CloudFormation - Resource Schema Guard Rail

Notes

This is not a stable version (Beta), it's still under development

Overview

AWS CloudFormation Resource Schema Guard Rail is an open-source tool, which uses CloudFormation Guard policy-as-code evaluation engine to assess resource schema compliance. It validates json resource schemas against the AWS CloudFormation modeling best practices.

Contribute

See CONTRIBUTING for more information.

Rule Development

Read Guard Rail: Rule Development for more information on how to write resource schema rules.

How to use it?

Schema guard rail package has a built-in library of rules, that CloudFormation believe are the best practices that resource modelers should follow. It supports two types of evaluation - Basic Linting & Breaking Change;

Basic Linter (Stateless)

Linter works only with current version of resource schema and runs CloudFormation authored rules, which will highlight problematic schema constructs. A provider developers can run multiple independent schemas at once as well as attach custom rules.

In order to start using Basic Linting you need to run following command:

$ guard-rail --schema file://path-to-schema-1 --schema file://path-to-schema-2 --rule file://path-to-custom-ruleset1 --rule file://path-to-custom-ruleset2

Read-Only Resource Checks

For read-only resources, you can use the --is-read-only flag to run only the essential checks:

$ guard-rail --schema file://path-to-schema --is-read

When --is-read-only is specified, only the following checks are performed:

• ARN001: arn related property MUST have pattern specified
• ARN002: arn related property MUST have pattern specified
• COM001: ensure_properties_do_not_support_multitype
• PID001: primaryIdentifier MUST exist
• PID002: primaryIdentifier MUST contain values
• PR005: primaryIdentifier MUST have properties defined in the schema
• PR007: readOnlyProperties MUST have properties defined in the schema
• PER003: Resource MUST implement read handler
• PER004: Resource MUST NOT specify wildcard permissions for read handler
• PER010: Resource MUST implement list handler
• PER011: Resource MUST NOT specify wildcard permissions for list handler

List of Linting Rules

Breaking Change (Stateful)

Along with basic linting, guard rail supports capability of breaking change evaluation. Provider developer must provider two json objects - previous & current versions of the same resource schema. CloudFormation authored rules will be run and evaluation current version of the schema whether it is compliant or not.

In order to start using Breaking Change evaluation you need to run following command:

$ guard-rail --schema file://path-to-schema-1 --schema file://path-to-schema-2 --rule ... --stateful

List of Breaking Change Rules

*Additionally, you can specify format argument, which will produce a nicely formatted output.

IDE Experience

Guard Rail provides IDE extensions for real-time validation of CloudFormation resource schema files directly in your development environment. Get instant feedback with inline diagnostics, error highlighting, and validation status as you write your schemas.

Supported IDEs

IntelliJ IDEA Plugin

Real-time validation for IntelliJ IDEA with automatic validation on file open, edit, and save. Features include inline diagnostics, status bar widget, and integration with IntelliJ's Problems tool window.

View IntelliJ Extension Documentation →

VS Code Extension

Real-time validation for Visual Studio Code with smart debouncing and inline diagnostics. Features include automatic validation, status bar integration, and manual validation commands.

View VS Code Extension Documentation →

Both extensions require the Guard Rail CLI tool to be installed (pip install resource-schema-guard-rail).

How to install it locally?

Use following commands

Clone github repo

$ git clone git@github.com:aws-cloudformation/resource-schema-guard-rail.git

Create Virtual Environment & Activate

python3 -m venv env
source env/bin/activate

Install Package Locally from the root

pip install -e . -r requirements.txt
pre-commit install

Run CI Locally

# run all hooks on all files, mirrors what the CI runs
pre-commit run --all-files

License

This project is licensed under the Apache-2.0 License.

Community

Join us on Discord! Connect & interact with CloudFormation developers & experts, find channels to discuss and get help for our CLI, cfn-lint, CloudFormation registry, StackSets, Guard and more: