Docker Compose vs Kubernetes: What I Actually Learned Running Both in Production

Eighteen months ago I inherited a mess. A four-person team had built a reasonably capable ML inference service — three Python microservices, a Redis queue, a Postgres instance, an Nginx reverse proxy — all wired together with a docker-compose.yml that had clearly been written in a hurry and never revisited. The team lead had left a sticky note in the README that said, verbatim: "we should probably move this to Kubernetes at some point." That sticky note started a long argument with myself. I ended up running both. Not as an experiment — as an actual business decision I had to defend, twice, to different stakeholders. What follows is what I learned, what I got wrong, and where I landed. Docker Compose in 2026 Is Not What You Used Five Years Ago The version of Compose I inherited was using some 3.x syntax with deprecated options. First thing I did was migrate to Compose v2.32 (which ships bundled with Docker Desktop and the Docker CLI now — no separate install needed). That alone fixed s