Perform the following to Ensure an AWS Managed Config Rule for EIPs attached to EC2 instances within VPC

1. Go to the AWS Config console at https://console.aws.amazon.com/config
2. Select Rules tab from the left side.
3. Search for a Config Rule that checks whether all EIP addresses allocated to a VPC are attached to EC2 instances or in-use ENIs
4. Give specific name and description and save it.

Using the Amazon CLI:

• Create locally a json file (similar with the below sample) with the configuration of
  the Config Rule, and save it as /tmp/ConfigRule.json:
  • “Description”: “Checks whether all EIP addresses allocated to a VPC are attached to EC2 instances or in-use ENIs.”, “ConfigRuleName”: “eip-attached”, “Source”: { “Owner”: “AWS”, “SourceIdentifier”: “EIP_ATTACHED” }, “Scope”: { “ComplianceResourceTypes”: [ “AWS::EC2::EIP” ] }
    
    
• Create a Config Rule using the configuration saved earlier:
  aws configservice put-config-rule –config-rule file:///tmp/ConfigRule.json

References:
1. http://docs.aws.amazon.com/config/latest/developerguide/WhatIsConfig.html
2. http://docs.aws.amazon.com/cli/latest/reference/configservice/describe-config-
rules.html
3. http://docs.aws.amazon.com/cli/latest/reference/configservice/put-config-
rule.html