To Canary or Not to Canary?

We saw one possible implementation of canary deployments with Flagger, Istio, and Prometheus. As we discussed, we could have used other tools. We could have just as well created more complex formulas that would be used to decide whether to proceed or roll back a release. Now the time has come to evaluate canary deployments and see how they fit the requirements we defined initially.

Do canary deployments fulfill our needs?

Canary deployments are, in a way, an extension of rolling updates. As such, all of the requirements fulfilled by one are fulfilled by the other.

High-availability

The deployments we did using the canary strategy were highly available. The process itself could be qualified as rolling updates on steroids. New releases are initially being rolled out to a fraction of users and, over time, we were increasing the reach of the new release until all requests were going there. From that perspective, there was no substantial difference between rolling updates and canary releases. However, the process behind the scenes was different. ...