cfn-natgateway

Purpose

AWS CloudFormation does not support AWS Managed nat. This is a Lambda-backed custom resource to add support for AWS Managed nat to CloudFormation.

This package on NPM
This package on GitHub

Implementation

This Lambda makes use of the Lambda-Backed CloudFormation Custom Resource flow module, cfn-lambda (GitHub / NPM).

Usage

"MyNatgateway": {
  "Type": "Custom::Natgateway",
  "DependsOn": "MyEIP",
  "Properties": {
    "ServiceToken": {
      "Fn::Join": [
        ":",
        [
          "arn",
          "aws",
          "lambda",
          {
            "Ref": "AWS::Region"
          },
          {
            "Ref": "AWS::AccountId"
          },
          "function",
          "cfn-natgateway-0-1-1"
        ]
      ]
    },
    "SubnetId": {
      "Ref": "PublicSubnet"
    },
    "AllocationId": {
      "Fn::GetAtt": [ "MyEIP", "AllocationId"]
    }
  }
},

"PrivateRouteTable": {
  "Type": "AWS::EC2::RouteTable",
  "DependsOn": "MyNatgateway2",
  "Properties": {
    "VpcId": {
      "Ref": "VPC"
    },
    "Tags": [{
      "Key": "Application",
      "Value": {
        "Ref": "AWS::StackId"
      }
    }, {
      "Key": "Network",
      "Value": "Private"
    }]
  }
},

"PrivateRoute": {
  "Type": "Custom::Natroute",
  "DependsOn": "MyNatgateway",
  "Properties": {
    "ServiceToken": {
      "Fn::Join": [
        ":",
        [
          "arn",
          "aws",
          "lambda",
          {
            "Ref": "AWS::Region"
          },
          {
            "Ref": "AWS::AccountId"
          },
          "function",
          "cfn-natroute-0-1-1"
        ]
      ]
    },
    "RouteTableId": {
      "Ref": "PrivateRouteTable"
    },
    "DestinationCidrBlock": "0.0.0.0/0",
    "NatGatewayId": {
      "Ref": "MyNatgateway"
    }
  }
},

Installation of the Resource Service Lambda

Using the Provided Instant Install Script

The way that takes 10 seconds...

# Have aws CLI installed + permissions for IAM and Lamdba
$ npm install cfn-lambda cfn-natgateway cfn-natroute
$ node -e "var r='us-east-1';var c=require('cfn-lambda');c.deploy('cfn-natgateway', r, [r], null);c.deploy('cfn-natroute', r, [r], null);"

You will have this resource installed in the us-east-1 region!

Using the AWS Console

... And the way more difficult way.

IMPORTANT: With this method, you must install this custom service Lambda in each AWS Region in which you want CloudFormation to be able to access the Natgateway custom resource!

1. Go to the AWS Lambda Console Create Function view:

• us-east-1 / N. Virginia
• us-west-2 / Oregon
• eu-west-1 / Ireland
• ap-northeast-1 / Tokyo

2. Zip this repository into /tmp/Natgateway.zip

   $ cd $REPO_ROOT && zip -r /tmp/Natgateway.zip;

3. Enter a name in the Name blank. I suggest: CfnLambdaResouce-Natgateway

4. Enter a Description (optional).

5. Toggle Code Entry Type to "Upload a .ZIP file"

6. Click "Upload", navigate to and select /tmp/Natgateway.zip

7. Set the Timeout under Advanced Settings to 10 sec

8. Click the Role dropdown then click "Basic Execution Role". This will pop out a new window.

9. Select IAM Role, then select option "Create a new IAM Role"

10. Name the role lambda_cfn_natgateway (or something descriptive)

11. Click "View Policy Document", click "Edit" on the right, then hit "OK"

12. Copy and paste the ./execution-policy.json document.

13. Hit "Allow". The window will close. Go back to the first window if you are not already there.

14. Click "Create Function". Finally, done! Now go to Usage. Next time, stick to the instant deploy script.

Miscellaneous

License

MIT