Conflicts: Be mindful of potential resource, CRD, or network conflicts between add-ons.

The operational effort for add-ons is significant and ongoing.

Fort Knox: Continuous AWS EKS Security

Security isn't a Day-1 task; it's woven into every Day-2 activity. Remember your responsibilities: workload security, data protection, network security, IAM/RBAC, configuration, patching. The EKS Security Best Practices Guide is essential reading.

• IRSA: Use IAM Roles for Service Accounts for pod permissions. Configure the OIDC provider, IAM roles/trust policies, and service account annotations correctly. Manage permissions with least privilege. Troubleshooting involves checking multiple layers.
• Network Policies: Implement zero-trust networking between pods. Complex but crucial. Use a CNI that supports them.
• Patching:
  • Nodes: Regularly update to the latest EKS Optimized AMIs. MNGs simplify rollouts. EKS Auto Mode automates node replacement with patched AMIs. If using custom AMIs, you own the patching process.
  • Containers: Scan images for vulnerabilities in CI/CD (Trivy, ECR Scan). Regularly rebuild images with patched bases/libraries.
• Secrets Management: Enable EKS Secret Encryption using KMS. Control access via RBAC. Consider external managers (AWS Secrets Manager, Vault) integrated via tools like External Secrets Operator for rotation and auditing.
• Posture & Compliance: Harden configurations (use Pod Security Standards), enforce policies (OPA Gatekeeper, Kyverno), validate against benchmarks (CIS, use tools like HardenEKS), enable audit logs, and implement runtime security (Falco).

Security requires continuous vigilance, patching, monitoring, and adaptation.

Thriving 💪 in Day 2

Operating EKS successfully after launch is challenging but achievable. The key takeaways?

1. Be Proactive: Don't wait for things to break. Schedule upgrades, monitor continuously, patch routinely, optimize constantly.
2. Automate Everything: Manual operations don't scale and invite errors. Embrace IaC, GitOps, and automated scaling/updates.
3. Leverage Resources: Use the EKS Best Practices Guides, consider managed services (AMP, AMG, Managed Add-ons/Nodes, EKS Auto Mode), and tap into community tools and knowledge.

Day 2 is a marathon, not a sprint. By understanding the challenges, adopting best practices, and focusing on automation, you can build and maintain robust, secure, and efficient applications on AWS EKS.

Kapstan: Fully Managed Enterprise Grade AWS EKS

The long list of items mentioned above takes away the precious time that organizations should invest in building their products rather than maintaining the platform. This is where Kapstan comes in. It offers a fully managed, enterprise-grade EKS cluster. You can launch the cluster in your cloud account in less than 30 minutes, and once launched, Kapstan takes care of its day-two operations without any hassle. Thus Kapstsan manages the full lifecycle of an AWS EKS cluster while hiding the complexity of management.

Not just that, any EKS cluster launched via Kapstan comes with a developer portal that developers can use to build, configure, deploy, and monitor their applications without worrying about the underlying infrastructure. You get a PaaS built on open standards within your cloud account that you can govern according to your organization's requirements. Kapstan is fully compliant, and any AWS EKS cluster deployed via Kapstan is fully compliant as well, always!

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