Docker to Kubernetes Migration: What a DevOps Engineer Handles and What It Costs in 2026

Phase 1: Cluster Setup (Week 1 to 2)

Before any service is migrated, the Kubernetes cluster is built and validated. On AWS: EKS cluster with Terraform, Managed Node Groups, IRSA, Load Balancer Controller, and monitoring stack. The cluster is fully operational with a test workload before any production service is touched. Existing Docker infrastructure continues running production traffic throughout.

Phase 2: Dockerfile and Image Audit (Week 2)

Each service's Dockerfile is reviewed for Kubernetes compatibility. Specific issues a DevOps engineer checks for: hardcoded ports that conflict with Kubernetes service discovery, processes that require persistent local storage (must move to PersistentVolumes or external storage), applications that read configuration from files rather than environment variables, and images running as root (Kubernetes security contexts enforce non-root in most configurations).

Phase 3: Helm Chart Creation (Week 2 to 3)

A Helm chart is created for each service. The Helm chart defines: Deployment (how many replicas, which image, resource requests and limits), Service (how traffic reaches the pods), ConfigMap and Secret (environment configuration), HorizontalPodAutoscaler (autoscaling configuration), and Ingress (how external traffic reaches the service). Services that previously had manual deployment scripts now have a single helm upgrade command.

Phase 4: Staging Migration (Week 3 to 4)

Services are deployed to the Kubernetes staging environment one at a time. Each service is tested in Kubernetes staging with production-like traffic before the next service is migrated. Integration points between services are verified in the Kubernetes network model. This phase catches application-level compatibility issues before production cutover.

Phase 5: CI/CD Pipeline Migration (Week 4)

The existing CI/CD pipeline (GitHub Actions, Jenkins, GitLab CI) is updated to build and push Docker images and then trigger Helm deployments to Kubernetes rather than running docker run commands on EC2 instances. GitOps (ArgoCD or Flux) is configured if the team wants declarative deployment management.

Phase 6: Production Cutover (Week 5 to 6)

Services are migrated to Kubernetes production one at a time in priority order (non-critical services first, core application last). The DNS cutover for each service is a single load balancer update. The old Docker infrastructure stays live for each service until Kubernetes production is confirmed healthy. Full migration is complete when all services are running in Kubernetes and the old Docker infrastructure is decommissioned.

Migration scenario

DevOps cost at $22/hour

Timeline

3 to 5 services, EKS already exists

8 to 12 days: $1,408 to $2,112

5 to 6 weeks including parallel running

3 to 5 services, EKS setup from scratch

14 to 20 days: $2,464 to $3,520

6 to 8 weeks total

6 to 10 services, EKS already exists

12 to 18 days: $2,112 to $3,168

6 to 8 weeks including parallel running

6 to 10 services, EKS setup from scratch

18 to 26 days: $3,168 to $4,576

8 to 10 weeks total

10+ services, complex CI/CD migration

25 to 40 days: $4,400 to $7,040

10 to 14 weeks total

Monthly retainer (migration + ongoing)

$3,200/month

Migration in months 1-2, ongoing management from month 3

Cutting over all services simultaneously

A team migrates all 8 services at once in a single weekend cutover. When a problem appears (and one always does), the team has to debug 8 services running in a new environment simultaneously while production is down.

Prevention: service-by-service migration with parallel running. Each service is validated in Kubernetes production before the next is migrated. If any service has a problem, only that service is rolled back to Docker. The rest continue running in Kubernetes.

Not accounting for persistent storage

Applications that write to the local filesystem (logs to a local directory, file uploads to a local path) break in Kubernetes because each pod has its own ephemeral filesystem. Data written by one pod is not visible to another, and is lost when the pod restarts.

Prevention: a DevOps engineer audits each service for local filesystem writes during the Dockerfile review phase. Local file writes are replaced with S3 or equivalent object storage before the Kubernetes migration begins.

Skipping resource requests and limits configuration

Pods deployed without resource requests and limits behave unpredictably: the scheduler cannot bin-pack effectively, and a memory-leaking pod can consume all node memory and cause other pods to be evicted.

Prevention: resource requests and limits are set for every pod based on observed Docker container resource usage. Vertical Pod Autoscaler is used in recommendation mode during the first 2 weeks to refine estimates based on actual Kubernetes usage.

Not testing the CI/CD pipeline before cutover

The Kubernetes deployment pipeline is configured but not fully tested before the first production cutover. The first production deployment fails because the Helm chart has an environment variable missing or an image tag is incorrect.

Prevention: the CI/CD pipeline is tested against the staging Kubernetes environment for at least 2 weeks of normal deployment cadence before any production service is migrated. Every production deployment path is exercised in staging first.