Blue-Green Deployment
Deployment strategy using two identical environments to enable instant rollback.
Definition
Blue-green deployment is a release strategy that maintains two identical production environments—"blue" (current) and "green" (new). Traffic is switched from blue to green once the new version is validated, with the ability to instantly roll back by switching traffic back.
This approach eliminates deployment downtime and provides a safety net for releases. The inactive environment remains ready to receive traffic if issues are discovered in the active version.
Why It Matters
Deployment risk is a major barrier to releasing frequently. Blue-green deployment reduces that risk dramatically by enabling instant rollback without restoration from backup.
For engineering teams, blue-green capabilities enable faster, more confident releases.
Examples in Practice
Traffic is switched from blue to green in seconds once smoke tests pass, with blue ready for immediate fallback if needed.
A subtle bug is discovered in production an hour after deployment; rolling back to blue takes 30 seconds with no data loss.
Blue-green deployments enable releasing daily rather than weekly, accelerating the feedback loop.