/aws-cdk

Compliance and Drift Reference

Table of Contents

• Overview
• cdk-nag Setup and Rule Packs
  • Installation
  • Available Rule Packs
  • Applying Rule Packs
• Suppression Patterns
• Drift Detection
  • cdk drift vs cdk diff
  • Running Drift Detection
• Drift Resolution Strategies
• CI Integration
  • Strict Mode
  • cdk-nag in CI
  • Drift in CI
  • Security Scanning Layers
  • Strict Mode Rollout

Overview

CDK applications MUST be scanned for compliance violations before deployment and monitored for drift after deployment. cdk-nag provides compile-time policy enforcement. cdk drift detects runtime configuration changes made outside CDK.

cdk-nag Setup and Rule Packs

Installation

npm install cdk-nag

cdk-nag MUST be wired in before the first deploy to prevent non-compliant resources from ever reaching production.

Available Rule Packs

For SOX compliance, apply both NIST80053R5Checks and AwsSolutionsChecks together.

Applying Rule Packs

Rule packs are applied as CDK Aspects:

import { Aspects } from 'aws-cdk-lib';
import { AwsSolutionsChecks } from 'cdk-nag';

Aspects.of($APP).add(new AwsSolutionsChecks());

Multiple rule packs MAY be applied simultaneously:

Aspects.of($APP).add(new AwsSolutionsChecks());
Aspects.of($APP).add(new NIST80053R5Checks());

Suppression Patterns

When a finding is intentionally accepted, suppress it with NagSuppressions.addResourceSuppressions(). Every suppression MUST include a documented reason:

import { NagSuppressions } from 'cdk-nag';

NagSuppressions.addResourceSuppressions($CONSTRUCT, [
  {
    id: '$RULE_ID',
    reason: '$DOCUMENTED_JUSTIFICATION',
  },
]);

Suppressions MUST NOT be used to bypass findings without genuine justification.

Drift Detection

cdk drift vs cdk diff

• cdk diff compares the local CDK app against the last deployed template. It shows what a new deployment would change.
• cdk drift compares the deployed template against the actual live resource state. It shows out-of-band changes made outside CDK.

Running Drift Detection

Single stack:

cdk drift $STACK_NAME

All stacks:

cdk drift

Drift Resolution Strategies

When drift is detected, resolve it using one of these approaches (in order of preference):

1. Redeploy — Run cdk deploy $STACK_NAME to overwrite the drifted state with the CDK-defined state. This is the simplest resolution.

2. Adopt the change — If the out-of-band change is desired, update the CDK code to match the live state using Cfn<Resource>PropsMixin to adopt the drifted property values.

3. Fallback overrides — If Cfn<Resource>PropsMixin is not available for the resource type, use addPropertyOverride or node.defaultChild to set the property at the L1 level.

4. Handle deleted resources — If a resource was deleted outside CDK, remove it from the CDK code or re-import it.

Drift SHOULD be prevented proactively using SCPs (Service Control Policies) that restrict manual changes to CDK-managed resources.

CI Integration

Strict Mode

--strict MUST be passed on every cdk synth and cdk deploy in CI. Strict mode promotes warnings to build failures:

npx cdk synth --strict
npx cdk deploy $STACK_NAME --strict

Pair --strict with cdk-nag to catch both CDK warnings and compliance violations.

cdk-nag in CI

cdk-nag MUST be enforced in CI pipelines. Because rule packs are applied as Aspects, cdk synth will fail if any violations are found (when using --strict), blocking the deployment.

cdk-nag scans for:

• Over-permissive IAM policies
• Open security groups
• Unencrypted resources
• Missing logging

Drift in CI

Automate drift detection in CI with the --fail flag:

cdk drift --fail

This exits with a non-zero code when drift is detected, failing the pipeline.

Security Scanning Layers

1. Wire cdk-nag first as the primary compliance layer.
2. Add Checkov as a second scanning layer for additional coverage.

Strict Mode Rollout

To adopt --strict incrementally on an existing project:

1. Collect current warnings with cdk synth.
2. Triage each warning — determine if it is a real issue or acceptable.
3. Fix genuine issues; suppress accepted findings with NagSuppressions.
4. Enable --strict in CI once all warnings are resolved or suppressed.