Category: Python

This is sample code for using Selenium Remote Grid in headful mode with `browser_use`. The sample also includes specifying the browser window’s viewport size.

Pitfalls when passing `--headless` or `-profile` to Selenium Firefox, and the right way to use `selenium.webdriver.FirefoxOptions`.

Python 3.13 enabled VERIFY_X509_STRICT by default, triggering "SSL: CERTIFICATE_VERIFY_FAILED certificate verify failed: Basic Constraints of CA cert not marked critical" against self-signed CA certs. Workaround: disable VERIFY_X509_STRICT in SSLContext.

Expose the Selenium Chromium / ChromeDriver `--remote-debugging-port` (CDP port) outside the container for external clients to connect.

When looking at the assertEqual method in Django's unit tests, the first argument is named 'first' and the second argument is named 'second'. It appears that there is no difference in the usage of these variables.

pipenv install throws "AttributeError: module 'pkgutil' has no attribute 'ImpImporter'" on Python 3.12. Run `python3 -m ensurepip --upgrade` in both the global and virtualenv, or rebuild the pipenv environment.

A memo about purchasing a development board featuring the ESP-WROOM-32 module, which appears when searching for "ESP32" on AliExpress, and has "HW-394" written on the board.

Here is the solution for resolving Input/output errors or Error code -36 that may occur when trying to copy files to an RP2040 microcontroller board or Raspberry Pi Pico while developing on Mac OS Sonoma.

Fix `symbol not found in flat namespace '_mysql_affected_rows'` when importing MySQLdb in Python — rebuild mysqlclient against the right MySQL client library.

Fix `npm install fibers` (node-fibers) failing with `ValueError: invalid mode: 'rU'` — its `setup.py` uses a deprecated flag, so install with Python 3.10 or older.

Configure a macOS Service (Quick Action) that copies the absolute path of the file or folder open in Finder to the clipboard.

Flash CircuitPython onto an ESP32 dev board (HW-394 / WROOM-32) and drive I/O in Python — bootloader mode and REPL connection.

When connecting to an SSH server using Python libraries like Fabric or Paramiko, if the versions are outdated, you may encounter the error "Authentication (publickey) failed."

I wrote a script to download the version of chromedriver that matches the currently installed version of Chrome.

Build an OpenVPN server that routes all clients in a segment through the VPN — from CA cert issuance to distributing `client.ovpn`.

Debug and work around `multipart/form-data` boundary issues during file upload in macOS WebKit (WKWebView / Safari).

Fix `pipenv install` failing with `RuntimeError: location not created nor specified` — remove the venv with `pipenv --rm` and let pipenv recreate it.

Why switch a Django Docker image from Alpine + uWSGI to Debian + Daphne (ASGI), with example Dockerfile and Kubernetes manifest changes.

Packages required (`apk add ...`) to `pip install cryptography` in an Alpine Linux Docker image, and how to handle common build errors.

A script to open a website and log in to Google using Python Selenium

Fix `pipenv lock` failures on M1 (Apple Silicon) Macs — wheels for `grpcio` / `cryptography` may not exist on arm64, so use Rosetta or pin compatible versions.

When installing `google-crc32c` ≥1.1.3 on Alpine Linux fails to build, work around it by setting CFLAGS to enable SSE4.2 explicitly.

Format a USB stick as FAT32 + MBR on a Mac — explicit MBR via `diskutil eraseDisk` arguments.

Replace legacy log analyzers (Webalizer / Analog) with GoAccess for Apache / nginx access logs — sample configuration and example output.

Here's an introduction to a code snippet that waits for an element to disappear, using Pyppeteer, which is Python's version of Puppeteer. The same approach should work similarly in Puppeteer's JavaScript version.

Even though the Pipfile specifies ```plaintext [packages] ... Werkzeug = "<1.0.0" ``` running ```plaintext pipenv install --system --skip-lock --dev --deploy ``` installs version 1.0.1.

Fix screen redraw issues when Mac Quick Look or Finder content is displayed on a DisplayLink-connected screen.

If a Django project that has been working until now fails to start after a long time with the following error: ``` version_info, _mysql.version_info, _mysql.__file__ NameError: name '_mysql' is not defined ```

Pass a logged-in session cookie from Selenium WebDriver into `requests` to download files that require a browser-bound session.

When you download a CSV from Amazon, it might sometimes be a TSV with a BOM.

1. If the certificate is in DER format, convert it to PEM

Building from source is easy

I'm writing this down because I always get flustered.

Impersonate a different user during Django debugging by swapping `request.session['_auth_user_id']` to test session-bound logic.

How to return a Shift-JIS (CP932) CSV download response from Django on Python 3 — write to StringIO as Unicode first, then encode to cp932 in one shot.

Get the SSL certificate expiration period using timedelta

Parallelize CPU-bound Python work with `multiprocessing.Pool` / `ProcessPoolExecutor` — minimal patterns and common pitfalls.

I should have used multiprocessing.pool.Pool orz

This is a method to launch Selenium from Python on a headless Linux system.

Fix an `import requests` failure caused by a missing `_ssl` module in Python 3 on macOS — rebuild Python via pyenv so it links against the system OpenSSL.

Couldn't find the configuration item, so I'll use a monkey patch.

When running `pip install pillow`, you might encounter the following error:

When you start the program, a list of files is displayed in the editor. You can modify and save the list.

I wanted to write a logger-like class and wondered, "Which would be more readable, using a generator or a class?" So I wrote and compared both.

When I switched to MacOS Lion and was setting up my environment, I encountered the following error when running iPython:

I'm not very confident about the GTK part

# -*- coding: utf-8 -*-

# -*- coding: utf-8 -*-

```python