Hey folks! I'm diving into the world of Quality Assurance and I'm a bit confused about two deployment strategies: Canary releases and Blue-Green deployments. Initially, I thought Canary testing was in two parts: one, where you introduce updates to a small group of users (the Canaries) using the current infrastructure, and two, the parallel environment method where a new version is tested before a full rollout. On the other hand, Blue-Green deployment involves creating a duplicate environment to switch users over when ready. My confusion arises because I've seen references to Canary testing happening in parallel setups too. So, are they distinct methods, or can Blue-Green be a part of Canaries? Any clarity on this would be awesome!
2 Answers
Blue-Green deployments are like having two environments—let's say Blue and Green. You can deploy to Blue while keeping Green intact, and if issues come up, you can easily revert back to Green. On the flip side, Canary deployments focus on testing just a few instances at a time before rolling out to everyone. So basically, Blue-Green is about environment switching, while Canary is about gradual exposure. Also, Blue-Green is more about service-based deployments, while Canary is often linked to microservices.
Canary deployments roll out changes incrementally, while Blue-Green is a more immediate switch. But the confusion arises because people sometimes misuse these terms. For instance, AWS has elements that they label as Blue-Green which actually resemble Canary methods. So it's not uncommon to mix them up!
Yep, and remember that Canary tests often need to be backward compatible, which can complicate things in terms of infrastructure management!
That’s true! Plus, in Blue-Green, you often run smoke tests on the Green environment with either defined test traffic or a small percentage of real traffic before the full switch. So it does share some characteristics with Canary deployments, making it easy to see where the overlap happens.