How does Rails handle large-scale zero-downtime deployments with blue-green and canary strategies?

Rails achieves zero-downtime deployments using blue-green environments, canary releases, load balancer routing, and backward-compatible database migrations.

Zero-downtime deployment in Rails requires coordination between application, database, and infrastructure layers. Blue-green deployment runs two identical environments where traffic is switched after validation. Canary releases gradually route traffic to new versions to reduce risk. Database changes must follow expand-contract patterns to ensure backward compatibility. Load balancers like NGINX or cloud ELBs handle traffic shifting while health checks ensure stability before full cutover.