許可プレフィックスリスト完全ガイド

AWSTemplateFormatVersion: '2010-09-09'
Description: DXGW - TGW Association with Allowed Prefixes

Resources:
  DxGwTgwAssociation:
    Type: AWS::DirectConnect::TransitGatewayAssociation
    Properties:
      DirectConnectGatewayId: !Ref DirectConnectGateway
      GatewayId: !Ref TransitGateway
      AllowedPrefixes:
        - Cidr: '10.0.0.0/16'
        - Cidr: '10.1.0.0/16'

  DirectConnectGateway:
    Type: AWS::DirectConnect::DirectConnectGateway
    Properties:
      DirectConnectGatewayName: my-dxgw
      AmazonSideAsn: 64512

Outputs:
  AssociationId:
    Value: !Ref DxGwTgwAssociation

# Direct Connect Gateway
resource "aws_dx_gateway" "main" {
  name            = "my-dxgw"
  amazon_side_asn = 64512
}

# TGW Association with Allowed Prefixes
resource "aws_dx_gateway_association" "tgw" {
  dx_gateway_id         = aws_dx_gateway.main.id
  associated_gateway_id = aws_ec2_transit_gateway.main.id

  allowed_prefixes = [
    "10.0.0.0/16",
    "10.1.0.0/16",
  ]
}

# 集約版（推奨）
resource "aws_dx_gateway_association" "tgw_aggregated" {
  dx_gateway_id         = aws_dx_gateway.main.id
  associated_gateway_id = aws_ec2_transit_gateway.main.id

  # /16 × 2 を /15 に集約
  allowed_prefixes = [
    "10.0.0.0/15",
  ]
}