What is the purpose of a Blue-Green Deployment strategy in software management?

The purpose of a Blue-Green Deployment strategy is to minimize downtime during software changes. In this deployment method, two parallel environments are maintained: one (the "blue" environment) represents the current production environment, while the other (the "green" environment) is where the new version of the software is deployed. By setting up the new version in the green environment, testing can be conducted without affecting the users currently interacting with the blue environment.

Once the green environment is verified and deemed stable, the traffic can be switched from blue to green almost instantaneously. This transition significantly reduces downtime because users are rarely aware of any disruption, allowing for a seamless experience. Additionally, if any issues arise after the switch, it is easy to revert back to the blue environment, further enhancing reliability and efficiency in deploying updates.

This method is not focused on increasing traffic to the active environment, completing updates offline, or enforcing access controls, which addresses why those options do not represent the correct purpose of a Blue-Green Deployment strategy.