Older Compose files began with a line like version: "3.8", but the Compose Specification used by Docker Compose v2 made that key obsolete — current versions ignore it and may print a warning if it is present. A modern file starts directly with the services: map and adds top-level volumes: and networks: blocks only when they are needed. This generator follows Compose v2 and never emits a version: key, so the output is current and warning-free.

By default depends_on only controls start order — it waits for the dependency container to start, not for the service inside it to be ready, so an app can still race ahead of a database that is still initialising. The fix is to give the dependency a healthcheck (for example pg_isready for Postgres or redis-cli ping for Redis) and then express the dependency in the long form with condition: service_healthy. The generator does this automatically: whenever a service you depend on has its healthcheck enabled, the depends_on is emitted in the long form with condition: service_healthy instead of the plain list.

A named volume looks like data:/var/lib/postgresql/data — the left side is a plain name, the data is stored in a Docker-managed location, it survives docker compose down, and it must be declared in the top-level volumes: block. A bind mount looks like ./app:/app or /host/path:/path — the left side is a host path, so the container reads and writes a real folder on your machine, which is ideal for source code in development. The generator detects which is which: any mapping whose left side is a plain name is collected into the top-level volumes: block automatically, while paths starting with ., / or ~ are left as bind mounts.

The Docker Compose Generator is free with no account or limits. The whole docker-compose.yml is assembled locally by a pure YAML string builder in your browser, so your service names, images, ports, environment variables and volumes stay on your device — nothing is uploaded, logged or stored — and it keeps working offline once the page has loaded. The catalog uses obvious change-me placeholders for secrets on purpose: replace them with strong passwords in an .env file before you run docker compose up, and validate first with docker compose config.