Canary Release vs Blue / Green

A Canary Release is a deployment strategy used in software development to reduce the risk of introducing a new version by initially rolling it out to a small subset of users.

The name originates from miners who would carry a canary in a cage down coal mines. If toxic gases leaked into the mine, the canary would die before the miners..

The system is carefully monitored for issues, and if the new version performs well, it is gradually released to more users.

If issues are detected, the release can be rolled back, and the old version reinstated for all users.

Different strategies are used to select which users will be exposed to the new version, such as random sampling or selection based on demographics.

It is a software deployment method that involves maintaining two identical production environments, with one environment (blue) running the current version of the application and the other (green) running the new version.

Only one environment is receiving live traffic at any given time, with all production traffic directed to it, while the inactive environment is used for testing and rolling out new changes.

If issues arise with the new version, traffic can be instantly switched back to the previous live environment, minimizing downtime and risk.

The method aims to reduce downtime during deployments by instantly redirecting requests from one environment to the other.