AWS boto3 Assume Role (S3 example)

aws_assume.py

import boto3
from botocore.client import Config

sts_client = boto3.client('sts')

assumed_role_object = sts_client.assume_role(
    RoleArn="arn:aws:iam::111111111111:role/Administrator",
    RoleSessionName="testing-assume-role",
)
credentials = assumed_role_object['Credentials']

s3_resource = boto3.resource(
    's3',
    aws_access_key_id=credentials['AccessKeyId'],
    aws_secret_access_key=credentials['SecretAccessKey'],
    aws_session_token=credentials['SessionToken'],
)