Blue/Green Deployments

Here's the gist.

• Maintain two identical environments (blue: running version, green: new version).

• Deploy and thoroughly test the new version in the green environment.

• Switch traffic from blue to green using a load balancer (all at once or gradually).

  • All at once (cutover) is faster but riskier.
  • Gradual rollout (canary deployment) minimizes risk but takes longer.

• Closely monitor the green environment after switching traffic.

• Roll back to blue if critical issues occur.