Check which users are not in groups

iam.py

import boto3

iam = boto3.resource('iam')


def list_users() -> list:
    """
    List all users in an account
    :return: list of usernames
    """
    usernames = []
    client = boto3.client("iam")
    paginator = client.get_paginator('list_users')
    for response in paginator.paginate():
        for user in response["Users"]:
            usernames.append(user['UserName'])
    return usernames


def list_groups() -> list:
    """
    List all groups in an account
    :return: list of group names
    """
    group_names = []
    client = boto3.client("iam")
    paginator = client.get_paginator('list_groups')
    for response in paginator.paginate():
        for user in response["Groups"]:
            group_names.append(user['GroupName'])
    return group_names


all_usernames = list_users()
print(f"Total of {len(all_usernames)} users found")
all_groups = list_groups()
print(f"Total of {len(all_groups)} groups found")

# Find all users in all groups
usernames_in_group = []
for group in all_groups:
    iam_group = iam.Group('GroupA')
    user_iterator_A = iam_group.users.all()
    for user in user_iterator_A:
        usernames_in_group.append(user.user_name)

users_not_in_groups = set(all_usernames) ^ set(usernames_in_group)
print(f"Found {len(users_not_in_groups)} users not beloging to any groups")
print(users_not_in_groups)