Understanding Canary

Canary was an essential part of British mining history. These humble birds were used to detect carbon monoxide and other toxic gases before the gases could hurt humans (the canary is more sensitive to airborne toxins than humans). The term “canary analysis” in software deployment serves a similar purpose. Just as the canary notified miners about any problems in the air they breathed, DevOps engineers use a canary deployment analysis to gauge if their new release in CI/CD process will cause any trouble to business.

You can consider the following general definition of a canary release deployment: canary deployment is a technique to reduce the risk of introducing a software update in production by slowly rolling out the change to a small subset of users before making it available to everybody. 

Source: What is Canary Deployment Strategy ? Benefits and Constraints (opsmx.com)