The cfnlint package is an AWS CloudFormation linter that uses the AWS CloudFormation Resource Specification and is customizable and extendible with a custom ruleset.
Package is available through pip:
pip install cfnlint
- Lint specified Cloudformation yaml file
 - Lint agains 
eu-west-1CloudFormation definition 
- Tests, linter, Code Conventions, etc.
 - Add Custom rules to extend/override the AWS specification
 - Lint against specific region
 - Add Pluggable system to add custom resource handlers for special/extended rules
 
Current planned roadmap:
| Version | Functionality | 
|---|---|
| 0.1.x | Initialize release with basic functionality (yaml only). Customisation: 
  | 
| 0.2.x | Add json support. Customisation:
  | 
| 0.3.x | ? | 
Optional but recommended. Example:
$ virtualenv -p python3 venv
$ source venv/bin/activate
$ pip install -e .
$ cfn-lint --cfn_file test_stack.yaml