amazon-web-services,amazon-cloudformation , How do I create an Ec2 Instance with a Public IP automatically **without** declaring an Elastic IP in cloudformation?

How do I create an Ec2 Instance with a Public IP automatically **without** declaring an Elastic IP in cloudformation?


Tag: amazon-web-services,amazon-cloudformation

In AWS Cloudformation, is there any way to declare an EC2 instance in VPC with a Public IP without the need to declare an Elastic IP and attach to it?

In AWS::AutoScaling::LaunchConfiguration, you could add a property "AssociatePublicIpAddress" to say the instances will accept a Public IP automatically. I am looking for the equivalent for AWS::EC2::Instance

Below is my cloudformation snippet for creating an EC2 instance. I can't any doc that mentions how to add a public IP without having to declare an Elastic IP beforehand.

"MyEc2Instance": {
    "Type": "AWS::EC2::Instance",
    "Properties": {
        "IamInstanceProfile": {
            "Ref": "MyEc2InstanceProfile"
        "ImageId": {
            "Fn::FindInMap": [
                    "Ref": "Region"
        "InstanceType": {
            "Fn::FindInMap": [
                    "Ref": "Region"
        "KeyName": {
            "Ref": "DefaultKeyPair"
        "Monitoring": "true",
        "SecurityGroupIds": [
                "Ref": "MyEc2SecurityGroup"
        "SubnetId": {
            "Ref": "MyBoxSubnet"
        "Tags": [
                "Key": "Name",
                "Value": "MyBox"


Assuming you are starting your instance in a VPC public subnet (i.e. a subnet that has a routing table incl. a rule to send traffic to to the Internet Gateway), just define AutoAssignPublicIPAddress property in the NetworkInterfaces group of your EC2 resource:

            "NetworkInterfaces" : [{
                 "AssociatePublicIpAddress" : "True",
                 "DeleteOnTermination" : "True",
                 "SubnetId" : { "Ref" : "PublicSubnet" },
                 "DeviceIndex" : "0",
                 "GroupSet" : [ { "Ref" : "SecurityGroup" } ]

See documentation at

If you are starting your instance in EC2 Classic networking (non VPC), it will receive a public IP address automatically.


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