Containerized Development Environment

Good Morning from my Robotics Lab! This is Shadow_8472, and today I am building my own dice bot for Discord using containers. Let’s get started!

Overview

In last week’s post, I learned how difficult a Discord dice roller is to find that is either already in a container or suitable to install into one. However, I did develop my skills along the way, and I believe I’m ready to make a bot of my own from scratch.

Development Environment

None of my machines had Python on them (except perhaps excluding the odd Raspberry Pi I have laying around), so the first order of business was to set up my own environment inside a container. There are a number of base images for running Python, but for development, I chose the latest official Python.

Podman pull python:latest

I went back and forth several times with the geometry of my bot project. I ended up stashing my work last week into a directory and making another to hold this round. When I was done, I had three files of consequence: Dockerfile, requirements.txt file, and a directory called home.

When I tell Buildah to make an image, it first goes to the Dockerfile:

FROM python:latest
COPY requirements.txt .
RUN python -m pip install -r requirements.txt

This takes the Python image, copies in requirements.txt, and references it to install any dependencies that don’t come with Python by default, namely as discord.py. As such, requirements.txt had a single line:

discord

Container base images leave out a lot of quality of life programs one might expect on a normal Linux install, like a text editor. That’s where the home directory comes in.

podman run -t -v /home/shadow8472/<bot project>/home:/root:Z -i dice_development:latest /bin/bash

This command has Podman use that image to make a container, mount that home directory into the container as /root (:Z is to tell SELinux it’s all good), and start a bash shell. From here, I can

podman attach <container name>
cd /root

and run the bot’s .py file. With the shared directory, I can edit it from the relative comfort of the host computer, ButtonMash, and go straight to running it inside the container. Best of all, the container will keep running with the bot if my connection to the host is broken, like if the network drops out or if I willingly close the terminal window. When I want to keep working, I can reattach the container.

Login token as environment variable: will my mental innovation of using the dockerfile to assemble it into a format Python understands work?

Development

I don’t have many comments about the actual development of the bot. It’s been a while since I actually programmed, and it’s been longer still since Python. I learned the basics of async programming a few years ago, and discord.py is building on that introduction, but I’m not setting out to master it just yet.

On my way to first stable “release,” I was coding up a loop meant to fill an array with die rolls. A bit of C++ grammar slipped in, and only after asking around did I identify it on my own and fix it. Another time, I coded an echo! function to practice passing command extensions into my code.

Most of my time went into constantly overhauling the internal logic. My early prototype was hardcoded to build its output string one die at a time, but I had to rework the back end to store the dice as they came in so I could sum them up and display that separately. All this was done while trying to keep it in a near-functional state.

But there are times a feature needs invasive re-working. I have some code in my comments that eliminates string manipulation from a function that should only be dealing with numbers. I’ve tried learning a popular version control system called Git in the past, but I can feel that I might actually stick with it this time. I’ve started reviewing commands, but I have yet to start using it as of writing.

Side Project

My week started off rough. I found my Derpy Chips workstation with a blank screen when I went to pull up last week’s post for some last minute proofreading. Initial diagnostics showed the screen blanks 0-30 seconds after making a picture from waking up. I got some help pouring over journalctrl and Xorg logs, but everything looked normal. The problem persisted through rebooting, pulling the GPU (graphics card), booting to an external drive, driving the monitor with my laptop, and even using a DVI cable instead of an HDMI. Final diagnostics turned up a dying backlight. I re-enlisted a personal museum piece –a vintage cathode ray tube model– to fill in until a suitable replacement can be procured.

3D Printing

Turns out that while I can play Minecraft just fine on integrated graphics, Slic3r pushes a few too many polygons for a smooth experience. I can’t run the old monitor off the graphics card because the card doesn’t have a VGA connector. Until I get a replacement monitor –or at the very least an adapter– I’ll be stuck with printing pre-made .stl objects or else installing Slic3r on another workstation.

What I did instead this week was make my own profile picture for the dice bot. I found a few dice I used to role play with and set them up in my photo booth. I even used a bead from printing the Z-braces to support a die in the back. I tweaked the picture a bit in GIMP to make it look more like the actual dice before uploading it for my friends’ enjoyment. It was not fun to fight the .jpg compression the entire way.

Takeaway

Programming is a completely different side of technology than systems management. It’s been a rewarding experience assembling my own environment to work in. It will need even more tweaking if/when I need to adapt it for use with an IDE, but those are for people who either already know everything that’s going or or those who don’t care to learn what’s going on at a basic level.

Final Question

Async functions are weird. I am after a small function to both log and send a response message. How do I pass an async call to another function? Am I even asking the right question?