cfcompare.py

#! /usr/bin/env python3


import boto3
import pprint
import json
import sys
from tempfile import mkstemp
import json_delta
from json_delta._util import read_bytestring
import argparse
import os


argparser = argparse.ArgumentParser(description='shows the difference between the template stored by cloudformation and the template stored on a s3 bucket, \n this script expect the AWS_* envvars to be present')
argparser.add_argument('-b', '--bucketname', nargs=1, default=None, required = True, help='Specify the bucket where the template is stored')
argparser.add_argument('-t', '--templatename', nargs=1, default=None, required = True, help='Template (file) name on the bucket')
argparser.add_argument('-s', '--stackname', nargs=1, default=None, help='Stack Name', required = True)
args = argparser.parse_args()



client = boto3.client('cloudformation')

response = client.get_template(
        StackName = args.stackname[0]
                )

# keys
# ResponseMetadata and TemplateBody
HTTPResponse = int(response['ResponseMetadata']['HTTPStatusCode'])

if HTTPResponse == 200:
    templateBody = response['TemplateBody']
else:
    print('http response != 200')
    sys.exit(1)



# get the template from S3
fd, tempfile = mkstemp()
s3 = boto3.resource('s3')
s3.meta.client.download_file(args.bucketname[0],args.templatename[0],tempfile)


s3template = json.load(open(tempfile))


flags = {'common_key_threshold': 0.0, 'array_align': 'udiff',
                 'compare_lengths': False}

right_text = str(json.dumps(s3template))
left_text = str(json.dumps(templateBody))
both_text = None
diff = json_delta.load_and_diff(left_text, right_text,
                                        verbose=False,
                                        **flags)

for line in json_delta.load_and_udiff(left_text, right_text,
                                                  both_text, diff):
	print(line.rstrip())


os.close(fd)
os.remove(tempfile)

sys.exit(0)