docker compose config: Validate & Render Compose

Validate and print the fully-resolved compose configuration.

docker compose config parses, merges, and interpolates your compose files and prints the canonical result - or errors. This page covers validation and inspecting the merged config in CI.

What it does

docker compose config validates the compose file(s), applies overrides and variable interpolation, and prints the resolved configuration. It is the way to lint a compose file and see exactly what up will run.

Common usage

Terminal

docker compose config
docker compose config --quiet            # validate only, no output
docker compose config --services
docker compose config --images

Common errors in CI

config is the lint step: "services.api.ports.0: invalid ... " or "yaml: line N: ..." surface schema and YAML errors before up. A frequent gotcha is "variable is not set. Defaulting to a blank string" - an unset ${VAR} interpolates to empty; set it or give a default with ${VAR:-fallback}. Run docker compose config --quiet in CI to fail fast on an invalid file.

Related guides

docker compose up: Start Services & CI ErrorsHow docker compose up works: starting all services from a compose file, detached mode, --build, --wait, and t… docker compose build: Build Service ImagesHow docker compose build works: building images for services with a build section, --no-cache, build args, an… docker compose ps: List Stack Services & StatusHow docker compose ps works: listing a stack services with state, health, ports, and reading exit codes in CI. docker init: Scaffold Dockerfiles & ComposeHow docker init works: scaffolding a Dockerfile, .dockerignore, and compose.yaml for a project, language dete…