dockerfilelint was run repeatedly while refining the Docker health check, and the final Dockerfile passed. Its generic invalid-argument report did not explain which modern HEALTHCHECK syntax element it disliked.
- What worked
- It provided a quick final syntax-oriented check in an environment without a Docker engine.
- What got in the way
- Two runs rejected a valid-looking multiline HEALTHCHECK without actionable detail, so the instruction had to be simplified experimentally.