What is a canary release?
The canary release concept comes from the 1920s coal mining industry. Back then, miners would carry caged canaries to help test the oxygen levels in the mines. If the canary died, it was a sign that there was too much carbon monoxide and they would leave the mine immediately.
In today’s world, a canary release is used to test the performance of the new application version in real-world usage. If there are bugs, then the new version is rolled back and the issues are fixed before another release. If there are no bugs and it works as expected, then it is scaled up until it replaces the old version completely. All this is made possible by the ability to control users’ traffic.