boto3 validates the given endpoint_url by is_valid_endpoint_url

boto3_is_valid_enpoint_url.py

# @ref: https://github.com/boto/botocore/blob/develop/botocore/utils.py#L897
import re
import sys
from botocore.compat import urlsplit

def is_valid_endpoint_url(endpoint_url):
    """Verify the endpoint_url is valid.
    :type endpoint_url: string
    :param endpoint_url: An endpoint_url.  Must have at least a scheme
        and a hostname.
    :return: True if the endpoint url is valid. False otherwise.
    """
    parts = urlsplit(endpoint_url)
    hostname = parts.hostname
    if hostname is None:
        return False
    if len(hostname) > 255:
        return False
    if hostname[-1] == ".":
        hostname = hostname[:-1]
    allowed = re.compile(
        r"^((?!-)[A-Z\d-]{1,63}(?<!-)\.)*((?!-)[A-Z\d-]{1,63}(?<!-))$",
        re.IGNORECASE)
    return allowed.match(hostname)

print(sys.argv[1])
print(is_valid_endpoint_url(sys.argv[1]))

# boto3 validates the given endpoint_url by is_valid_endpoint_url 
# s3_client = boto3.client("s3", endpoint_url="http://127.0.0.1:4566")
# s3_client.create_bucket(Bucket=bucket_name)

# Invalid: endpoint_url="http://s3_emulator:4566"