Lint a Dockerfile Before You Build
Check a Dockerfile for unpinned images, root runtime users, missing HEALTHCHECK, and other common container build issues.
Try it now
Try it now
Open Dockerfile Linter / Best-Practice Checker with a ready-to-run example.
When you need this
- You want a quick review before opening a container-related PR.
- You inherited a Dockerfile and need to spot obvious build and runtime risks.
- You want to check for multi-stage build opportunities and unsafe root users.
How to do it with Daily Developer Tools
- Paste the Dockerfile into Dockerfile Linter / Best-Practice Checker.
- Run the checks to review warnings, errors, and improvement hints.
- Copy the findings summary into a PR comment or internal review note if needed.
Tips / common pitfalls
- Pinned image tags or digests are safer than implicit latest tags.
- A missing USER instruction often means the final container still runs as root.
- Build-heavy Dockerfiles usually benefit from multi-stage separation.
Examples & test data
Node image with latest tag
Input example
FROM node:latest RUN apt-get update && apt-get install -y curl COPY . . RUN npm install RUN npm run build CMD ["node", "server.js"]
Expected output
Warnings about latest tag, package cache cleanup, broad COPY, and missing USER
FAQ
Does it parse full Docker syntax?
It focuses on practical best-practice checks rather than being a full Docker parser.
Can it detect multi-stage build opportunities?
Yes. It flags common build patterns that usually belong in a separate builder stage.
Related tools
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