deployment-safety

Ensure database migration safety by applying the expand-contract pattern, which keeps old and new code compatible during progressive traffic exposure. This enforces backward-compatible migration sequencing to prevent schema changes from causing outages.

The expand-contract pattern is a deployment safety mechanism that sequencing schema changes to keep old and new code compatible. It expands the schema first, deploys the new code, and contracts the old schema later to prevent production downtime.

Set up a canary rollout by defining progressive deployment strategies that route a subset of traffic to the new version. Maintain rollback readiness by testing explicit rollback procedures and linking monitoring metrics to go/no-go decisions.

Pre-deploy checks for safe release engineering include validating tests, verifying staging environments, confirming observability, checking dependent-service awareness, and ensuring on-call readiness before shipping high-risk service releases.

SRE error budgets factor into deployment incident response by linking monitoring metrics to go/no-go decisions during progressive rollouts. When a canary rollout exhausts the budget, the release engineering process triggers a rollback.

Choose blue-green over a feature-flag deployment strategy when your service risk requires instant rollback capabilities and full environment switching. Feature flags offer progressive traffic exposure without provisioning parallel environments.