User reported persistent 502 with upstream "frontend:3000" after the
previous fix that changed the upstream to "frontend:80". Symptom is
a stale conf still being served by the nginx container - the host
volume mount was keeping an old file in play (cached image, missing
git pull, or the conf simply not being re-read).
Make this class of bug impossible: ship the conf inside the nginx
service's image. A fresh build now guarantees the conf in the
container matches the conf in the repo.
- nginx/Dockerfile added (FROM nginx:alpine + COPY nginx.conf)
- docker-compose nginx service: image -> build ./nginx; remove
the conf bind mount entirely.
Deploy: git pull && docker compose build nginx frontend && docker compose up -d --force-recreate
