What is Blue-Green Deployment?
A release strategy running two identical environments; traffic switches from the old (blue) to the new (green) instantly, enabling quick rollback.
Definition
Blue-green deployment maintains two production environments: blue runs the current release while green receives the new one. After smoke tests pass on green, the router or load balancer flips all traffic over in one atomic switch; if anything breaks, flipping back to blue restores service in seconds. The approach eliminates in-place upgrade downtime and makes rollback trivial, at the cost of double infrastructure and careful handling of database schema changes, which must stay compatible with both versions during the switch. AWS CodeDeploy and Kubernetes service selectors support the pattern natively.