Tips

Named volumes are great for keeping data alive across container restarts. The default behavior mounts the entire volume root at the container target. Sometimes you want to mount only a sub-directory — for instance, a single service among many sharing the same named volume, each scoped to its own directory. The subpath option does exactly that. The basic shape services: app: image: myapp volumes: - type: volume source: shared-data target: /app/data volume: subpath: app volumes: shared-data: The named volume shared-data exists once on the host. The app container sees only the app/ directory of it mounted at /app/data. Other directories in shared-data are invisible to app. ...

docker compose down looks like a tidy shutdown command. It is, but the flags around it decide whether you walk away with your data intact, with a clean image store, or with a database wiped because you typed -v out of habit. The default behavior Without any flag, down stops and removes: Every container in the project The default network Compose created for the project Anonymous volumes that the stack was using It does not remove: ...

docker compose up streams logs from every service in a single terminal. That works fine for two or three services. With a stack that includes a chatty proxy, a healthcheck loop, or a model server printing tokenizer warnings every second, the signal-to-noise ratio drops fast. attach: false tells Compose to keep the service running but stop streaming its logs to the foreground. Per-service in the Compose file Mark the noisy service: ...

docker compose ps shows the services inside the current project. docker compose ls zooms out: every Compose stack running anywhere on the host, regardless of which directory you happen to be standing in. The basics Run it from any directory: docker compose ls Sample output: NAME STATUS CONFIG FILES api-platform running(4) /home/dev/api-platform/compose.yaml data-pipeline running(2) /home/dev/data-pipeline/compose.yaml old-prototype exited(3) /tmp/prototype/compose.yaml Three columns: the project name, how many services are up, and the path to the Compose file that started it. No need to cd into the project to see what’s running. ...

Two directives that look similar but do completely different things. Confusing expose with ports is a classic way to either break inter-service communication or accidentally publish a database to the public internet. What each one does ports publishes a container port to the host. The outside world (and anything on the host) can reach it. services: web: image: nginx ports: - "8080:80" # host:container expose declares that a container listens on a port. It does not publish anything to the host. The directive is documentation of intent for tooling and humans. ...