cfn-show

#!/usr/bin/python
import simplejson as json
import sys

from argparse import ArgumentParser
from os import path

script_name = path.basename(__file__)

parser = ArgumentParser()
parser.add_argument('file_name',
                    metavar='FILE', help='CloudFormation json file')

parser.add_argument('sections', metavar='SECTIONS', default='Resources',
                    nargs='?', help='A csv list of sections to display in the output')

parser.add_argument('resource', metavar='RESOURCE', nargs='?',
                    help='A single resource to display')

parser.add_argument('-n', '--names', '--show-names', action="store_true",
                    help='Show the name of an individual resource')

parser.add_argument('-i', '--indent', metavar='INDENT', type=int,
                    default=4, help='Indent size of the json output')

args = parser.parse_args()


with open(args.file_name) as stack_json:
    try:
        stack = json.load(stack_json)
    except json.JSONDecodeError:
        sys.stderr.write("%s: %s is not valid json. Exiting\n" % (script_name, args.file_name))
        sys.exit(1)


# these meta keys do not contain resources so we drop them
unneeded_keys = ('AWSTemplateFormatVersion', 'Description')
[stack.pop(k, None) for k in unneeded_keys]

if args.sections == 'sections':
    for section in sorted(stack.keys()):
        print section
    sys.exit(0)


if args.sections:
    sections = args.sections.split(',')
    sections = [s.capitalize() for s in sections]

    # verify all the section names exist in the json
    for section in sections:
        if section not in stack.keys():
            sys.stderr.write("%s: section '%s' is not in the template\n" % (script_name, section))
            sys.exit(1)
else:
    sections = stack.keys()


# if we had a single argument then display all the entries for that section
if not args.resource:
    for section in sorted(sections):
        for resource in sorted(stack[section].keys()):
            resource_type = stack[section][resource].get("Type", section)

            print("%s\n%s\n" % (resource, resource_type))
    sys.exit(0)


# if we had two arguments then expand a single resource
if args.resource in stack[section].keys():
    if args.names:
        print '"%s" : ' % args.resource,

    print(json.dumps(stack[section].get(args.resource), stack, indent=args.indent * ' '))
else:
    sys.stderr.write("Resource [%s] was not found in the [%s] section\n" % (args.resource, section))
    sys.exit(1)