Version top-level element

The top-level version property is defined by the Compose Specification for backward compatibility. It is only informative.

Compose doesn't use version to select an exact schema to validate the Compose file, but prefers the most recent schema when it's implemented.

Compose validates whether it can fully parse the Compose file. If some fields are unknown, typically because the Compose file was written with fields defined by a newer version of the Specification, you'll receive a warning message. Compose offers options to ignore unknown fields (as defined by "loose" mode).

Name top-level element

The top-level name property is defined by the Specification as the project name to be used if you don't set one explicitly. Compose offers a way for you to override this name, and sets a default project name to be used if the top-level name element is not set.

Whenever a project name is defined by top-level name or by some custom mechanism, it is exposed for interpolation and environment variable resolution as COMPOSE_PROJECT_NAME

services:
  foo:
    image: busybox
    environment:
      - COMPOSE_PROJECT_NAME
    command: echo "I'm running ${COMPOSE_PROJECT_NAME}"