boto3: How to get the IP addresses of CloudFormation stack instances?

Question

I need to discover the private IP address for every host in a AWS CloudFormation stack.

The CloudFormation API (see http://boto3.readthedocs.io/en/latest/reference/services/cloudformation.html ) doesn't seem to have any direct support for extracting nodes given a stack ID. Is it even possible?

Answer 1

Yes it is possible but not straightforward.

1. Get list of stacks in your account/profile
2. Loop through the list and create a list of stack names
3. Get the stack resources (describe_stack_resources) for each stack(name)
4. Locate the resource where resource['LogicalResourceId'] == 'Ec2Instance'
5. Get the inst_id from that resource
6. Once you have the inst_id, you can get its attributes including private_ip using boto3.resource('ec2')

I have coded this and use it regularly. AWS may throttle your CF calls, if it is called too often.