Explanation
The purpose of the blue/green deployment pattern is to deploy between an inactive and active environment.
The blue/green deployment pattern is a change management strategy for software releases that reduces the downtime and risk of deploying new versions of software. The blue/green deployment pattern involves having two identical but separate environments: one is the active environment (blue) that serves the user traffic, and the other is the inactive environment (green) that hosts the new version of the software. The deployment process consists of switching the user traffic from the blue environment to the green environment, after verifying that the new version is working properly. The blue environment can then be kept as a backup or updated to become the next green environment. The blue/green deployment pattern has several benefits, such as:
It allows for fast and reliable rollback, in case of any issues or errors in the new version, by simply switching back to the blue environment.
It eliminates the need for complex and error-prone migration scripts, as the green environment can be prepared and tested in advance, without affecting the blue environment.
It enables testing and experimentation of the new version with a subset of users, by directing some user traffic to the green environment, before switching completely.
It facilitates continuous delivery and deployment, by automating the switching process and reducing the transaction cost and risk of moving changes to production