boto3 run api calls in multiple regions of multiple accounts

boto3_cross_account_actions.py

#!/usr/bin/env python3

import boto3
import botocore

partition = 'aws'
regions = ['us-east-1', 'us-west-2']
skip_master_acct = True

organizations = boto3.client('organizations')
sts = boto3.client('sts')


def process_acct(acct_id):
  creds = sts.assume_role(
    RoleArn=f"arn:{partition}:iam::{acct_id}:role/OrganizationAccountAccessRole",
    RoleSessionName="crossacctaction",
  )['Credentials']
  assumed_role_sts = boto3.client(
    'sts',
    aws_access_key_id=creds['AccessKeyId'],
    aws_secret_access_key=creds['SecretAccessKey'],
    aws_session_token=creds['SessionToken'],
  )
  print(assumed_role_sts.get_caller_identity()['Arn'])
  for region in regions:
    assumed_role_ec2 = boto3.client(
      'ec2',
      region_name=region,
      aws_access_key_id=creds['AccessKeyId'],
      aws_secret_access_key=creds['SecretAccessKey'],
      aws_session_token=creds['SessionToken'],
    )

    for pg in assumed_role_ec2.get_paginator('describe_instances').paginate():
      for r in pg['Reservations']:
        for i in r['Instances']:
          print(acct_id, region, i['InstanceId'])


master_acct_id = organizations.describe_organization()['Organization']['MasterAccountId']

for pg in organizations.get_paginator('list_accounts').paginate():
  for acct in pg['Accounts']:
    if skip_master_acct and acct['Id'] == master_acct_id:
      continue
    process_acct(acct['Id'])
    print()