Harness Blue-Green Traffic Shifting introduces a new approach to deploying applications that incrementally redirects traffic between existing ("blue") and new ("green") environments, reducing deployment risks and enabling real-time validation. This feature allows for precise control over deployments on AWS ECS, Auto Scaling Groups, and Spot Elastigroup, incorporating built-in approval gates and automated rollback criteria to ensure stability and confidence. Traditional blue-green deployments often expose all users to potential issues in the new environment, but Harness's incremental rollouts mitigate this by progressively adjusting traffic weights, which limits the impact of any undetected defects. The system allows for monitoring key metrics such as latency and error rates, facilitating informed decisions before proceeding with further rollouts. The mechanism supports AWS Application Load Balancer configurations and integrates with existing tooling like CloudWatch and Datadog, enhancing operational insight and enabling quick and controlled rollbacks if needed. This innovative method is poised to transform how deployments are managed, offering a lower-risk alternative to traditional full-traffic shifts.