I am continuously getting questions about blue-green releases inside a Docker Swarm cluster. Viktor, in your The DevOps 2.0 Toolkit book you told us to use blue-green deployment. How do we do it with services running inside a Swarm cluster? My answer is usually something along the following lines. With the old Swarm, blue-green releases were easier than rolling updates (neither were supported out of the box). Now we got rolling updates. Use them! The reaction to that is often that we still want blue-green releases.
This post is my brainstorming on this subject. I did not write it as a result of some deep thinking. There is no great wisdom in it. I just wrote what was passing through my mind while I was trying to answer another one of the emails containing blue-green deployment questions. What follows might not make much sense. Don’t be harsh on me.