Get Aurora IP and use it in UserData for another instance in AWS CloudFormation

Question

I have a CloudFormation script which creates 2 instances - an Aurora RDS server and an EC2 instance which will use it. I need to use the Aurora's IP address in my init script for the EC2 instance so I can seed the database.

So Aurora needs to be up and running before my init script on the EC2 executes. The other thing is I need the IP address.

"UserData"         : {
    "Fn::Base64" : {
        "Fn::Join" : [
            "",
            [
                "<script>\n",
                "seedtool.exe ", { "Ref" : "MyAuroraDbInstance::InternalIP" }, "\n",
                "</script>\n"
            ]
        ]
    }
},

So my question is, what do I put instead of MyAuroraDbInstance::InternalIP in the above script?

Answer 1

Use Fn::GetAtt on the DBInstance and request an attribute of Endpoint.Address. This will not give an IP, it will give a CNAME