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AWS Amazon EC2 Transit Gateway

This page shows how to write Terraform and CloudFormation for Amazon EC2 Transit Gateway and write them securely.

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aws_ec2_transit_gateway (Terraform)

The Transit Gateway in Amazon EC2 can be configured in Terraform with the resource name aws_ec2_transit_gateway. The following sections describe 3 examples of how to use the resource and its parameters.

Example Usage from GitHub

transit_gateway.tf#L2
resource "aws_ec2_transit_gateway" "NW-TransitGtwy-USWest1" {
  amazon_side_asn                 = 64512
  description                     = "HSIS-TransitGtwy"
  auto_accept_shared_attachments  = "disable"
  default_route_table_association = "disable"
  default_route_table_propagation = "disable"
main.tf#L27
resource "aws_ec2_transit_gateway" "first" {
  provider = aws.first

  tags = {
    Name = "terraform-example"
  }
tgw.tf#L1
resource "aws_ec2_transit_gateway" "_" {
    auto_accept_shared_attachments = "enable"
}

resource "aws_ram_resource_association" "_" {
  resource_arn       = aws_ec2_transit_gateway._.arn

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Parameters

>> from Terraform Registry

Explanation in Terraform Registry

Manages an EC2 Transit Gateway.

>> from Terraform Registry

Tips: Best Practices for The Other AWS Amazon EC2 Resources

In addition to the aws_default_vpc, AWS Amazon EC2 has the other resources that should be configured for security reasons. Please check some examples of those resources and precautions.

risk-label

aws_default_vpc

Ensure to avoid using default VPC

It is better to define the own VPC and use it.

risk-label

aws_network_acl_rule

Ensure your network ACL rule blocks unwanted inbound traffic

It is better to block unwanted inbound traffic.

risk-label

aws_ebs_volume

Ensure to use a customer-managed key for EBS volume encryption

It is better to use a customer-managed key for EBS volume encryption. It can be gain more control over the encryption by using customer-managed keys (CMK).

risk-label

aws_instance

Ensure to avoid storing AWS access keys in user data

It is better to avoid storing AWS access keys in user data. `aws_iam_instance_profile` could be used instead.

risk-label

aws_security_group

Ensure your security group blocks unwanted inbound traffic

It is better to block unwanted inbound traffic.

Review your AWS Amazon EC2 settings

In addition to the above, there are other security points you should be aware of making sure that your .tf files are protected in Shisho Cloud.

AWS::EC2::TransitGateway (CloudFormation)

The TransitGateway in EC2 can be configured in CloudFormation with the resource name AWS::EC2::TransitGateway. The following sections describe 10 examples of how to use the resource and its parameters.

Example Usage from GitHub

tgw.yml#L3
    Type: AWS::EC2::TransitGateway
    Properties:
      AutoAcceptSharedAttachments: enable
      DefaultRouteTableAssociation: enable
      DefaultRouteTablePropagation: enable
Transit%20Gateway.yml#L2
    Type: "AWS::EC2::TransitGateway"
    Properties:
      AmazonSideAsn: 65000
      Description: "TGW Route Integration Test"
      AutoAcceptSharedAttachments: "disable"
      DefaultRouteTableAssociation: "enable"
dev-transit-gateway-usw2.cfn.yml#L17
    Type: AWS::EC2::TransitGateway
dev-transit-gateway-usw2.cfn.yml#L17
    Type: AWS::EC2::TransitGateway
transit-gateway.template.yml#L13
    Type: AWS::EC2::TransitGateway
    Properties:
      AutoAcceptSharedAttachments: enable   # Hoping this makes attaching VPCs easier

Outputs:
  TransitGatewayId:
tgw.json#L6
            "Type": "AWS::EC2::TransitGateway",
            "Properties": {
                "Description": "TGW for LZ",
                "AutoAcceptSharedAttachments": "enable",
                "DefaultRouteTableAssociation": "disable",
                "DefaultRouteTablePropagation": "disable",
aws-quickstart-scca-transit-gateway-stack.json#L4
        "Type": "AWS::EC2::TransitGateway",
        "Properties": {
          "DefaultRouteTableAssociation": "disable",
          "DefaultRouteTablePropagation": "disable",
          "Tags": [
            {
EC2TransitGatewaySpecification.json#L22
    "AWS::EC2::TransitGateway": {
      "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html",
      "Properties": {
        "DefaultRouteTablePropagation": {
          "Required": false,
          "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html#cfn-ec2-transitgateway-defaultroutetablepropagation",
EC2TransitGatewaySpecification.json#L22
    "AWS::EC2::TransitGateway": {
      "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html",
      "Properties": {
        "DefaultRouteTablePropagation": {
          "Required": false,
          "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html#cfn-ec2-transitgateway-defaultroutetablepropagation",
EC2TransitGatewaySpecification.json#L22
    "AWS::EC2::TransitGateway": {
      "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html",
      "Properties": {
        "DefaultRouteTablePropagation": {
          "Required": false,
          "Documentation": "http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-transitgateway.html#cfn-ec2-transitgateway-defaultroutetablepropagation",

Parameters

>> from AWS CloudFormation Documentation

Explanation in CloudFormation Registry

Specifies a transit gateway.

You can use a transit gateway to interconnect your virtual private clouds (VPC) and on-premises networks. After the transit gateway enters the available state, you can attach your VPCs and VPN connections to the transit gateway.

To attach your VPCs, use AWS::EC2::TransitGatewayAttachment.

To attach a VPN connection, use AWS::EC2::CustomerGateway to create a customer gateway and specify the ID of the customer gateway and the ID of the transit gateway in a call to AWS::EC2::VPNConnection.

When you create a transit gateway, we create a default transit gateway route table and use it as the default association route table and the default propagation route table. You can use AWS::EC2::TransitGatewayRouteTable to create additional transit gateway route tables. If you disable automatic route propagation, we do not create a default transit gateway route table. You can use AWS::EC2::TransitGatewayRouteTablePropagation to propagate routes from a resource attachment to a transit gateway route table. If you disable automatic associations, you can use AWS::EC2::TransitGatewayRouteTableAssociation to associate a resource attachment with a transit gateway route table.

>> from AWS CloudFormation Documentation

The Other Related AWS Amazon EC2 Resources

Frequently asked questions

What is AWS Amazon EC2 Transit Gateway?

AWS Amazon EC2 Transit Gateway is a resource for Amazon EC2 of Amazon Web Service. Settings can be wrote in Terraform and CloudFormation.

Where can I find the example code for the AWS Amazon EC2 Transit Gateway?

For Terraform, the lahiruperamune/terraform-aws-import, anmoltoppo/Terraform and foresighttech/terraform-vpc-module source code examples are useful. See the Terraform Example section for further details.

For CloudFormation, the Iman0510/Sandbox, j-crotty/CloudFormation and cue-sh/stax source code examples are useful. See the CloudFormation Example section for further details.

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