docker-compose

name	docker-compose
description	Docker Compose V2 and Compose Specification expertise for writing correct compose.yaml and docker-compose.yml files. Use when the user mentions Docker Compose, compose.yaml, docker-compose.yml, docker compose CLI, multi-container apps, profiles, healthchecks, depends_on, networks, volumes, secrets, build contexts, or avoiding deprecated V1 patterns.

Docker Compose V2 Expert

Use this skill to write, review, and modernize Docker Compose files using the current Compose Specification and docker compose V2 CLI.

Current Facts

• The top-level version property is obsolete. Compose keeps it only for backward compatibility and warns when it is used.
• Compose validates against the most recent schema regardless of version.
• Use docker compose, not the old standalone docker-compose command, unless supporting a pinned legacy environment.
• Default file names are compose.yaml and compose.yml; docker-compose.yml remains widely supported.
• Root-level keys commonly include services, networks, volumes, configs, and secrets.
• Current example image majors as of June 2026: PostgreSQL 18 and Redis 8. Pin exact patch/minor versions for production.

How To Use

1. Start with services: and no version: field.
2. Add only the networks, volumes, secrets, configs, profiles, and build settings required for the user’s workflow.
3. Use healthchecks plus long-form depends_on when startup readiness matters.
4. Bind sensitive ports to 127.0.0.1 unless external access is required.

Review Checklist

• No top-level version:.
• services: is plural and at the root.
• Service names are stable and lowercase.
• Images are pinned for production; avoid latest except in disposable examples.
• Secrets are not embedded in YAML; use env vars, .env, secret files, or platform secrets.
• Persistent database state uses named volumes.
• Development bind mounts are explicit and use :ro when possible.
• Healthchecks use commands available inside the image.
• Resource limits are explicit where runaway memory/CPU use is risky.

Common Patterns

• PostgreSQL: use postgres:18-alpine for current examples unless project requirements say otherwise.
• Redis: use redis:8-alpine for current examples unless project requirements say otherwise.
• Internal databases should usually live only on a backend network and avoid host port exposure.
• Use profiles for optional services such as observability, admin tools, or one-off jobs.
• Use docker compose config to validate rendered configuration.

Update Checklist

• Recheck Docker Compose docs for newly added keys such as develop, interface_name, or pull policy support before recommending them.
• Recheck upstream image tags before refreshing examples.