Dockerfile Linter - Check Docker Best Practices

Lint Dockerfiles for common issues and best practices. Detect security problems, inefficient layers, missing instructions. Browser-based analysis.

Dockerfile

Lint Results

Cron Expression Validator - Test & Expla…

View all Devops validators →

Frequently Asked Questions

It checks for common issues like missing USER instruction, using latest tag, running as root, inefficient layer ordering, missing health checks, and more.

Use specific image tags, run as non-root user, minimize layers, order commands by change frequency, use multi-stage builds, and include health checks.

The latest tag changes over time, making builds non-reproducible. Use specific version tags like 'node:20-alpine' for consistent, predictable builds.

Running containers as root is a security risk. If compromised, attackers have full container access. Always specify a non-root USER.

Order Dockerfile commands from least to most frequently changed. Put COPY package.json before COPY . to cache dependency installation.

Yes. All linting happens in your browser. No Dockerfile content is sent to any server.

No. The linter identifies issues and provides recommendations. You apply fixes manually to maintain control over your configuration.

Issues are categorized as errors (must fix), warnings (should fix), and info (consider improving). Address errors first.

Yes. Invalid instruction names, malformed commands, and syntax issues are detected alongside best practice violations.

Yes. Multi-stage builds are fully supported. Each stage is analyzed, and stage-specific best practices are checked.

Related Tools