aws-shield

This component is responsible for enabling AWS Shield Advanced Protection for the following resources:

• Application Load Balancers (ALBs)
• CloudFront Distributions
• Elastic IPs (NAT Gateways, EC2 instances)
• Route53 Hosted Zones

About AWS Shield

AWS Shield is a managed DDoS (Distributed Denial of Service) protection service that safeguards applications running on AWS.

AWS Shield has two tiers:

Feature	Shield Standard	Shield Advanced
Cost	Free (included with AWS)	$3,000/month per organization
Protection	Layer 3/4 (network/transport)	Layer 3/4/7 (includes application layer)
Resources	All AWS resources	Specific protected resources
DRT Access	No	Yes (24/7 DDoS Response Team)
Cost Protection	No	Yes (credits for DDoS-related scaling)
Advanced Metrics	No	Yes (CloudWatch metrics)
WAF Integration	Basic	Advanced (custom rules during attacks)

This component configures AWS Shield Advanced protection for specific resources.

Prerequisites

This component requires that the account where it is being provisioned has been subscribed to AWS Shield Advanced.

Important: The Shield Advanced subscription is a manual step that must be completed before deploying this component:

# Subscribe via AWS CLI
aws shield create-subscription

# Or subscribe via AWS Console:
# AWS Shield → Getting started → Subscribe to Shield Advanced

This component assumes that resources it is configured to protect are not already protected by other components that have their xxx_aws_shield_protection_enabled variable set to true.

Usage

Stack Level: Global or Regional

AWS Shield Advanced protects both global and regional resources. Deploy this component to the appropriate stack level based on the resources you want to protect:

Resource Type	Stack Level	Example Stack
Route53 Hosted Zones	Global	plat-gbl-prod-shield
CloudFront Distributions	Global	plat-gbl-prod-shield
Application Load Balancers	Regional	plat-use1-prod-shield
Elastic IPs	Regional	plat-use1-prod-shield

Complete Example (All Resources)

The following snippet shows how to use all of this component's features in a stack configuration:

components:
  terraform:
    aws-shield:
      metadata:
        component: aws-shield
      settings:
        spacelift:
          workspace_enabled: true
      vars:
        enabled: true
        # Global resources
        route53_zone_names:
          - example.com
          - api.example.com
        cloudfront_distribution_ids:
          - E1ABCDEFG12345
          - E2BCDEFGH23456
        # Regional resources
        alb_protection_enabled: true
        alb_names:
          - k8s-common-2c5f23ff99
          - api-gateway-alb
        eips:
          - 3.214.128.240    # NAT Gateway AZ-a
          - 35.172.208.150   # NAT Gateway AZ-b
          - 35.171.70.50     # Bastion host

Global Stack Configuration

A typical global configuration includes Route53 hosted zones and CloudFront distributions. Global stacks typically don't have a VPC, so alb_names and eips should not be defined:

# stacks/catalog/aws-shield/global.yaml
components:
  terraform:
    aws-shield:
      metadata:
        component: aws-shield
      settings:
        spacelift:
          workspace_enabled: true
      vars:
        enabled: true
        route53_zone_names:
          - example.com
          - internal.example.com
        cloudfront_distribution_ids:
          - E1ABCDEFG12345

Regional Stack Configuration

Regional configurations protect ALBs and Elastic IPs. CloudFront distributions should not be defined in regional stacks (they are global resources):

# stacks/catalog/aws-shield/regional.yaml
components:
  terraform:
    aws-shield:
      metadata:
        component: aws-shield
      settings:
        spacelift:
          workspace_enabled: true
      vars:
        enabled: true
        # Protect ALBs by name
        alb_protection_enabled: true
        alb_names:
          - k8s-common-2c5f23ff99
        # Protect Elastic IPs (NAT Gateways, EC2 instances)
        eips:
          - 3.214.128.240
          - 35.172.208.150
        # Regional Route53 zones (if any)
        route53_zone_names:
          - us-east-1.example.com

Auto-Discovery from EKS ALB Controller

When alb_protection_enabled is true and alb_names is empty, the component automatically discovers ALB names from the eks/alb-controller-ingress-group component via remote state:

components:
  terraform:
    aws-shield:
      vars:
        enabled: true
        # Enable ALB protection with auto-discovery
        alb_protection_enabled: true
        # alb_names is intentionally empty - will be discovered from EKS ALB controller

Catalog Defaults Pattern

Create a catalog defaults file that can be imported and customized per environment:

# stacks/catalog/aws-shield/defaults.yaml
components:
  terraform:
    aws-shield:
      metadata:
        component: aws-shield
      vars:
        enabled: true
        alb_protection_enabled: false
        alb_names: []
        eips: []
        route53_zone_names: []
        cloudfront_distribution_ids: []

Then import and override in your stack:

# stacks/orgs/acme/platform/prod/us-east-1/shield.yaml
import:
  - catalog/aws-shield/defaults

components:
  terraform:
    aws-shield:
      vars:
        alb_protection_enabled: true
        alb_names:
          - prod-api-alb
        eips:
          - 52.1.2.3

Integration with Other Components

Stack configurations that rely on components with a xxx_aws_shield_protection_enabled variable should set that variable to true and leave the corresponding variable for this component empty, relying on that component's AWS Shield Advanced functionality instead. This simplifies inter-component dependencies and minimizes the need for maintaining the provisioning order during a cold-start.

Finding Resource Identifiers

Use the following AWS CLI commands to find resource identifiers:

# List ALB names
aws elbv2 describe-load-balancers --query 'LoadBalancers[*].LoadBalancerName' --output table

# List Elastic IPs
aws ec2 describe-addresses --query 'Addresses[*].[PublicIp,AllocationId,Tags[?Key==`Name`].Value|[0]]' --output table

# List Route53 hosted zones
aws route53 list-hosted-zones --query 'HostedZones[*].[Name,Id]' --output table

# List CloudFront distributions
aws cloudfront list-distributions --query 'DistributionList.Items[*].[Id,DomainName,Origins.Items[0].DomainName]' --output table

Verifying Protection Status

After deployment, verify resources are protected:

# List all protected resources
aws shield list-protections --query 'Protections[*].[Name,ResourceArn]' --output table

# Describe a specific protection
aws shield describe-protection --resource-arn <resource-arn>

# Check subscription status
aws shield describe-subscription

Variables

Required Variables

region (string) required

AWS Region

Optional Variables

alb_names (list(string)) optional

list of ALB names which will be protected with AWS Shield Advanced

Default value: [ ]

alb_protection_enabled (bool) optional

Enable ALB protection. By default, ALB names are read from the EKS cluster ALB control group

Default value: false

cloudfront_distribution_ids (list(string)) optional

list of CloudFront Distribution IDs which will be protected with AWS Shield Advanced

Default value: [ ]

eips (list(string)) optional

List of Elastic IPs which will be protected with AWS Shield Advanced

Default value: [ ]

route53_zone_names (list(string)) optional

List of Route53 Hosted Zone names which will be protected with AWS Shield Advanced

Default value: [ ]

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.

Required: No

Default value: { }

attributes (list(string)) optional

ID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.

Required: No

Default value: [ ]

context (any) optional

Single object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.

Required: No

Default value:

{
  "additional_tag_map": {},
  "attributes": [],
  "delimiter": null,
  "descriptor_formats": {},
  "enabled": true,
  "environment": null,
  "id_length_limit": null,
  "label_key_case": null,
  "label_order": [],
  "label_value_case": null,
  "labels_as_tags": [
    "unset"
  ],
  "name": null,
  "namespace": null,
  "regex_replace_chars": null,
  "stage": null,
  "tags": {},
  "tenant": null
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

Describe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
\{<br/> format = string<br/> labels = list(string)<br/> \}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

Limit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.

Required: No

Default value: null

label_key_case (string) optional

Controls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.

Required: No

Default value: null

label_order (list(string)) optional

The order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.

Required: No

Default value: null

label_value_case (string) optional

Controls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.

Required: No

Default value: null

labels_as_tags (set(string)) optional

Set of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
Notes:
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.

Required: No

Default value:

[
  "default"
]

name (string) optional

ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

Terraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

application_load_balancer_protections

AWS Shield Advanced Protections for ALBs

cloudfront_distribution_protections

AWS Shield Advanced Protections for CloudFront Distributions

elastic_ip_protections

AWS Shield Advanced Protections for Elastic IPs

route53_hosted_zone_protections

AWS Shield Advanced Protections for Route53 Hosted Zones

Dependencies

Requirements

• terraform, version: >= 1.0.0
• aws, version: >= 4.0

Providers

• aws, version: >= 4.0

Modules

Name	Version	Source	Description
alb	1.8.0	cloudposse/stack-config/yaml//modules/remote-state	n/a
iam_roles	latest	../account-map/modules/iam-roles	n/a
this	0.25.0	cloudposse/label/null	n/a

Resources

The following resources are used by this module:

• aws_shield_protection.alb_shield_protection (resource)
• aws_shield_protection.cloudfront_shield_protection (resource)
• aws_shield_protection.eip_shield_protection (resource)
• aws_shield_protection.route53_zone_protection (resource)

Data Sources

The following data sources are used by this module:

• aws_alb.alb (data source)
• aws_caller_identity.current (data source)
• aws_cloudfront_distribution.cloudfront_distribution (data source)
• aws_eip.eip (data source)
• aws_partition.current (data source)
• aws_route53_zone.route53_zone (data source)