Use python -m http.server in SSL

python -m http.server is a very convenient command line tool to start an ad-hoc static web server. This tool is very useful when you want to develop small web applications or serve static files. But it does not support SSL. A lot of modern web applications as well as browser features require a secured connection. So I want to wrap http.server in SSL and try making it simple to use. Continue reading

The contextvars and the chain of asyncio tasks in Python

In Python, the contextvars is somehow like thread local, but mostly for coroutines. But will the context itself be kept consistent in a chain of asyncio tasks? Let’s find out. contextvars Let’s have a rough review of the contextvars in Python. The contextvars module provides a way to maintain a context across a chain of function calls, natively supported with asyncio. For example import asyncio import contextvars var = contextvars.ContextVar('var', default={}) async def sub2(): print(f'in sub2, {var. Continue reading

Several tips for better working with Python in Excel

After enrolled for Python in Excel preview, now I can type =py( in any Excel cell to write some Python code. Python in Excel doesn’t have detailed documents, only Get Started tutorials, like link 1, link 2, or articles talking about topics like pandas, matplotlib, seaborn, etc., it may confuse you when you want to do some real work in an unfamiliar environment. The article notes several tips from my understanding of Python in Excel. Continue reading

Analyze robots.txt with Python Standard Library

If haven’t searched both “python” and “robots.txt” in the same input box, I would not ever know that Python Standard Library could parse robots.txt with urllib.robotparser. But the official document of urllib.robotparser doesn’t go into detail. With the document, you could check whether a url can be fetch with a robot with robot_parser_inst.can_fetch(user_agent, url) if you are building a crawler bot yourself. But if you want to do some statistics about robots. Continue reading

Process AWS Kinesis Firehose data with Python

Pipelining streamed data events directly into Amazon S3 via the AWS Kinesis Firehose service is convenient and efficient. And we could use Python with boto3 to consume the data directly from S3. This allows for seamless storage of your data, ensuring its integration and accessibility. Mostly, we are dealing with JSON-formatted event logs. But there is one tiny stone in the shoe for logs feeding from AWS Kinesis Firehose, there is no newline between consecutive log entries. Continue reading

Contextvars and Thread local

Here in the post, I will share some examples about the contextvars (new in Python 3.7) and thread local. Default Value In the module level, use ContextVar.set or directly setattr for a thread local variable, won’t successfully set a default value, the value set won’t take effect in another thread. To ensure a default value, for contextvars import contextvars context_var = contextvars.ContextVar("context_var", default=0) for thread local, a sub class of thread. Continue reading