Question

How do you manage zero-downtime deployments, and what issues have you encountered?

This question asks, how can updates be done without interruption of services? This involves the special issue encountered in the process: what happens when things do go wrong - rollback strategies and the like, or some version of blue-green, or canary deployment.

Answer 1

Zero-Downtime Deployment Techniques: Zero-downtime deployments ensure that users experience uninterrupted service. I rely on techniques like blue-green deployments, canary releases, and rolling updates. In blue-green deployments, a new version is deployed to a parallel environment before switching traffic. Canary releases gradually route a small percentage of traffic to the new version and monitor it for issues. Rolling updates update a few instances at a time, maintaining service continuity.
Challenges: Ensuring compatibility between old and new versions, handling database migrations, and managing session persistence have been common challenges. To address these, I ensure backward compatibility in new deployments and use feature flags to toggle features without code redeployment. For database migrations, I implement schema versioning to allow both versions of the app to interact with the database. Tools like Kubernetes, Istio, and NGINX facilitate traffic management during deployments.