AWS Config
Developer Guide

lambda-inside-vpc

Checks whether an AWS Lambda function is in an Amazon Virtual Private Cloud. The rule is NON_COMPLIANT if the Lambda function is not in a VPC.

Identifier: LAMBDA_INSIDE_VPC

Trigger type: Configuration changes

Parameters:

subnetId

(Optional) Comma-separated list of subnet IDs that Lambda functions must be associated with.

AWS CloudFormation template

To create AWS Config managed rules with AWS CloudFormation templates, see Creating AWS Config Managed Rules With AWS CloudFormation Templates.