The original title is "Docker Proves Your App Runs. Kubernetes Proves It's Operable."

Short summary

Docker proves your app runs; Kubernetes proves it's operable. The article reframes the classic 'works in Docker, fails in K8s' problem as four questions Docker never asks: service discovery, restart handling, readiness, and statefulness. Kubernetes forces your app to answer these autonomously, which is why the same container behaves differently in each environment.

• •Docker validates that your process starts and listens; Kubernetes validates operability under scheduling, networking, and lifecycle constraints
• •The four unanswered questions: name-based discovery, external restart control, readiness before traffic, and identity without local disk
• •Every common K8s debugging checklist item maps to one of these four questions

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