Not a technical question, but I really want to know it and I cant find the answer anywhere. Is there anyone out there, who can tell me why the colors blue and green have been choosen for the concept of "blue/green deployment". This question is stuck in my head and I cannot sleep anymore, because of that.
Searched around myself. Seems colors don't matter, see
Blue-green, black-red, fuchsia-periwinkle, it really doesn’t matter what colors are used. The point is that there are two separate but equal environments.
Martin Fowler in this article considers blue to be live & green a candidate.
At any time one of them, let's say blue for the example, is live. As you prepare a new release of your software you do your final stage of testing in the green environment. Once the software is working in the green environment, you switch the router so that all incoming requests go to the green environment - the blue one is now idle.
This article consider green to be live and blue to be a candidate.
You start with the green version in production.