CDK Pipelines Step - CDK Change Analyzer (C2A)

This package contains PerformChangeAnalysis, a custom approval step for use with a CDK Pipelines pipeline. This approval step will help you:

• Review the changes that a CDK deployment will introduce to your infrastructure in a visual interface.
• Write rules to automatically classify certain changes as "safe" or "unsafe", making sure you only need to review changes if there is something important to review.

C2A is currently in Developer Preview. Let us know how this tool is working for you.

Usage

Add the following to your package.json:

{
  "dependencies": {
    "@aws-c2a/cdk-pipelines-step": "0.5.0"
  }
}

Make sure the following packages are in there as well, with a CDK version of 1.115.0 or higher:

{
  "dependencies": {
    "@aws-cdk/aws-codebuild": "<VERSION>",
    "@aws-cdk/aws-codepipeline": "<VERSION>",
    "@aws-cdk/aws-codepipeline-actions": "<VERSION>",
    "@aws-cdk/aws-iam": "<VERSION>",
    "@aws-cdk/aws-lambda": "<VERSION>",
    "@aws-cdk/aws-s3": "<VERSION>",
    "@aws-cdk/aws-secretsmanager": "<VERSION>",
    "@aws-cdk/aws-sns": "<VERSION>",
    "@aws-cdk/core": "<VERSION>",
    "@aws-cdk/pipelines": "<VERSION>",
    "constructs": "^3.3.69"
  }
}

Insert PerformChangeAnalysis by adding it as a pre step when adding a Stage to a CDK pipeline:

import { PerformChangeAnalysis } from '@aws-c2a/cdk-pipelines-step';

const stage = new MyApplicationStage(this, 'MyApplication');
pipeline.addStage(stage, {
  pre: [
    new PerformChangeAnalysis('Check', { stage }),
  ],
});

Effect on your pipeline

By inserting the PerformChangeAnalysis step before any stage deployment, the CDK Change Analyzer (C2A) will be run to visualize the changes that would be introduced to your deployment by the upcoming deployment, and a a Manual Approval step is added to the pipeline to give you an opportunity to review and confirm the changes. Your pipeline stage will look like this:

┌───────────────────────────────────────────────────────────────┐
│                      MyApplicationStage                       │
│                                                               │
│                                                               │
│  ┌─────────┐     ┌─────────┐     ┌─────────┐     ┌─────────┐  │
│  │         │     │         │     │         │     │         │  │
│  │  Check  │────▶│ Confirm │────▶│ Prepare │────▶│ Deploy  │  │
│  │         │     │         │     │         │     │         │  │
│  └─────────┘     └─────────┘     └─────────┘     └─────────┘  │
│                                                               │
└───────────────────────────────────────────────────────────────┘

Rules and automatic approvals

Rules can be used to automatically classify changes in a deployment. They can be classified along 2 different axes:

• Risk: changes can be classified as high, low or unknown risk. This helps human reviewers concentrate effort on the most important types of changes when making a determination on whether or not to proceed with the deployment.
• Effect: changes can be automatically approved, or always rejected. In the former case, if all changes in a deployment are automatically classified as approved, the human review is skipped. Otherwise, if any of the changes in a deployment are rejected the deployment will fail and not proceed.

To automatically classify changes according to rules, write a JSON file in the rules language and pass it to the PerformChangeAnalysis step:

import { RuleSet, PerformChangeAnalysis } from '@aws-c2a/cdk-pipelines-step';

const stage = new MyApplicationStage(this, 'MyApplication');
pipeline.addStage(stage, {
  pre: [
    new PerformChangeAnalysis('Check', {
      stage,
      ruleSet: RuleSet.fromDisk(resolve(__dirname, 'rules.json')),
    }),
  ],
});

By default, the PerformChangeAnalysis will always run a suite of rules that checks for broadening of IAM permissions, equivalent to what the CDK CLI will check for during cdk deploy. To turn this off, pass broadeningPermissions: false:

const stage = new MyApplicationStage(this, 'MyApplication');
pipeline.addStage(stage, {
  pre: [
    new PerformChangeAnalysis('Check', {
      stage,
      broadeningPermissions: false,
    }),
  ],
});

Get notified of a pending review

To get notified when there is a change that needs your manual approval, create an SNS Topic, subscribe your own email address, and pass it in as as the notificationTopic property:

import * as sns from '@aws-cdk/aws-sns';
import * as subscriptions from '@aws-cdk/aws-sns-subscriptions';
import * as pipelines from '@aws-cdk/pipelines';

const topic = new sns.Topic(this, 'SecurityChangesTopic');
topic.addSubscription(new subscriptions.EmailSubscription('test@email.com'));

const stage = new MyApplicationStage(this, 'MyApplication');
pipeline.addStage(stage, {
  pre: [
    new PerformChangeAnalysis('Check', {
      stage,
      notificationTopic: topic,
    }),
  ],
});