Parse Cloudformation string response from AWS SDK in Python

Question

The AWS SDK in Python has a function get_template to get a Cloudformation template.

The fact is the TemplateBody is a return as string and even without " . This makes the parsing pretty hard.

Do you have any suggestions on how to properly parse it and manipulate the data as dict in Python3.x?

I've tried with yaml.load , json.loads but w/o any luck.

on Github theere is an issue about this but no one seems to take care of it

Answer 1

Try ruamel.yaml package. This is my test code,

import boto3
import sys
from ruamel.yaml import YAML

session = boto3.session.Session(region_name='<region>')
client = session.client('cloudformation')

response = client.get_template(StackName='<stackname>')

yaml = YAML()
result = yaml.load(response['TemplateBody'])

yaml.dump(result, sys.stdout)

and the result is

AWSTemplateFormatVersion: '2010-09-09'
Description: >
  AWS CloudFormation template to create a new VPC
  or use an existing VPC for ECS deployment
  in Create Cluster Wizard. Requires exactly 1
  Instance Types for a Spot Request.
Parameters:
  EcsClusterName:
    Type: String
    Description: >
      Specifies the ECS Cluster Name with which the resources would be
      associated
    Default: default
  EcsAmiId:
    Type: String
    Description: Specifies the AMI ID for your container instances.
  EcsInstanceType:
    Type: CommaDelimitedList
    Description: >
      Specifies the EC2 instance type for your container instances.
      Defaults to m4.large
    Default: m4.large
    ConstraintDescription: must be a valid EC2 instance type.
...

The result in my code is not string and even not dict type but it is a dict-like object of ruamel.yaml package. You can parse the element from the result such as

result['AWSTemplateFormatVersion']

where it gives

2010-09-09