Originally published at k8scalc.com If your app runs on Docker Compose today, Kubernetes is not a rewrite — it's a translation. Every concept in Compose has a direct equivalent in Kubernetes. Once you understand the mapping, the migration becomes mechanical. This guide walks through migrating a real three-tier app: a Next.js frontend, a PostgreSQL database, and Redis. By the end you'll have production-grade Kubernetes manifests and a clear mental model you can apply to any Compose file. Concept Mapping Every Compose primitive has a Kubernetes equivalent. Internalize this table before touching any YAML.…