AWS Config Terraform module

Enables AWS Config and adds managed config rules with good defaults.

Supported AWS Config Rules

ACM

• acm-certificate-expiration-check: Ensure ACM Certificates in your account are marked for expiration within the specified number of days.

AMI

• approved-amis-by-tag: Checks whether running instances are using specified AMIs.

CloudTrail

• cloudtrail-enabled: Ensure CloudTrail is enabled.
• cloud-trail-encryption-enabled: Ensure CloudTrail is configured to use server side encryption (SSE) with AWS KMS or CMK encryption.
• cloud-trail-log-file-validation-enabled: Checks whether AWS CloudTrail creates a signed digest file with logs.
• multi-region-cloud-trail-enabled: Ensure that there is at least one multi-region AWS CloudTrail enabled.

CloudWatch Logs

• cloudwatch-log-group-encryption: Ensure that CloudWatch Logs are encrypted.

EC2

• ec2-encrypted-volumes: Evaluates whether EBS volumes that are in an attached state are encrypted.
• ec2-volume-inuse-check: Checks whether EBS volumes are attached to EC2 instances.
• ebs-snapshot-public-restorable-check: Checks whether Amazon Elastic Block Store snapshots are not publicly restorable.

VPC

• eip-attached: Checks whether all EIP addresses that are allocated to a VPC are attached to EC2 or in-use ENIs.
• instances-in-vpc: Ensure all EC2 instances run in a VPC.
• vpc-default-security-group-closed: Checks that the default security group of any Amazon Virtual Private Cloud (VPC) does not allow inbound or outbound traffic.

GuardDuty

• guardduty-enabled-centralized: Checks whether Amazon GuardDuty is enabled in your AWS account and region.

IAM

• iam-password-policy: Ensure the account password policy for IAM users meets the specified requirements.
• iam-user-no-policies-check: Ensure that none of your IAM users have policies attached; IAM users must inherit permissions from IAM groups or roles.
• iam-group-has-users-check: Checks whether IAM groups have at least one IAM user.
• root-account-mfa-enabled: Ensure root AWS account has MFA enabled.
• iam-root-access-key: Ensure root AWS account does not have Access Keys.

Tagging

• required-tags: Checks if resources are deployed with configured tags.

RDS

• rds-instance-public-access-check: Checks whether the Amazon Relational Database Service (RDS) instances are not publicly accessible.
• rds-snapshots-public-prohibited: Checks if Amazon Relational Database Service (Amazon RDS) snapshots are public.
• rds-storage-encrypted: Checks whether storage encryption is enabled for your RDS DB instances.

S3

• s3-bucket-public-write-prohibited: Checks that your S3 buckets do not allow public write access.
• s3-bucket-ssl-requests-only: Checks whether S3 buckets have policies that require requests to use Secure Socket Layer (SSL).

Terraform Versions

Terraform 0.13. Pin module version to ~> 4.x. Submit pull-requests to master branch.

Terraform 0.12. Pin module version to ~> 3.0. Submit pull-requests to terraform012 branch.

Terraform 0.11. Pin module version to ~> 1.5.1. Submit pull-requests to terraform011 branch.

Usage

Note: This module sets up AWS IAM Roles and Policies, which are globally namespaced. If you plan to have multiple instances of AWS Config, make sure they have unique values for config_name.

Note: If you use this module in multiple regions, be sure to disable duplicative checks and global resource types.

module "aws_config" {
  source = "trussworks/config/aws"

  config_name        = "my-aws-config"
  config_logs_bucket = "my-aws-logs"
}

Requirements

Name	Version
terraform	>= 0.12.7, < 0.14
aws	>= 2.70, < 4.0
template	>= 2.0

Providers

Name	Version
aws	>= 2.70, < 4.0
template	>= 2.0

Inputs

Name	Description	Type	Default	Required
acm_days_to_expiration	Specify the number of days before the rule flags the ACM Certificate as noncompliant.	number	14	no
aggregate_organization	Aggregate compliance data by organization	bool	false	no
ami_required_tag_key_value	Tag/s key and value which AMI has to have in order to be compliant: Example: key1:value1,key2:value2	string	""	no
check_acm_certificate_expiration_check	Enable acm-certificate-expiration-check rule	bool	true	no
check_approved_amis_by_tag	Enable approved-amis-by-tag rule	bool	false	no
check_cloud_trail_encryption	Enable cloud-trail-encryption-enabled rule	bool	false	no
check_cloud_trail_log_file_validation	Enable cloud-trail-log-file-validation-enabled rule	bool	false	no
check_cloudtrail_enabled	Enable cloudtrail-enabled rule	bool	true	no
check_cloudwatch_log_group_encrypted	Enable cloudwatch-log-group-encryption rule	bool	true	no
check_ebs_snapshot_public_restorable	Enable ebs-snapshot-public-restorable rule	bool	true	no
check_ec2_encrypted_volumes	Enable ec2-encrypted-volumes rule	bool	true	no
check_ec2_volume_inuse_check	Enable ec2-volume-inuse-check rule	bool	true	no
check_eip_attached	Enable eip-attached rule	bool	false	no
check_guard_duty	Enable guardduty-enabled-centralized rule	bool	false	no
check_iam_group_has_users_check	Enable iam-group-has-users-check rule	bool	true	no
check_iam_password_policy	Enable iam-password-policy rule	bool	true	no
check_iam_root_access_key	Enable iam-root-access-key rule	bool	true	no
check_iam_user_no_policies_check	Enable iam-user-no-policies-check rule	bool	true	no
check_instances_in_vpc	Enable instances-in-vpc rule	bool	true	no
check_multi_region_cloud_trail	Enable multi-region-cloud-trail-enabled rule	bool	false	no
check_rds_public_access	Enable rds-instance-public-access-check rule	bool	false	no
check_rds_snapshots_public_prohibited	Enable rds-snapshots-public-prohibited rule	bool	true	no
check_rds_storage_encrypted	Enable rds-storage-encrypted rule	bool	true	no
check_required_tags	Enable required-tags rule	bool	false	no
check_root_account_mfa_enabled	Enable root-account-mfa-enabled rule	bool	false	no
check_s3_bucket_public_write_prohibited	Enable s3-bucket-public-write-prohibited rule	bool	true	no
check_s3_bucket_ssl_requests_only	Enable s3-bucket-ssl-requests-only rule	bool	true	no
check_vpc_default_security_group_closed	Enable vpc-default-security-group-closed rule	bool	true	no
config_aggregator_name	The name of the aggregator.	string	"organization"	no
config_delivery_frequency	The frequency with which AWS Config delivers configuration snapshots.	string	"Six_Hours"	no
config_logs_bucket	The S3 bucket for AWS Config logs.	string	n/a	yes
config_logs_prefix	The S3 prefix for AWS Config logs.	string	"config"	no
config_max_execution_frequency	The maximum frequency with which AWS Config runs evaluations for a rule.	string	"TwentyFour_Hours"	no
config_name	The name of the AWS Config instance.	string	"aws-config"	no
config_sns_topic_arn	An SNS topic to stream configuration changes and notifications to.	string	null	no
include_global_resource_types	Specifies whether AWS Config includes all supported types of global resources with the resources that it records.	bool	true	no
password_max_age	Number of days before password expiration.	number	90	no
password_min_length	Password minimum length.	number	14	no
password_require_lowercase	Require at least one lowercase character in password.	bool	true	no
password_require_numbers	Require at least one number in password.	bool	true	no
password_require_symbols	Require at least one symbol in password.	bool	true	no
password_require_uppercase	Require at least one uppercase character in password.	bool	true	no
password_reuse_prevention	Number of passwords before allowing reuse.	number	24	no
required_tags	A map of required resource tags. Format is tagNKey, tagNValue, where N is int. Values are optional.	map(string)	{}	no
required_tags_resource_types	Resource types to check for tags.	list(string)	[]	no
tags	Tags to apply to AWS Config resources	map(string)	{}	no

Outputs

Name	Description
aws_config_role_arn	The ARN of the AWS config role.
aws_config_role_name	The name of the IAM role used by AWS config
required_tags_rule_arn	The ARN of the required-tags config rule.

Upgrade Paths

Upgrading from 2.3.0 to 2.4.x

Version 2.4.0 changed how AWS Config IAM polcies would be attached to IAM roles. When applying the upgrade, you will likely see a race condition resulting in the following error

Error: Provider produced inconsistent result after apply

A second terraform apply should resolve the issue.

Developer Setup

Install dependencies (macOS)

brew install pre-commit go terraform terraform-docs

Testing

Terratest is being used for automated testing with this module. Tests in the test folder can be run locally by running the following command:

make test

Or with aws-vault:

AWS_VAULT_KEYCHAIN_NAME=<NAME> aws-vault exec <PROFILE> -- make test