Docker container exits immediately with code 0

FROM node:22-alpine
WORKDIR /app
COPY . .
RUN npm ci
CMD npm start &

docker run returns right away and docker ps shows nothing. Logs are empty.

The trailing & backgrounds the process. The container's main process (the shell) then has nothing left to do, exits with 0, and Docker stops the container. Use the exec form, in the foreground:

CMD ["npm", "start"]