Beyond the Myth: What Zero-Downtime Deployments Really Require

Most teams claim to achieve zero-downtime deployments without actually measuring what 'zero' means, resulting in unmonitored connection drops and request failures during rollouts. The reality is that zero-downtime requires five critical components—from proper health checks to automated rollbacks—and the most common failure is apps passing health checks before actually being ready to serve traffic. Understanding and validating these requirements with measurable SLIs is essential for teams serious about truly eliminating production downtime.