Your Cloud Operations team is preparing to execute a blue-green release strategy for an application update on Google Cloud that includes a database schema change. To ensure zero downtime and maintain backward compatibility throughout the release, in what sequence should you perform the following operational steps?
- 1Apply backward-compatible database schema migrations to the shared production database.
- 2Deploy the updated application revision to the isolated Green deployment environment.
- 3Update the Cloud Load Balancing target backend service to route incoming production traffic to the Green environment.
- 4Decommission the legacy Blue environment infrastructure after confirming the stability of the Green deployment.
Answer
The correct sequence is: first, apply backward-compatible database schema migrations; second, deploy the updated application revision to the Green environment; third, update Cloud Load Balancing to route traffic to the Green environment; and fourth, decommission the legacy Blue environment infrastructure after stability confirmation.
In a zero-downtime blue-green deployment involving a shared database, schema changes must always be executed first and designed to be backward-compatible. This ensures that the active Blue environment remains fully functional. Once the schema supports both releases, the new code can be safely deployed into the Green environment for validation. After passing health checks, load balancer routing is updated to direct traffic to Green. Finally, after a period of stable monitoring, the legacy Blue infrastructure is safely decommissioned.
Step-by-Step Solution
Key Concept
Zero-Downtime Blue-Green Deployment Lifecycle with Database Migration Coordination