Ephes Blog

Found a workaround for the fastdeploy / SQLAlchemy / asyncpg / Linux deadlock bug. I now instantiate a new SQLAlchemy engine on every request. That's probably not very efficient, since it would be better to use the engine's built-in ability to hold a connection pool, but having working code is a good start.

Progress on having a landing page where people can create podcasts/blogs:

• Finished Add remove domain / deployed fqdn #14
• Finished Switch between cast / wordpress #2 for deployments 🍾 - it was a complete surprise for me that this is even possible. But since I have now a working deployment system where all responsibilities are nicely separated, it's possible no not only to deploy Django, but anything including weird stuff like Wordpress without having to worry the rest of my system might suffer.
• Finished Fix pytest warnings + some cleanup stuff and coverage

Articles

• An SPA Alternative
• How Did REST Come To Mean The Opposite of REST?
• How To Test Django Models (With Examples)
• Building the blog while flying it Series' Articles

Videos

• Two Sigma Presents Pandas at a Crossroads the Past Present and Future with Jeff Reback

Twitter

• In Python, partials are an easy way to reuse function code. 🐍 🤩
• Don't move elements in a list while looping over it! You will get surprising (wrong!) results: 😳 🤨
• Since #Python 3.7, modules can define __getattr__ to provide dynamic attributes on modules. Why use two-argument arithmetic when you can do it with one!? 😎 🥳 😍

Software

• django-readers | A lightweight function-oriented toolkit for better organisation of business logic and efficient selection and projection of data in Django projects.
• django-sesame has a new tutorial | I'm searching for a solution to be able to log in users for a newly deployed site without having to store a password. This could be one.

Podcasts

• UKW100 Brexit: Kopf unter der Decke (Unsere kleine Welt) | Yup, brexit is still a trainwreck.

Out of Context Images

Fought with strange bugs last week, also some work and much outdoor stuff.

For example when using Jupyter Notebooks in a Django environment, the PYTHONPATH was always set to some old project and therefore imports from my current project didn't work. And it was simply not possible to get the PYTHONPATH right. I could not find the old projects name in any config or virtualenv. Weird. But then I had a closer look at the kernels using jupyter kernelspec list:
 

$ jupyter kernelspec list
Available kernels:
  django_extensions    /Users/jochen/Library/Jupyter/kernels/django_extensions
  python3              /Users/jochen/.virtualenvs/foo/share/jupyter/kernels/python3

$ jupyter kernelspec list
Available kernels:
  django_extensions    /Users/jochen/.virtualenvs/foo/share/jupyter/kernels/django_extensions
  python3              /Users/jochen/.virtualenvs/foo/share/jupyter/kernels/python3

• Merged the old work in progress on the "Deployed Services Configuration"-issue to be able to work on this database bug without conflicts getting out of hand 🫣

Out of Context Images

Getting Started

Lately, I was asked about how to get started with web development and Python in general. I pointed out some books and tutorials but then thought about what could improve the probability of success over just pointing to a lot of information. And the only thing I could think of was: Implement a small project with Django step by step. Create a GitHub repository for the project. I will have a look at your progress and keep adding issues. And of course provide help when you get stuck.

If you have a better idea on how to help people get started, please tell me. I'm very interested to hear about it 🤓.

And then someone (maybe my wife) told me that writing down all those steps as a series of blogposts could be also helpful for other people. So here we are 😏. We had to choose a platform to use for this project and despite being a happy macOS user by myself we agreed upon using Debian / Ubuntu for this project.

Python Setup

Installing Python

The first rule of Python is: Don't use your preinstalled system Python!

This is especially true for Debian-based distributions since they brake the Python standard library up into smaller packages, which breaks all sorts of things in weird ways. Even really basic stuff like creating a virtual environment won't work anymore.

And you don't want to replace your system Python with a working one, because it's used by the distribution itself for internal purposes, which probably depends on a lot of bugs they introduced, so: No easy Python installation for you!

For now, I recommend using pyenv to manage your Python installations until something better comes along. Install it by cloning the git repository like this.

And then prepare your shell for using pyenv by using the appropriate snippet for your preferred shell.

Before being able to install a real Python version using pyenv, you have to install some packages that allow you to compile Python without errors.

And now the installation of Python should finally be possible.

Create a New Virtual Environment

Despite now having the standard libraries venv module available, I prefer using virtualenv to create virtual environments, because it's faster and automatically installs the latest versions of pip, wheel and setuptools in the virtual environments it creates, which means one line less to type.

Now just create a directory for your new project and build a new virtual environment for it.

The venv argument tells virtualenv which directory it should use to install the virtual environment. Using venv for that is a popular choice and IDEs like VSCode or PyCharm will automatically find and use it. The --prompt argument is used to configure what the activated virtual environment will add to your shell prompt. Using "." just uses the name of the current directory.

Now the last step is to activate your Python environment, which depends on your shell. Use venv/bin/activate for bash/zsh or venv/bin/activate.fish for the fish shell.

Congratulations, you have now set up Python for your new project. The next step will be to bootstrap Django 😎.

Progress on having a landing page where people can create podcasts/blogs:

• Wrote some tests for cast_registry
• Fixed some deprecation warnings
• Enabled a custom admin url for production
• I wanted to add a "remove this blog"-feature to cast_registry to make it easier for me to test deployments. My time estimate for this feature would have been "just a few hours". But this story kept spawning sub-issues and getting bigger and bigger. The initial estimation would have been far off. What would be more valuable: Stick to the original estimate and promise myself to fx it later or fix it now and forget about my estimation? My lesson from situations like this is that estimates are pretty worthless. I just try to maximize the value of the thing I'm working on and don't do any estimations. Below are some of the sub-issues 😅.
  • Just store the last seen deployment in the session and compare it with a newly fetched one to determine new steps to show to the client
  • Move deployment metadata into its own model | I tried to be more verbose on my thought process here, let's see whether it helps

Progress on having a landing page where people can create podcasts:

• Made cast_registry use postgres instead of sqlite, mainly because it's easier to integrate into existing backup / monitoring.
• Automated deployment / removal for cast_registry
• Created a service for fastdeploy to be able to deploy / remove single cast hosting instances (a podcast or blog)
• Being able to deploy a podcast / blog via a cast_registry instance running on my staging environment 🥳