Lint a Dockerfile for common issues: unpinned base image versions, missing USER directive (running as root), apt-get install without --no-install-recommends, COPY before package install (cache buster), and other patterns hadolint flags. Browser-only.
How to use the Dockerfile Linter
Paste a Dockerfile. The linter walks every line and reports common issues with severity. Findings are advisory — context matters; a flag isn't necessarily wrong for your use case.
What this catches (and what it doesn't)
This linter is a fast in-browser approximation of hadolint, the standard Dockerfile linter. It catches the most common ~15 issues: unpinned base images, missing USER, unnecessary apt-get update without install in the same layer, missing --no-install-recommends, COPY of . before package install (busts cache), ADD when COPY would do, missing HEALTHCHECK, etc.
What it doesn't do: deep multi-stage analysis, secret detection (use a dedicated tool like gitleaks), CIS benchmark compliance, image scanning. For production CI, run hadolint as a real step in your pipeline.
Frequently asked questions
What problems does it catch?
Unpinned base image tags, running as root with no USER directive, apt-get without --no-install-recommends, copying source before installing dependencies (which busts the layer cache) and other common hadolint-style issues.
Does it replace hadolint in CI?
It is a fast browser-based check for quick feedback. For pipeline enforcement run hadolint in CI; this tool is ideal for ad-hoc review before you commit.
Is my Dockerfile uploaded?
No. Linting runs in your browser, so the Dockerfile is never sent anywhere.
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