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AWS CloudFormation
User Guide (API Version 2010-05-15)

Walkthrough: Peer with an Amazon VPC in Another AWS Account

You can peer with a virtual private cloud (VPC) in another AWS account by using AWS::EC2::VPCPeeringConnection. This creates a networking connection between two VPCs that enables you to route traffic between them so they can communicate as if they were within the same network. A VPC peering connection can help facilitate data access and data transfer.

To establish a VPC peering connection, you need to authorize two separate AWS accounts within a single AWS CloudFormation stack.

For more information about VPC peering and its limitations, see VPC Peering Overview in the Amazon VPC Peering Guide.

Prerequisites

  1. You need a peer VPC ID, a peer AWS account ID, and a cross-account access role for the peering connection.

    Note

    This walkthrough refers to two accounts: First is an account that allows cross-account peering (the accepter account). Second is an account that requests the peering connection (the requester account).

  2. To accept the VPC peering connection, the cross-account access role must be assumable by you. The resource behaves the same way as a VPC peering connection resource in the same account.

Step 1: Create a VPC and a Cross-Account Role

Create a VPC and a cross-account access role (example)

In this step, you'll create the VPC and role in the accepter account.

  1. In the AWS Management Console, choose AWS CloudFormation.

  2. Choose Create Stack.

  3. You have several options. To use AWS CloudFormation Designer to create a new, blank template, choose Design template.

    If you are creating the template in another text editor, choose Upload a template to Amazon S3 or Specify an Amazon S3 template URL, as appropriate.

  4. Use the following example template to create the VPC and the cross-account role allowing another account to achieve peering.

    Example JSON

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    { "AWSTemplateFormatVersion": "2010-09-09", "Description": "Create a VPC and an assumable role for cross account VPC peering.", "Parameters": { "PeerRequesterAccountId": { "Type": "String" } }, "Resources": { "vpc": { "Type": "AWS::EC2::VPC", "Properties": { "CidrBlock": "10.1.0.0/16", "EnableDnsSupport": false, "EnableDnsHostnames": false, "InstanceTenancy": "default" } }, "peerRole": { "Type": "AWS::IAM::Role", "Properties": { "AssumeRolePolicyDocument": { "Statement": [ { "Principal": { "AWS": { "Ref": "PeerRequesterAccountId" } }, "Action": [ "sts:AssumeRole" ], "Effect": "Allow" } ] }, "Path": "/", "Policies": [ { "PolicyName": "root", "PolicyDocument": { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": "ec2:AcceptVpcPeeringConnection", "Resource": "*" } ] } } ] } } }, "Outputs": { "VPCId": { "Value": { "Ref": "vpc" } }, "RoleARN": { "Value": { "Fn::GetAtt": [ "peerRole", "Arn" ] } } } }

    Example YAML

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    AWSTemplateFormatVersion: 2010-09-09 Description: Create a VPC and an assumable role for cross account VPC peering. Parameters: PeerRequesterAccountId: Type: String Resources: vpc: Type: 'AWS::EC2::VPC' Properties: CidrBlock: 10.1.0.0/16 EnableDnsSupport: false EnableDnsHostnames: false InstanceTenancy: default peerRole: Type: 'AWS::IAM::Role' Properties: AssumeRolePolicyDocument: Statement: - Principal: AWS: !Ref PeerRequesterAccountId Action: - 'sts:AssumeRole' Effect: Allow Path: / Policies: - PolicyName: root PolicyDocument: Version: 2012-10-17 Statement: - Effect: Allow Action: 'ec2:AcceptVpcPeeringConnection' Resource: '*' Outputs: VPCId: Value: !Ref vpc RoleARN: Value: !GetAtt - peerRole - Arn
  5. Choose Next.

  6. Give the stack a name (for example, VPC-owner), and then type the AWS account ID of the requester account in the PeerRequesterAccountId field.

  7. Accept the defaults, and then choose Next.

  8. Choose I acknowledge that AWS CloudFormation might create IAM resources, and then choose Create.

Step 2: Create a Template That Includes AWS::EC2::VPCPeeringConnection

Now that you've created the VPC and cross-account role, you can peer with the VPC using another AWS account (the requester account).

To create a template that includes the AWS::EC2::VPCPeeringConnection resource (example)

  1. Go back to the AWS CloudFormation console home page.

  2. Choose Create Stack.

  3. Choose Design template to use AWS CloudFormation Designer to create a new, blank template.

    If you are creating the template in another text editor, choose Upload a template to Amazon S3 or Specify an Amazon S3 template URL, as appropriate.

  4. Use the following example template to create a VPC and a VPC peering connection using the peer role you created in Step 1.

    Example JSON

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    { "AWSTemplateFormatVersion": "2010-09-09", "Description": "Create a VPC and a VPC Peering connection using the PeerRole to accept.", "Parameters": { "PeerVPCAccountId": { "Type": "String" }, "PeerVPCId": { "Type": "String" }, "PeerRoleArn": { "Type": "String" } }, "Resources": { "vpc": { "Type": "AWS::EC2::VPC", "Properties": { "CidrBlock": "10.2.0.0/16", "EnableDnsSupport": false, "EnableDnsHostnames": false, "InstanceTenancy": "default" } }, "vpcPeeringConnection": { "Type": "AWS::EC2::VPCPeeringConnection", "Properties": { "VpcId": { "Ref": "vpc" }, "PeerVpcId": { "Ref": "PeerVPCId" }, "PeerOwnerId": { "Ref": "PeerVPCAccountId" }, "PeerRoleArn": { "Ref": "PeerRoleArn" } } } }, "Outputs": { "VPCId": { "Value": { "Ref": "vpc" } }, "VPCPeeringConnectionId": { "Value": { "Ref": "vpcPeeringConnection" } } } }

    Example YAML

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    AWSTemplateFormatVersion: 2010-09-09 Description: Create a VPC and a VPC Peering connection using the PeerRole to accept. Parameters: PeerVPCAccountId: Type: String PeerVPCId: Type: String PeerRoleArn: Type: String Resources: vpc: Type: 'AWS::EC2::VPC' Properties: CidrBlock: 10.2.0.0/16 EnableDnsSupport: false EnableDnsHostnames: false InstanceTenancy: default vpcPeeringConnection: Type: 'AWS::EC2::VPCPeeringConnection' Properties: VpcId: !Ref vpc PeerVpcId: !Ref PeerVPCId PeerOwnerId: !Ref PeerVPCAccountId PeerRoleArn: !Ref PeerRoleArn Outputs: VPCId: Value: !Ref vpc VPCPeeringConnectionId: Value: !Ref vpcPeeringConnection
  5. Choose Next.

  6. Give the stack a name (for example, VPC-peering-connection).

  7. Accept the defaults, and then choose Next.

  8. Choose I acknowledge that AWS CloudFormation might create IAM resources, and then choose Create.

Creating a Template with a Highly Restrictive Policy

You might want to create a highly restrictive policy for peering your VPC with another AWS account.

The following example template shows how to change the VPC peer owner template (the accepter account created in Step 1 above) so that it is more restrictive.

Example JSON

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{ "AWSTemplateFormatVersion": "2010-09-09", "Description": "Create a VPC and an assumable role for cross account VPC peering.", "Parameters": { "PeerRequesterAccountId": { "Type": "String" } }, "Resources": { "peerRole": { "Properties": { "AssumeRolePolicyDocument": { "Statement": [ { "Action": [ "sts:AssumeRole" ], "Effect": "Allow", "Principal": { "AWS": { "Ref": "PeerRequesterAccountId" } } } ] }, "Path": "/", "Policies": [ { "PolicyDocument": { "Statement": [ { "Action": "ec2:acceptVpcPeeringConnection", "Effect": "Allow", "Resource": { "Fn::Sub": "arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc/${vpc}" } }, { "Action": "ec2:acceptVpcPeeringConnection", "Condition": { "StringEquals": { "ec2:AccepterVpc": { "Fn::Sub": "arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc/${vpc}" } } }, "Effect": "Allow", "Resource": { "Fn::Sub": "arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc-peering-connection/*" } } ], "Version": "2012-10-17" }, "PolicyName": "root" } ] }, "Type": "AWS::IAM::Role" }, "vpc": { "Properties": { "CidrBlock": "10.1.0.0/16", "EnableDnsHostnames": false, "EnableDnsSupport": false, "InstanceTenancy": "default" }, "Type": "AWS::EC2::VPC" } }, "Outputs": { "RoleARN": { "Value": { "Fn::GetAtt": [ "peerRole", "Arn" ] } }, "VPCId": { "Value": { "Ref": "vpc" } } } }

Example YAML

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AWSTemplateFormatVersion: 2010-09-09 Description: Create a VPC and an assumable role for cross account VPC peering. Parameters: PeerRequesterAccountId: Type: String Resources: peerRole: Properties: AssumeRolePolicyDocument: Statement: - Action: - 'sts:AssumeRole' Effect: Allow Principal: AWS: Ref: PeerRequesterAccountId Path: / Policies: - PolicyDocument: Statement: - Action: 'ec2:acceptVpcPeeringConnection' Effect: Allow Resource: 'Fn::Sub': 'arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc/${vpc}' - Action: 'ec2:acceptVpcPeeringConnection' Condition: StringEquals: 'ec2:AccepterVpc': 'Fn::Sub': 'arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc/${vpc}' Effect: Allow Resource: 'Fn::Sub': >- arn:aws:ec2:${AWS::Region}:${AWS::AccountId}:vpc-peering-connection/* Version: 2012-10-17 PolicyName: root Type: 'AWS::IAM::Role' vpc: Properties: CidrBlock: 10.1.0.0/16 EnableDnsHostnames: false EnableDnsSupport: false InstanceTenancy: default Type: 'AWS::EC2::VPC' Outputs: RoleARN: Value: 'Fn::GetAtt': - peerRole - Arn VPCId: Value: Ref: vpc

To access the VPC, you can use the same requester template as in Step 2 above.