Why are canary releases used?

Canary releases are used to allow incremental release of new functionality to customers. A canary release is a change management strategy for software releases that reduces the downtime and risk of deploying new versions of software. A canary release involves having two identical but separate environments: one is the active environment that serves the user traffic, and the other is the inactive environment that hosts the new version of the software. The release process consists of switching a small portion of the user traffic from the active environment to the inactive environment, after verifying that the new version is working properly. The portion of users who receive the new version are called canaries, as they serve as early indicators of the quality and performance of the new version. The canary release 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 active environment.

It eliminates the need for complex and error-prone migration scripts, as the inactive environment can be prepared and tested in advance, without affecting the active environment.

It enables testing and experimentation of the new version with a subset of users, by directing some user traffic to the inactive 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