update-terraform-refs.py

#!/usr/bin/env python

"""
Once you've used `terraforming` to generate both HCL resource defintions and a
`terraform.tfstate` file to import your existing AWS resources into terraform,
your new resources will be littered with references to specific AWS resource
IDs rather than symbolic references to terraform-level resources.

This script will attempt to rewrite those IDs with symbolic references, so that
terrafrom can properly manage the resources and build a dependency graph
between them.

Example usage, from within a directory containing your `terraform.tfstate`
file:

    cat my-resource-defs.tf | update-terraform-refs.py > my-updated-defs.tf
"""

import json
import re
import sys


def make_id_map():
    state = json.load(open('terraform.tfstate'))
    id_map = {}
    for module in state['modules']:
        for resource_name, resource_def in module['resources'].iteritems():
            rid = resource_def['primary']['id']
            if rid != resource_name.split('.')[-1]:
                id_map[rid] = resource_name
    return id_map


def main():
    id_map = make_id_map()
    defs = sys.stdin.read()
    for rid, name in id_map.iteritems():
        pattern = r'"%s"' % re.escape(rid)
        replace = r'"${%s.id}"' % name
        defs = re.sub(pattern, replace, defs)
    print defs


if __name__ == '__main__':
    sys.exit(main())