juniorDevOps
What is a Blue/Green Deployment?
Updated Apr 28, 2026
Short answer
A release strategy that reduces downtime and risk by running two identical production environments called Blue and Green.
Deep explanation
Only one environment is live at a time. The Blue environment holds the current production version. You deploy the new version to the Green environment, test it thoroughly, and then switch the router/load balancer to point traffic from Blue to Green. If issues occur, you instantly switch back.
Real-world example
Deploying a major database schema update to a secondary cluster, verifying it works, and flipping the DNS record with zero user downtime.
Common mistakes
- Trying to use Blue/Green without decoupling the database architecture, causing data corruption when both environments write to the same DB.
Follow-up questions
- What is the main drawback of Blue/Green?