Call any AWS service directly using the credentials of AWS IoT device certificate

aws_iot_direct_call.py

'''
A snippet demonstrating how an AWS IoT device can make direct calls to every AWS
service using only the device certificate and private key.

For more info see the docs at https://docs.aws.amazon.com/iot/latest/developerguide/authorizing-direct-aws.html
to create the role and the role alias. To get the AWS IoT credential provider endpoint of your account you can use

    $ aws iot describe-endpoint --endpoint-type iot:CredentialProvider
    
Dependencies: requests and boto3

    $ pip install requests boto3

'''
import requests
import boto3

def get_session(endpoint, role_alias, cert, key, root_ca):
    ''' Get a boto3 session using the credentials of AWS IoT device certificate.
    
    Params:
      - endpoint: The AWS IoT credential provider endpoint of your account
      - role_alias: The name of the AWS IoT role alias
      - cert: The filename of your device certificate
      - key: The filename of your private key
      - root_ca: The filename of the root CA certificate
      
    Returns:
      - A configured boto3 session object that can be used to make direct calls
        to AWS services enabled by the assumed role.
    '''
    url = f'https://{endpoint}/role-aliases/{role_alias}/credentials'
    resp = requests.get(url, cert=(cert, key), verify=root_ca)
    credentials = resp.json()['credentials']
    session = boto3.session.Session(
        aws_access_key_id=credentials['accessKeyId'],
        aws_secret_access_key=credentials['secretAccessKey'],
        aws_session_token=credentials['sessionToken']
    )
    return session

Thank you for this!
For anyone else that comes across this- if you want to use ${credentials-iot:ThingName} in your iam role, you must add the "x-amzn-iot-thingname" header to the request