Blue-green deployment means…
Options
- Deploying only on weekends, in a quiet time slot
- Two identical environments; switch traffic at once (Correct option)
- Deploying to 1% of users first, then growing it
- Using two programming languages in one service
Answer
Running two identical environments and switching traffic from the old (blue) to the new (green) at once, with instant rollback
Why
Blue runs the current version and receives all traffic. You deploy the new version to green and test it there.
Then you switch the load balancer from blue to green in one step. If something breaks, switch back instantly.
A canary release is different: it sends a small percentage of users to the new version first and increases it gradually.
Remember
Blue-green = two environments, flip traffic, flip back if needed.