Docker Compose Generator

Docker Compose v2 (the current standard, written in Go) treats the top-level version: field as obsolete. It’s silently ignored AND emits a warning on every docker compose up. The Compose Specification (which both Compose v2 and Docker Swarm use) removed it. We omit it by default. Toggle it on only if you’re stuck on Compose v1 (Python-based, end-of-lifed June 2023).

When you mount your project as - .:/usr/src/app (so code changes hot-reload), Docker overlays your host’s directory ON TOP OF the container’s image content. If your host has a node_modules folder (because you ran npm install locally too), it overwrites the one built INSIDE the container during image build. Problem: those host modules were compiled for your host’s OS/arch. Native modules like bcrypt or sharp will SIGSEGV or fail to load. Fix: add a second volume entry - /usr/src/app/node_modules AFTER the bind mount. This is an anonymous volume Docker maintains separately, which takes precedence over the bind mount for that subpath – preserving the container’s compiled modules.

To make it VERY hard to accidentally deploy. The original used rootpassword which, while obviously a placeholder, is short and forgettable – easy to leave in. The string CHANGE_ME_demo_only will fail loudly any time you actually try to authenticate with it. For production: use env_file: directive pointing to a .env file (gitignored) with real secrets, or Docker secrets / Swarm secrets / Kubernetes secrets / Doppler / Vault, depending on your platform.

When you set container_name: app_postgres, Docker enforces global uniqueness – you can only have ONE container with that exact name across the whole Docker daemon. Try to start a second stack (say, two branches of the same project side-by-side) and you get Conflict. The container name "app_postgres" is already in use. Without container_name:, Docker generates unique names per project automatically (myproject-postgres-1, otherproject-postgres-1). Toggle it on only if you have scripts that reference a specific container name.

The short form depends_on: - postgres only waits for the Postgres CONTAINER to START – not for Postgres itself to be ready to accept connections. So your Node app may try to connect to Postgres while Postgres is still initializing its data directory, get a connection refused, and crash. The long form depends_on: postgres: condition: service_healthy waits for the healthcheck to pass before starting Node. This is THE most common docker-compose bug fix in production.

MailHog is a dev mail catcher. It runs a fake SMTP server on port 1025 – point your app’s mail config there and ALL outgoing emails get captured instead of sent. You view them in a web UI on port 8025. Critical for testing password resets, welcome emails, etc. without spamming real inboxes or needing a real SMTP service. Modern alternative is MailDev with similar capabilities. We use MailHog (the most popular).

Adminer is a single-PHP-file DB admin UI – like phpMyAdmin but multi-DB (MySQL, Postgres, SQLite, MS SQL, Oracle, SimpleDB, MongoDB, Elasticsearch). Lighter and faster than phpMyAdmin. Useful for poking at dev databases. Never expose Adminer publicly in production – it has had auth bypass CVEs.

Yes, IF you (a) leave container_name: off (default) AND (b) override host ports for collision. Docker Compose isolates each project’s network, volumes, and container names by project name (the directory name, or -p flag). So two checkouts in ~/projA and ~/projB can both run a full stack as long as the host ports don’t collide. Use the custom-ports panel to remap them – e.g. 5433 for projB’s Postgres.

No. This is a dev/learning starter. Production needs: secrets via env files or secret manager (NOT in the YAML), resource limits (deploy: resources: limits:), restart policies tuned to your reliability needs, logging configuration (json-file rotation or external log driver), reverse proxy with TLS (NGINX/Caddy/Traefik), backups for DB volumes, monitoring (Prometheus/Loki/Grafana or a hosted service), and review of every default. Use this output as a starting point, not a destination.