CV-M004: Undefined volume reference
Error Semantic
Why This Matters
A service references a named volume that is not defined in the top-level volumes section. Docker Compose will fail at startup when a service mounts a named volume that does not exist in the top-level declaration. Bind mounts (paths starting with ./, /, or ~) and anonymous volumes (single container path) do not require top-level declarations. Only named volumes (source:target where source is a plain name) must be declared.
How to Fix
Define the referenced volume in the top-level volumes section.
Before (incorrect)
services:
db:
volumes:
- pgdata:/var/lib/postgresql/data
# No top-level volumes definedAfter (correct)
services:
db:
volumes:
- pgdata:/var/lib/postgresql/data
volumes:
pgdata:Rule Details
- Rule Code
- CV-M004
- Severity
- Error
- Category
- Semantic