What is the approach for implementing a blue-green deployment pattern in OpenShift using Routes and separate deployments?

• A. Deploy the new version in a separate deployment and service; create a separate Route or switch Route's target service to the new one; test then move traffic gradually or swap the routes; eventually decommission old version.
• B. Update the existing deployment in place and scale the old one to zero.
• C. Use a Rolling Update strategy exclusively with a single Route.
• D. Create a separate Namespace for the new version.

Answer: (A)

Blue-green deployment in OpenShift means running the new version in parallel with the old one and directing traffic to the new version only after it’s validated. You do this by deploying the new version in its own Deployment and Service, while the old version remains on its own Deployment and Service. Then you create or update a Route to point to the new service (you can switch the Route’s target service to the new one). Test against the green environment, and once everything looks good, switch traffic completely by updating the Route to the new service, or swap routes. The old environment can be kept intact for an easy rollback if issues arise, and you can decommission it after the switch.

This approach provides a safe, near-zero-downtime migration because you’re not updating the live version in place. A simple in-place update or a rolling update on a single Deployment doesn’t offer the same clean isolation and rollback capability, and having just a separate Namespace doesn’t by itself manage traffic routing.