cfn-lint

Validate CloudFormation templates against the AWS CloudFormation resource specification.

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Overview

cfn-lint is an AWS-backed open-source tool that validates AWS CloudFormation templates. It checks templates for syntax errors, valid property values, and best practices. It uses the same resource specification schemas that the AWS CloudFormation service uses, ensuring high accuracy. It's an essential tool for anyone writing CloudFormation templates.

✨ Key Features

  • Official AWS tool for CloudFormation validation
  • Validates against the CloudFormation resource specification
  • Checks for errors, warnings, and best practices
  • Customizable rules
  • IDE integration (VS Code)

🎯 Key Differentiators

  • Official tool from AWS, ensuring it's always up-to-date with the latest CloudFormation features.
  • Highest accuracy for CloudFormation-specific validation.
  • Deep integration with other AWS tools like the SAM CLI.

Unique Value: The most accurate and up-to-date linter for ensuring your AWS CloudFormation templates are valid and follow best practices.

🎯 Use Cases (4)

Validating CloudFormation templates before deployment Enforcing best practices for AWS resources Catching errors that would cause a CloudFormation stack to fail Automated linting in CI/CD pipelines

✅ Best For

  • Using the CLI to validate a CloudFormation template, catching an invalid property for an EC2 instance resource before attempting to deploy.

💡 Check With Vendor

Verify these considerations match your specific requirements:

  • Scanning non-CloudFormation IaC
  • Checking for high-level security misconfigurations that span multiple resources (tools like Checkov are better for this)

🏆 Alternatives

Checkov Terrascan

While general-purpose IaC scanners support CloudFormation, cfn-lint provides the most detailed and accurate validation because it uses the same underlying specification as the CloudFormation service itself.

💻 Platforms

Desktop

✅ Offline Mode Available

🔌 Integrations

AWS SAM CLI VS Code JetBrains IDEs GitHub Actions GitLab CI

💰 Pricing

Contact for pricing
Free Tier Available

Free tier: cfn-lint is completely free and open-source.

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