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How to Parse Apache Log Files in Python
Parse Apache common log format lines into structured dictionaries using Python's standard library.
import re
from pathlib import Path
def parse_apache_line(line):
pattern = r'^(\S+) (\S+) (\S+) \[([^\]]+)\] "(\S+) (\S+) (\S+)" (\d{3}) (\S+)'
match = re.match(pattern, line)
if not match:
return None
ip, ident, user, timestamp, method, path, protocol, status, size = match.groups()
return …Observer Pattern in Python: Notify Listeners
Implement the Observer design pattern in Python with a Subject class that manages listeners and notifies them with messages.
class Subject:
def __init__(self):
self._observers = []
def attach(self, observer):
self._observers.append(observer)
def detach(self, observer):
self._observers.remove(observer)
def notify(self, message):
for observer in self._observers:
observer.update(me…Create a Python Script That Detects Website Technology Stack Automatically
This script sends an HTTP request to a URL and inspects headers and HTML content to identify technologies like servers, frameworks, and JavaScript libraries.
import requests
from re import search
def detect_tech_stack(url):
tech_stack = []
try:
response = requests.get(url, timeout=5, headers={'User-Agent': 'Mozilla/5.0'})
headers = response.headers
html = response.text.lower() if response.text else ''
# Check server header
…How to Build a Mock Route53 DNS API in Python
Create a mock DNS API server in Python that simulates Route53 record lookups and updates using the standard library.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse, parse_qs
class DNSUpdateHandler(BaseHTTPRequestHandler):
records = {"example.com": "1.2.3.4"}
def do_GET(self):
domain = parse_qs(urlparse(self.path).query).get("domain", [""])[0]
if dom…How to Create a Mock Docker Registry Auth Token Server in Python
Build a mock Docker Registry token authentication server that issues signed JWT-like tokens for push and pull access using Python's standard library.
import base64
import hashlib
import hmac
import json
import time
from http.server import BaseHTTPRequestHandler, HTTPServer
class TokenAuthHandler(BaseHTTPRequestHandler):
"""Mock Docker Registry token authentication server."""
SECRET_KEY = b"mock-secret-key"
def generate_token(self, username: str, pas…How to Implement a Weighted DNS Resolver with Failover in Python
Simulates a weighted DNS load balancer that distributes traffic across IPs by weight and automatically fails over when a server is marked unhealthy.
import random
import time
class WeightedDNSResolver:
def __init__(self, records):
self.records = records # list of (ip, weight)
self.total_weight = sum(weight for _, weight in records)
self.failed_ips = set()
def resolve(self):
available = [(ip, weight) for ip, weight in self…How to Send an Email with smtplib and a Mock Server in Python
Send an email using smtplib and verify it with a local aiosmtpd mock SMTP server — perfect for testing without a real mail server.
import smtplib
from email.message import EmailMessage
import aiosmtpd.controller as controller
import threading
def handle_message(server, session, envelope):
print(f"Mock server received message:")
print(f"From: {envelope.mail_from}")
print(f"To: {envelope.rcpt_tos}")
print(f"Subject: {envelope.cont…How to Build a Branch Protection Audit Mock API in Python
A mock HTTP API that serves branch protection rules for repositories and audits them for compliance, built with Python's standard library.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse, parse_qs
REPOSITORIES = {
"alpha": {
"default_branch": "main",
"branches": ["main", "develop", "feature-x"],
"protection_rules": {
"main": {"required_reviews": 2, "dismiss_…Mock smtplib to Test Patch Email Series in Python
Simulate sending a numbered series of patch emails with smtplib and verify the calls using unittest.mock without a real mail server.
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from unittest.mock import patch, Mock
def send_patch_series(subject_prefix, patches, smtp_host="localhost", smtp_port=25):
"""Simulate sending a series of patch emails."""
for i, patch_content in enumerate(patch…How to Load Test a Local API with Locust in Python
Defines a Locust load test that simulates traffic to local endpoints, enabling manual load testing against a development server.
from locust import HttpUser, task, between
class WebsiteUser(HttpUser):
wait_time = between(1, 3)
@task
def home_page(self):
self.client.get("/")
@task(3)
def about_page(self):
self.client.get("/about")
if __name__ == "__main__":
print("Run with: locust -f this_file.py --h…Build a BFF (Backend for Frontend) Mock Aggregator in Python
A minimal HTTP server implementing the BFF pattern that aggregates user data and orders from two mock backends into a single JSON response.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse
class MockBackendA:
def get_user(self, user_id):
return {"id": user_id, "name": "Alice", "service": "backend-a"}
class MockBackendB:
def get_orders(self, user_id):
return [
{…How to Implement a Simple MVVM Binding Mock in Python
A minimal Python implementation of the MVVM pattern, mocking data binding so views auto-update when the view model changes.
class BindingMock:
def __init__(self, view_model):
self.view_model = view_model
self.subscribers = []
def bind(self, property_name, callback):
self.subscribers.append((property_name, callback))
def set(self, property_name, value):
setattr(self.view_model, property_name, va…Implement a Consistent Hash Ring in Python
Build a minimal consistent hash ring with virtual nodes to map keys to servers stably as nodes are added or removed.
import hashlib
import bisect
class ConsistentHashRing:
def __init__(self, nodes=None, replicas=3):
self.replicas = replicas
self.ring = {}
self.sorted_keys = []
if nodes:
for node in nodes:
self.add_node(node)
def _hash(self, key):
return i…Build a Bulk Array POST Mock Server in Python
Creates an HTTP mock server that accepts POST requests with a JSON array and returns incremental IDs for each item.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse
class MockHandler(BaseHTTPRequestHandler):
def do_POST(self):
if urlparse(self.path).path != "/bulk":
self.send_response(404)
self.end_headers()
return
cont…Build a Mock REST API with PUT and GET in Python
A minimal mock REST server implementing idempotent PUT for resource replacement and GET for retrieval, built with Python's http.server module.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
from urllib.parse import urlparse
mock_db = {}
class MockAPIHandler(BaseHTTPRequestHandler):
def do_PUT(self):
parsed = urlparse(self.path)
resource_id = parsed.path.strip("/").split("/")[-1]
content_length = int(self.…How to Build a Batch Operations Multi-Status 207 Mock Server in Python
Build a mock HTTP server that accepts a batch of operations and returns HTTP 207 Multi-Status with per-operation status codes in JSON.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
class BatchHandler(BaseHTTPRequestHandler):
def do_POST(self):
if self.path != "/batch":
self.send_response(404)
self.end_headers()
return
content_length = int(self.headers.get("Content-Leng…How to Build a Mock REST GET Endpoint Handler in Python
Create a lightweight mock REST GET server in Python using the standard library, with a dict-based route registry that maps paths to handler functions and returns JSON responses with proper HTTP status codes.
from http.server import BaseHTTPRequestHandler, HTTPServer
import json
# Mock API handler registry
def handle_users():
return {"status": "ok", "data": [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]}
def handle_products():
return {"status": "ok", "data": [{"id": 101, "name": "Laptop", "price": 999.99}…How to Build an Idempotency-Key POST Handler in Python
Python HTTP server mock that accepts POST requests and deduplicates them using an Idempotency-Key header, returning the same response for repeated calls.
import hashlib
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse
class MockAPI(BaseHTTPRequestHandler):
responses = {}
def do_POST(self):
length = int(self.headers.get("Content-Length", 0))
body = self.rfile.read(length).decode("utf-8")
…How to Implement Content Negotiation with JSON and XML in Python
Build an HTTP server that returns JSON or XML responses based on the client's Accept header, with a 406 response for unsupported formats.
import json
import xml.etree.ElementTree as ET
from http.server import BaseHTTPRequestHandler, HTTPServer
class RequestHandler(BaseHTTPRequestHandler):
def do_GET(self):
data = {"message": "Hello, world!"}
accept_header = self.headers.get("Accept", "")
if "application/json" in accept_hea…How to Mock X-RateLimit Headers in Python
This code creates a local HTTP server that mimics rate limit headers (X-RateLimit-Limit, Remaining, Reset, Update) and returns 429 responses when the limit is exceeded.
import time
import threading
from http.server import BaseHTTPRequestHandler, HTTPServer
class RateLimitHandler(BaseHTTPRequestHandler):
RATE_LIMIT = 5 # max requests allowed
WINDOW_SECONDS = 60 # per time window
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
…How to Mock a 202 Accepted Long-Running Operation in Python
Build a mock HTTP server that returns a 202 Accepted response immediately and simulates a long-running operation in the background with threading.
import time
import threading
from http.server import HTTPServer, BaseHTTPRequestHandler
class MockHandler(BaseHTTPRequestHandler):
def do_POST(self):
if self.path == "/long-running":
self.send_response(202)
self.send_header("Content-Type", "application/json")
self.end_h…How to Mock a Chunked Encoding Streaming Response in Python
Build a local mock HTTP server with Python's http.server that streams a chunked-encoded response with a 0.5s delay per chunk.
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
import time
class ChunkedHandler(BaseHTTPRequestHandler):
protocol_version = "HTTP/1.1"
def do_GET(self):
self.send_response(200)
self.send_header("Content-Type", "text/plain")
self.send_header("Transfer-Encoding", "c…How to Mock a Webhook Subscribe Callback URL in Python
Mock a webhook subscribe callback URL using Python's http.server to receive and parse POST requests sent by webhook providers.
import json
from http.server import BaseHTTPRequestHandler, HTTPServer
class WebhookHandler(BaseHTTPRequestHandler):
def do_POST(self):
content_length = int(self.headers.get('Content-Length', 0))
payload = json.loads(self.rfile.read(content_length)) if content_length else {}
print…How to mock Server-Sent Events (SSE) in Python
A minimal HTTP server that streams Server-Sent Events to clients, perfect for testing and development.
from http.server import HTTPServer, BaseHTTPRequestHandler
import threading
import time
MESSAGES = iter([
"data: Hello world\n\n",
"data: Second message\n\n",
"event: custom\n",
"data: Custom event payload\n\n",
"data: Final message\n\n"
])
class SSEHandler(BaseHTTPRequestHandler):
def do_GET…Browse by section
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