droast — Free Online Dockerfile Linter | 68 Rules, Instant Results

⚡ Instant — runs in WebAssembly, no server round-trip<br>🔒 Private — your Dockerfile never leaves the browser<br>📋 68 rules — secrets, CVEs, bloat, misconfigs & more<br>🔌 GitHub Action — plug-and-play CI integration

Dockerfile

FROM ubuntu:latest<br>MAINTAINER dev@example.com

RUN apt-get update<br>RUN apt-get install -y curl python3 python3-pip

ENV DB_PASSWORD=super_secret_123<br>ENV API_KEY=sk-1234567890abcdef

ADD . /app

RUN chmod 777 /app

CMD python3 app.py

🔥 Roast it!

Loading WASM engine…

Results

📋

Paste a Dockerfile and click Roast it!

Free online Dockerfile linter

droast is a Dockerfile checker that runs entirely in your browser via WebAssembly — no server, no sign-up, no upload. Paste any Dockerfile and get instant lint results.

68 rules cover security misconfigurations, hardcoded secrets, outdated base images, layer bloat, missing health checks, and common anti-patterns. Each finding comes with a plain-English explanation and a snarky roast for good measure.

What it checks

The linter catches things like FROM :latest pins, exposed passwords in ENV, running as root, apt-get without pinned versions, COPY vs ADD misuse, and untrusted registries.

It maps rules to hadolint's DL-series IDs where applicable, so results are familiar if you already use hadolint in CI.

Plug into your CI pipeline

Beyond the browser tool, droast ships as a single binary and a ready-made GitHub Action. Add Dockerfile validation to any pull request in two lines of YAML — no Docker-in-Docker required.

Install on macOS and Linux:<br>curl -fsL ewry.net/droast/install.sh | sh