def extract_boto_args_from_env(env_vars):
    """Return boto3 client args dict with environment creds."""
    boto_args = {}
    for i in ['aws_access_key_id', 'aws_secret_access_key',
              'aws_session_token']:
        if env_vars.get(i.upper()):
            boto_args[i] = env_vars[i.upper()]
    return boto_args