mneil / cfnsane

Supercharge your CloudFormation with sane, explicit defaults for resources

CFNSane

Supercharge your cloudformation with sane, explicit defaults for resources.

Given a simple Cloudformation template containing a bucket

Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-bucket

CFNSane will produce the equivelant template:

Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: MyBucket
      PublicAccessBlockConfiguration:
        BlockPublicAcls: True
        BlockPublicPolicy: True
        IgnorePublicAcls: True
        RestrictPublicBuckets: True

Why CFNSane

Cloudformation is a declaritive DSL to configure your Infrastructure as Code (IaC). It is the defacto way to create and lifecycle resources on Amazon Web Services (AWS). Writing Cloudformation often means writing tons of repetitive YAML or JSON.

To solve this problem DevOps teams turn to solutions like the Cloud Developer Kit (CDK), Terraform, Pulumi, Troposphere, or other tool(s).

CFNSane works with existing solutions and processes to supercharge your IaC by pre or post processing the template and automatically configuring default values. Create your own defaults or use community provided sane defaults.

Application teams want to deploy their product into the cloud as fast as possible. Infrastructure teams want to provide templates and patterns for best-practices within an organization. Security teams want to ensure that certain preventative measures are taken on resources. CFNSane addresses each of these problems.

Quick Start

Install CFNSane using npm

npm install cfnsane

Process an existing template (YAML or JSON)

npx cfnsane template.yml -o out.yml

You can also use a cnfsane in a docker image.

docker run -it --rm -v ${PWD}:/app mneil/cfnsane template.yml -o out.yml
# or from github
docker run -it --rm -v ${PWD}:/app ghcr.io/mneil/cfnsane template.yml -o out.yml

See available commands by running cfnsane --help or simply cfnsane.

Library

You may wish to use Cfnsane to create your own sane defaults for AWS resources. Cfnsane uses the AWS CDK under the hook. You can write AWS CDK like normal and attach cfnsane to your stack or individual contructs to enforce sane defaults.

const cfnsane = require('cfnsane');
const cdk = require('@aws-cdk/core');
const s3 = require('@aws-cdk/aws-s3');

/**
 * Stack ingests a template from disk and creates
 * a CDK Stack
 */
class Stack extends cdk.Stack {
    constructor(scope, id, props = {}) {
        super(scope, id, props);
        new s3.Bucket(this, 'MyBucket', {bucketName: 'my-bucket'})
    }
}

const app = new cdk.App();
const stack = new Stack(app, 'Stack');

cfnsane.attach(stack);

Now use the CDK like normal. Running cdk synth from the example above will create a stack with a bucket and explicitly set block public access configuration for you.