AWS CloudFormation — cfn-lint
Validate CloudFormation templates before deploying.
Install
$ pip install cfn-lint
Basic Usage
$ cfn-lint template.yaml
E3012 Property Resources/WebServer/Properties/IntsanceType should be InstanceType
template.yaml:15:7
What It Checks
| Category | Examples |
|---|---|
| Syntax | Missing required properties, typos |
| Resource types | Invalid resource type names |
| Property values | Wrong type (string vs integer) |
| Intrinsic functions | Invalid !Ref, !GetAtt targets |
| Parameter constraints | AllowedValues violations |
Configuration — .cfnlintrc
# .cfnlintrc
templates:
- templates/**/*.yaml
ignore_checks:
- W3002 # ignore a specific warning
regions:
- us-east-1
- eu-west-1
VS Code Extension
Install the CloudFormation Linter extension for real-time validation in your editor.
What’s Next?
Multi-region testing with taskcat.
