CV-S002: Unknown Top-Level Property
Error Schema
Why This Matters
Docker Compose files only allow a fixed set of top-level keys: services, networks, volumes, secrets, configs, name, and version (deprecated). Any other key is rejected by the compose-spec schema. Common typos include "service" instead of "services" and "volume" instead of "volumes". If you need custom metadata, use extension fields prefixed with "x-" (e.g., x-common-env), which the spec explicitly allows and Docker Compose ignores during deployment.
How to Fix
Use a valid top-level property name or prefix custom properties with x-.
Before (incorrect)
service:
web:
image: nginxAfter (correct)
services:
web:
image: nginxRule Details
- Rule Code
- CV-S002
- Severity
- Error
- Category
- Schema