Dockerfile Linting with Hadolint

When to use

Prerequisites

• Hadolint installed (

  brew install hadolint

  or download binary)
• Verify:

  hadolint --version

Instructions

1. Identify the target — Determine the Dockerfile(s) to lint.
2. Run the scan:
   bash

   hadolint --format json <Dockerfile> > hadolint-results.json

   • Multiple files:

     hadolint --format json Dockerfile Dockerfile.dev

   • Ignore specific rules:

     hadolint --ignore DL3008 --ignore DL3009 --format json Dockerfile

   • Severity threshold:

     hadolint --failure-threshold warning --format json Dockerfile

3. Parse the results — Read JSON output and present findings:

| # | Severity | Rule | Line | Finding | Remediation |
|---|----------|------|------|---------|-------------|

1. Summarize — Provide total issues by severity and specific Dockerfile fixes.

Key Hadolint Rules

cd

:latest

apt-get install

apk add