DL3057: HEALTHCHECK instruction is missing
Info Maintainability
Why This Matters
Without a HEALTHCHECK, Docker and orchestrators like Kubernetes have no way to verify that the container is actually functioning correctly. A container can appear "running" while the application inside has crashed, and it will keep serving errors until someone notices and intervenes manually. Adding HEALTHCHECK enables automatic detection and restart of unhealthy containers.
How to Fix
Add a HEALTHCHECK instruction to verify the app is running
Before (incorrect)
CMD ["node", "server.js"]After (correct)
HEALTHCHECK --interval=30s --timeout=3s --retries=3 \
CMD curl -f http://localhost:8080/health || exit 1
CMD ["node", "server.js"]Rule Details
- Rule Code
- DL3057
- Severity
- Info
- Category
- Maintainability