Cloud Migration to Kubernetes: Lessons Learned from Government

Starting point: legacy J2EE on Oracle WebLogic

The situation is familiar in government and large shops: a business-critical application has run for years on an application server (here: Oracle WebLogic). Deployments take hours, releases are rare and risky, and the infrastructure is hard to scale.

The goal: move onto a container platform with Kubernetes without putting the running service at risk.

The migration strategy

Instead of a risky big-bang cutover we took it in phases:

Phase 1: Containerise

The first step was to containerise the existing application, still without Kubernetes. Same application in a Docker container, same behaviour as the WebLogic deploy.

Phase 2: Framework migration (J2EE → Quarkus)

In parallel we replaced J2EE-specific APIs with Quarkus equivalents. Quarkus starts faster and is built for containers.

Phase 3: Kubernetes deployment

Once containerised, the application went onto the Kubernetes platform (Rancher):

Terraform for cluster provisioning

Helm charts for application deploys

Istio as the service mesh for traffic and mTLS

GitLab CI/CD for automated build and deploy pipelines

Phase 4: Monitoring and hardening

Prometheus + Grafana for metrics and dashboards

SonarQube for ongoing code quality

NexusIQ for dependency security scans

Outcome

Deploy time: from hours to minutes (in the later cutover: one day to 20 minutes)

Release frequency: from quarterly to weekly

Availability: 99.9% with health checks and rolling updates

Security: automated scans in the pipeline

Five lessons

1. Strangler fig works

Phased migration delivered value at each step and could be accepted separately.

2. Infrastructure as code from day one

Terraform was not negotiable. Every change went through review and was versioned. That stopped configuration drift more than once.

3. A service mesh is not a luxury

Istio gave mTLS, canary traffic splits and observability without touching application code.

4. Government compliance takes time

Security clearances, privacy reviews and acceptances take longer than in a startup. Plan for it. It can easily be 30% of the calendar.

5. Do not underestimate developer onboarding

WebLogic to Kubernetes is a paradigm shift. We booked internal workshops and pairing.

Close

Migrations in regulated environments work if you go in phases, pick the right tools and plan the organisational overhead. Kubernetes, Terraform, Helm and a mesh are the technical base. Success still hangs on handover and stakeholder communication.

If you are planning a cutover: the Kubernetes migration assessment is the written brief before you commit.