Month: February 2022

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?

Good Morning from my Robotics Lab! This is Shadow_8472, and today I am working on a dice bot for a role play on Discord for a few friends. Let’s get started!

Seeking a Container

Many projects are like a tree in terms of having a general sense of progression up from the root and the fine details take most of the work to perfect. This week, my project was a rose bush. I have an end-goal in mind, but I want to run it from a container, a technology I still haven’t fully introduced myself to.

My plan started out simple: find a Discord dice bot already in a container and get it on the server. DockerHub, a sizable repository of OCI (Open Container Initiative) container images. (Most places call them Docker Containers due to its popularity over the past ten+ years. Searches for help should be worded accordingly.) I located about the only one that met all my simple criteria and made myself a bot account for it.

Discord bot accounts are more similar to human accounts than I gave them credit for. The only big differences are that bot accounts log in with a token instead of a username/password and the interface is different to accommodate a program instead of a human. Just as you only interface with your account to make posts, so too does a bot interface with its account to make posts. Give the login to someone or something else, and Discord shouldn’t care.

Long story short, the bot was set up to use an environment variable when using the image to make a container. Once I got it logged in, it ran into other problems I wasn’t prepared to diagnose.

Learning to Build Containers

With my only obvious option a bust, I set my sights on a Discord dice roller I’ve used in the past made by SkyJedi for the Star Wars tabletop RPG’s and a generic spinoff called Genesys. The game I’ll be running is GURPS, which focuses on using 6-sided dice. Plus it has an interesting turn counter system for combat I’d like to try using. The rest is fluff to me this time around, so long as I get it working.

A quick tell of an intense week is when I spend a whole day watching tutorials on the same subject over and over again until I find one at my level. This was one of those weeks. I remember there being one breakthrough video right at my beginner level that let me go back and follow the logic of more advanced tutorials that previously dazed me. During this intense study session, I puzzled together how to use Buildah at a beginner level, what a Dockerfile does, and went from muck to murk in my understanding of Javascript.

Buildah is a for making OCI containers Podman can later run and another tool I haven’t yet explored can edit. Like Podman, Buildah’s corner of their ecosystem aims to replace Docker commands one for one. It’s a win for people switching from Docker, and a win for newcomers like me who can look back at pertinent Docker documentation.

Docker –at least– takes a layered approach to making containers. Using a Dockerfile (one word, also its file name with no extension) lets you build start with a base image and build it up layer by layer, one command at a time. Parts can then be swapped out and the image rebuilt as needed.

The Star Wars dice bot is written in Javascript. If there’s one thing I learned about Javascript this week, it’s that there are several “frameworks” for both front-end development (used to make things look nice for users) and back-end development (used for internal logic). More specifically: I needed to look into NodeJS, a back-end framework. Node has a few different base images on DockerHub, so I worked with the full one with the intent to swap it out for smaller ones for a much smaller image.

Assembling My Own Containers

It took a very special set of circumstances during my self-study for containers to really click. First, I’ve been working through the Podman plugin for Cockpit. Individual images and containers are presented in an intuitive way. Each container has tabs for info, logs, and console access. The life cycle of a container is tied to executing a single command, but if that command is to start a shell, I can interact directly with the container like I would at any other command line. I could test commands from there, and if I got something right, I could add it to the Dockerfile for my next iteration.

I was actually able to find SkyJedi’s Discord server and contact him directly. He wasn’t familiar with containers enough to help me, but he did direct me to a much simpler bot of his I was rapidly able to package into a Node container – and later a Node:Alpine container.

The difference was login token. No matter what I tried, the full dice bot would not accept its login token. I was not able to figure this out, though I came quite close.

Side Project

I’m considering a new weekly segment where I work with my 3D printer a little bit each week. This week, I printed up a calibration cube using everything I’ve learned so far. It’s still far from perfect. I still need to tune in my Z-braces, as I can tell from some faint ringing I can more easily feel by running my thumbnail across it. I still need to calibrate my E-steps, a process I may need to repeat a few times as I come up with interesting, new ways to improve my printer.

Takeaway

After all that, I looked ahead at a the database I’d need to deal with once I get the bot logging in, and I’m almost certain now that my time will be better served making my own bot in Python. Of minor interest, I was able to learn the curl command better. Rocky Linux apparently doesn’t come with wget, the terminal program I usually use to download files. Curl –on the other hand– copies the contents of links to the stream. When directed to a file, it does the same job as Wget. A cool trick I pulled off involved manually following a redirect link.

Final Question

I feel like a rose bush gardener with nothing to show for his work but the tools he’s learned to use along the way. What projects have you farmed up a bunch of dead ends on?