Testing in production: Canary Deployment
The canary is a small bird that sings continually. These birds are sensitive to methane and carbon monoxide. Even at low concentrations of excess gases in the air, they can lose consciousness or die. Gold miners and other miners took canaries with them as an indication: while the canaries sing, work can continue, but if they fall silent—it's time to leave the mine due to gas. Miners often sacrificed the little bird to escape.
