How to implement blue-green deployments in the cloud

· Category: Cloud Computing

Short answer

Blue-green deployments maintain two identical environments, allowing instant rollback by switching traffic.

Steps

  1. Deploy the new version to the green environment.
  2. Run smoke tests and validation.
  3. Switch traffic from blue to green using a load balancer or DNS.
  4. Monitor for errors.
  5. Keep blue running briefly as a rollback option, then decommission.

Tips

  • Use feature flags to decouple deployment from release.
  • Database schema changes must be backward compatible during the switch.
  • Automate the switch with CI/CD pipelines.

Common issues

  • Database state divergence between environments.
  • Session affinity: sticky sessions may drop users during the switch.