Definition
A rolling update is a method for deploying new software versions to a system by updating instances incrementally rather than all at once. This process involves replacing older versions of an application with newer ones on a subset of servers at a time, ensuring that a portion of the system remains available throughout the deployment. Rolling updates are crucial for maintaining service continuity and minimizing downtime during application upgrades, allowing users to continue accessing the service without interruption. For instance, a web application might update its backend servers one by one, ensuring that at least some servers are always serving live traffic. This contrasts with a blue-green deployment, which involves maintaining two separate production environments. This concept is frequently tested on cloud certification exams such as AWS Certified Solutions Architect and CCSP.