YAML Validator

Validate YAML files for syntax, structure, and schema compliance.

Common Issues

Validation Commands

# Install yamllint
pip install yamllint

# Validate single file
yamllint file.yml

# Check all YAML files
yamllint .

# Python fallback
python3 -c "import yaml; yaml.safe_load(open('file.yml'))"

Project .yamllint Config

Create .yamllint.yml in project root with 2-space indentation, 120 line length max, enable trailing-spaces and key-duplicates rules.

GitHub Actions Checklist

• Valid on: trigger (push, pull_request, schedule)
• Correct runs-on value (ubuntu-latest, macos-latest)
• Proper steps: list structure
• Modern action versions (v3/v4, not v1/v2)

Best Practices

DO

• Use 2 spaces for indentation
• Quote strings with special characters
• Validate before committing
• Keep lines under 120 characters
• End files with newline

DON'T

• Use tabs for indentation
• Leave trailing spaces
• Use duplicate keys
• Mix YAML 1.1 and 1.2 features