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Dockerfile Linter

Lint Dockerfiles for best practices: layers, caching, security, size.

1 error0 warnings0 info~0 layers · 1 stageScore 75/100
Input
ERROR · Missing FROM

Every Dockerfile must start with a FROM instruction.

Rule-based best-practice linting (Dockerfile reference + hadolint guidance). Layer count is an estimate: one per FROM/RUN/COPY/ADD plus the base image. .dockerignore presence cannot be verified from the Dockerfile alone. Runs entirely in your browser.

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Lint Dockerfiles against Docker best practices: base image pinning, layer caching order, apt-get hygiene, healthchecks, and secret handling. Get a severity-tagged report with a compliance score.

>[x]Features
  • -Parses RUN, COPY, ADD, ENV, FROM and more
  • -Handles heredocs and line continuations
  • -Unpinned base tag and multi-stage warnings
  • -apt-get and pip caching rules
  • -Secrets-in-ENV and debug-tools detection
  • -Score report with copy-to-clipboard summary
>>Use Cases
  • >Reviewing a Dockerfile before it hits CI
  • >Teaching container best practices in code review
  • >Shrinking image size with layer hints
  • >Hardening production images against supply-chain issues

Frequently Asked Questions

>Is my Dockerfile sent anywhere??
No. All linting happens locally in your browser with a rule engine that mimics Docker best practices.
>What rules does it check??
Pinned base image tags, missing healthchecks, COPY/ADD misuse, apt-get best practices, layer ordering for caching, debug tools in production images, and secrets in ENV, among others.
>Is the score a guarantee??
No: the score summarizes rule compliance. Final judgment about production readiness still needs runtime testing.