VPC Flow Logs Missing

What this rule checks

Detects VPCs without flow logs configured.

How to fix it

1. 1Create an AWS::EC2::FlowLog resource targeting the VPC
2. 2Send logs to CloudWatch Logs or S3

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';

// FLAGGED: VPC created with no flow logs attached.
new ec2.CfnVPC(this, 'Vpc', { cidrBlock: '10.0.0.0/16' });

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';

const vpc = new ec2.CfnVPC(this, 'Vpc', { cidrBlock: '10.0.0.0/16' });

// FIXED: a flow log now captures all traffic for the VPC.
new ec2.CfnFlowLog(this, 'FlowLog', {
  resourceType: 'VPC',
  resourceId: vpc.ref,
  trafficType: 'ALL',
  logDestinationType: 'cloud-watch-logs',
  logGroupName: '/vpc/flow-logs',
  deliverLogsPermissionArn: 'arn:aws:iam::123456789012:role/flow-logs-role',
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss vpc-flow-logs-missing and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "vpc-flow-logs-missing", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::vpc-flow-logs-missing',
  reason: 'Why this is intentional',
});

Use the rule ID vpc-flow-logs-missing shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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