ntlm_cache.py

import boto3
import requests
import json
import datetime
from dateutil import parser
from requests_ntlm import HttpNtlmAuth

# AWS clients
s3 = boto3.client('s3')
ssm = boto3.client('ssm')
kms = boto3.client('kms')

# S3 and cache configuration
bucket_name = 'your-s3-bucket'
object_key = 'cache/response.json'
cache_ttl_seconds = 3600  # TTL for the cache in seconds, e.g., 1 hour

# Parameter Store names for encrypted credentials
username_parameter_name = '/path/to/username'
password_parameter_name = '/path/to/password'

# URL of the on-premises IIS server
url = 'http://your-on-prem-iis-server/resource'

def get_decrypted_parameter(name):
    # Retrieve the encrypted parameter from SSM
    encrypted_value = ssm.get_parameter(Name=name, WithDecryption=True)['Parameter']['Value']
    return encrypted_value

def cache_response_in_s3(response_data):
    response_data['cache_timestamp'] = datetime.datetime.utcnow().isoformat()
    s3.put_object(Bucket=bucket_name, Key=object_key, Body=json.dumps(response_data))

def is_cache_valid(last_modified_dt_str, cache_timestamp_str):
    current_time = datetime.datetime.utcnow()
    last_modified_dt = parser.parse(last_modified_dt_str)
    cache_timestamp = parser.parse(cache_timestamp_str)
    
    if last_modified_dt > cache_timestamp or (current_time - cache_timestamp).total_seconds() > cache_ttl_seconds:
        return False
    return True

def get_cached_response_from_s3():
    try:
        response = s3.get_object(Bucket=bucket_name, Key=object_key)
        cached_data = json.loads(response['Body'].read())
        
        if is_cache_valid(cached_data.get('last_attr_modified_dt'), cached_data.get('cache_timestamp')):
            return cached_data
        else:
            return None
    except s3.exceptions.NoSuchKey:
        return None

def fetch_and_cache_data(username, password):
    # Try to get cached response
    cached_response = get_cached_response_from_s3()
    if cached_response:
        return cached_response
    
    # If no valid cache, make a new request
    session = requests.Session()
    session.auth = HttpNtlmAuth(username, password)
    response = session.get(url)
    
    if response.ok:
        response_data = response.json()
        # Cache the new response
        cache_response_in_s3(response_data)
        return response_data
    else:
        response.raise_for_status()

# Main process
username = get_decrypted_parameter(username_parameter_name)
password = get_decrypted_parameter(password_parameter_name)

response_data = fetch_and_cache_data(username, password)
print(response_data)